# CalcBright

> CalcBright (calcbright.com) offers free, accurate online calculators and converters. Every page explains its formula, shows a worked example, and gives instant results with no sign-up. Results are informational estimates, not financial, tax or medical advice.

AI assistants can run any calculator directly:
- MCP server (Streamable HTTP, no auth): https://calcbright.com/mcp
- JSON API: https://calcbright.com/api/calc/{tool}?param=value – spec: https://calcbright.com/openapi.json
- Full details of every tool: https://calcbright.com/llms-full.txt

## Finance
- [Mortgage Calculator](https://calcbright.com/mortgage-calculator): Free mortgage calculator: estimate your monthly house payment with property tax, insurance, PMI and HOA, plus a full amortization schedule and extra-payment savings.
- [Loan & EMI Calculator](https://calcbright.com/loan-calculator): Free loan and EMI calculator for personal, car, home and student loans. Get your monthly installment, total interest and a month-by-month repayment schedule.
- [Compound Interest Calculator](https://calcbright.com/compound-interest-calculator): Free compound interest calculator with monthly contributions. See how savings and investments grow year by year with daily, monthly or annual compounding.
- [Salary Converter](https://calcbright.com/salary-calculator): Convert hourly wage to annual salary and back. Free salary calculator for daily, weekly, bi-weekly, monthly and yearly pay, with optional take-home pay after tax.
- [401(k) Calculator](https://calcbright.com/401k-calculator): Free 401k calculator: project your balance at retirement from salary, contribution rate, employer match, raises and returns, with a year-by-year growth table.
- [APR Calculator](https://calcbright.com/apr-calculator): Free APR calculator: find the true annual percentage rate of a loan once origination and upfront fees are included, plus the monthly payment and total cost.
- [Auto Loan Calculator](https://calcbright.com/auto-loan-calculator): Free auto loan calculator: find your monthly car payment with sales tax, down payment and trade-in, plus total interest and a full amortization schedule.
- [Break-Even Calculator](https://calcbright.com/break-even-calculator): Free break-even calculator: enter fixed costs, price and variable cost per unit to find the break-even point in units and sales, plus the contribution margin.
- [Budget Calculator](https://calcbright.com/budget-calculator): Free budget calculator using the 50/30/20 rule: split your monthly take-home pay into needs, wants and savings, or set your own percentages for a custom plan.
- [CAGR Calculator](https://calcbright.com/cagr-calculator): Free CAGR calculator: find the compound annual growth rate between a beginning and ending value over any number of years, with total growth and a yearly path.
- [Car Lease Calculator](https://calcbright.com/car-lease-calculator): Free car lease calculator: estimate your monthly lease payment from price, down payment, residual, money factor or APR, term and sales tax, fully itemised.
- [Commission Calculator](https://calcbright.com/commission-calculator): Free commission calculator: work out sales commission from the sale amount and rate, add an optional base salary and compare total earnings at other rates.
- [Credit Card Payoff](https://calcbright.com/credit-card-payoff-calculator): Free credit card payoff calculator: see how many months it takes to clear your balance and the interest paid, or the payment needed to be debt-free by a date.
- [Debt-to-Income Calculator](https://calcbright.com/debt-to-income-calculator): Free debt to income ratio calculator: add up your monthly debt payments, get your DTI percentage and compare it with the 36% and 43% limits lenders use.
- [Discount Calculator](https://calcbright.com/discount-calculator): Free discount calculator: find the sale price and how much you save for any percent off, including stacked discounts like an extra 10% off a sale price.
- [Dividend Yield Calculator](https://calcbright.com/dividend-yield-calculator): Free dividend yield calculator: enter share price and dividend per share, paid yearly, quarterly or monthly, to get the yield and your annual income.
- [Down Payment Calculator](https://calcbright.com/down-payment-calculator): Free down payment calculator: see the down payment and loan amount for any home price, whether you will pay PMI, and compare 3%, 5%, 10% and 20% down.
- [FD Calculator](https://calcbright.com/fd-calculator): Free FD calculator: work out the maturity amount and interest on a bank fixed deposit with quarterly, monthly, half-yearly or yearly compounding.
- [GST Calculator](https://calcbright.com/gst-calculator): Free GST calculator for India: add or remove GST at 5%, 12%, 18%, 28% or 40% and see the CGST, SGST or IGST split and invoice total in rupees instantly.
- [Home Affordability](https://calcbright.com/home-affordability-calculator): Free home affordability calculator: see how much house you can afford from your income, debts and down payment using the 28/36 rule, with taxes and insurance.
- [Inflation Calculator](https://calcbright.com/inflation-calculator): Free inflation calculator: see what an amount will cost in the future, what past money is worth today, and how much purchasing power inflation erodes each year.
- [Markup Calculator](https://calcbright.com/markup-calculator): Free markup calculator: add a percentage markup to your cost to get the selling price, profit per unit and the gross margin it really gives you, at a glance.
- [Overtime Calculator](https://calcbright.com/overtime-calculator): Free overtime calculator: enter your hourly rate, regular and overtime hours to see regular pay, time-and-a-half or double-time pay and total gross pay.
- [Pay Raise Calculator](https://calcbright.com/pay-raise-calculator): Free pay raise calculator: enter your salary or hourly wage and a raise % or new pay to see the increase, % change and pay per month, week and hour.
- [Profit Margin Calculator](https://calcbright.com/profit-margin-calculator): Free profit margin calculator: enter cost and revenue to get gross profit, margin percentage and markup, plus the selling price needed for any target margin.
- [Refinance Calculator](https://calcbright.com/refinance-calculator): Free refinance calculator: compare your mortgage with a new rate and term to see the new payment, monthly savings, break-even month and lifetime interest.
- [Rent Affordability](https://calcbright.com/rent-affordability-calculator): Free rent affordability calculator: see how much rent you can afford from your salary using the 30% rule and the landlord 40x rule, adjusted for your debts.
- [Retirement Calculator](https://calcbright.com/retirement-calculator): Free retirement calculator: project your nest egg at retirement from savings and monthly contributions, then see how long withdrawals will last, year by year.
- [ROI Calculator](https://calcbright.com/roi-calculator): Free ROI calculator: work out your return on investment as a percentage, net profit or loss, and annualized ROI based on how long the money was invested.
- [Sales Tax Calculator](https://calcbright.com/sales-tax-calculator): Free sales tax calculator: add sales tax to any price or work backwards from a tax-inclusive total to the pre-tax price, using any state or local rate.
- [Savings Goal Calculator](https://calcbright.com/savings-goal-calculator): Free savings goal calculator: find out how much to save each month to reach a target amount by a deadline, counting current savings and interest earned.
- [Simple Interest Calculator](https://calcbright.com/simple-interest-calculator): Free simple interest calculator: work out the interest and total amount on any principal using I = P × r × t, with time entered in years, months or days.
- [SIP Calculator](https://calcbright.com/sip-calculator): Free SIP calculator: estimate the maturity value of a monthly mutual fund SIP, the amount invested and returns earned, with a year-by-year growth chart.
- [VAT Calculator](https://calcbright.com/vat-calculator): Free VAT calculator: add VAT to a net price or remove VAT from a gross amount at 20% or any rate, with UK, EU, UAE and Saudi standard rates compared.
- [Zakat Calculator](https://calcbright.com/zakat-calculator): Free zakat calculator: add up cash, gold, silver, investments and business assets, deduct debts due and check the gold or silver nisab for the 2.5% zakat due.

## Health & Fitness
- [BMI & Calorie Calculator](https://calcbright.com/bmi-calculator): Free BMI calculator for adults in kg/cm or lb/ft. Get your Body Mass Index, healthy weight range, BMR and daily calories (TDEE) to lose, maintain or gain weight.
- [BMR Calculator](https://calcbright.com/bmr-calculator): Free BMR calculator: find your basal metabolic rate with the Mifflin–St Jeor, revised Harris–Benedict and Katch–McArdle equations, plus calories by activity.
- [Body Fat Calculator](https://calcbright.com/body-fat-calculator): Free body fat calculator using the US Navy method: enter height, neck, waist and hip measurements to get your body fat %, ACE category, fat mass and lean mass.
- [Calorie Deficit Calculator](https://calcbright.com/calorie-deficit-calculator): Free calorie deficit calculator: get your maintenance calories, a safe daily calorie target for your weekly weight-loss goal and the weeks to your goal weight.
- [Calories Burned Calculator](https://calcbright.com/calories-burned-calculator): Free calories burned calculator: estimate calories burned walking, running, cycling, swimming, lifting and 20+ other activities from MET values and your weight.
- [Heart Rate Zone Calculator](https://calcbright.com/heart-rate-zone-calculator): Free heart rate zone calculator: find your max heart rate and 5 training zones by age with 220 − age or Tanaka, plus the Karvonen method using resting HR.
- [Ideal Weight Calculator](https://calcbright.com/ideal-weight-calculator): Free ideal weight calculator: find your ideal body weight for your height and sex using Robinson, Miller, Devine and Hamwi formulas plus a healthy BMI range.
- [Macro Calculator](https://calcbright.com/macro-calculator): Free macro calculator: get your daily calories and grams of protein, carbs and fat for weight loss, maintenance or muscle gain, with three diet-style splits.
- [One Rep Max Calculator](https://calcbright.com/one-rep-max-calculator): Free one rep max calculator: estimate your 1RM for bench press, squat or deadlift from any weight and reps using the Epley, Brzycki and Lombardi formulas.
- [Ovulation Calculator](https://calcbright.com/ovulation-calculator): Free ovulation calculator: estimate your ovulation day, fertile window and next period from your last period and cycle length, with dates for the next 4 cycles.
- [Pace Calculator](https://calcbright.com/pace-calculator): Free running pace calculator: get pace per km and per mile and speed from distance and time, or predict 5K, 10K, half marathon and marathon finish times.
- [Pregnancy Due Date Calculator](https://calcbright.com/pregnancy-due-date-calculator): Free pregnancy due date calculator: estimate your due date from your last period, conception or IVF transfer date and see how many weeks pregnant you are today.
- [Protein Calculator](https://calcbright.com/protein-calculator): Free protein calculator: find how many grams of protein you need a day for your weight and activity level, from the 0.8 g/kg RDA to 2.2 g/kg for muscle gain.
- [Sleep Calculator](https://calcbright.com/sleep-calculator): Free sleep calculator: find the best time to go to bed or wake up using 90-minute sleep cycles, so you wake between cycles feeling refreshed, not groggy.
- [Water Intake Calculator](https://calcbright.com/water-intake-calculator): Free water intake calculator: find how much water you should drink each day in litres, cups and ounces based on your body weight, daily exercise and climate.

## Math
- [Percentage Calculator](https://calcbright.com/percentage-calculator): Free percentage calculator: find X% of a number, what percent one number is of another, percentage change, increase and decrease – with step-by-step working.
- [Area Calculator](https://calcbright.com/area-calculator): Free area calculator for rectangles, squares, triangles, circles, trapezoids, parallelograms and ellipses. Enter sizes to get the area and formula.
- [Average Calculator](https://calcbright.com/average-calculator): Free average calculator: paste a list of numbers to get the mean, median, mode, range, count and sum instantly, with step-by-step working for each result.
- [Circle Calculator](https://calcbright.com/circle-calculator): Free circle calculator: enter the radius, diameter, circumference or area of a circle and instantly get the other three values, with formulas and working shown.
- [Fraction Calculator](https://calcbright.com/fraction-calculator): Free fraction calculator: add, subtract, multiply and divide fractions and mixed numbers. Get the simplified answer, mixed number, decimal and every step.
- [GPA Calculator](https://calcbright.com/gpa-calculator): Free GPA calculator: enter letter grades and credit hours for up to 8 courses to get your semester GPA on a 4.0 scale, plus your new cumulative GPA in seconds.
- [Final Grade Calculator](https://calcbright.com/grade-calculator): Free final grade calculator: enter your current grade, the final exam weight and the grade you want to see exactly what score you need on the final exam.
- [LCM & GCD Calculator](https://calcbright.com/lcm-gcd-calculator): Free LCM and GCD calculator: find the least common multiple and greatest common divisor (GCF or HCF) of up to 20 numbers, with prime factorizations and steps.
- [Logarithm Calculator](https://calcbright.com/logarithm-calculator): Free logarithm calculator: find log base 10, natural log (ln), log base 2 or a log with any custom base, with the change-of-base formula worked step by step.
- [Percent Error Calculator](https://calcbright.com/percent-error-calculator): Free percent error calculator: compare an experimental (measured) value with the theoretical (true) value to get percent, absolute and relative error.
- [Prime Number Checker](https://calcbright.com/prime-number-checker): Free prime number checker: test if any number up to one trillion is prime, see its smallest factor and prime factorization, and get the next and previous prime.
- [Pythagorean Theorem Calc](https://calcbright.com/pythagorean-theorem-calculator): Free Pythagorean theorem calculator: find the hypotenuse or a missing leg of a right triangle from a² + b² = c², plus area, perimeter, angles and every step.
- [Quadratic Equation Solver](https://calcbright.com/quadratic-equation-solver): Free quadratic equation solver: enter a, b and c to find the discriminant, real or complex roots and the vertex of ax² + bx + c = 0, with step-by-step working.
- [Random Number Generator](https://calcbright.com/random-number-generator): Free random number generator: pick one or many random numbers in any range, whole or decimal, with or without duplicates. Numbers are generated in your browser.
- [Ratio Calculator](https://calcbright.com/ratio-calculator): Free ratio calculator: solve A:B = C:D for any missing value, simplify ratios to lowest terms, and see the cross-multiplication steps. Ideal for recipes.
- [Square Root Calculator](https://calcbright.com/square-root-calculator): Free square root calculator: find the square root, cube root or any nth root of a number, simplify radicals like √72 = 6√2, and check the answer step by step.
- [Standard Deviation Calculator](https://calcbright.com/standard-deviation-calculator): Free standard deviation calculator: enter a data set to get the sample or population standard deviation, variance and mean, with a full step-by-step table.
- [Volume Calculator](https://calcbright.com/volume-calculator): Free volume calculator for cubes, boxes, cylinders, spheres, cones and pyramids. Enter dimensions to get the volume with its formula, plus litres and gallons.

## Converters
- [Unit Converter](https://calcbright.com/unit-converter): Free unit converter for length, weight, temperature, volume, area, speed, time, data, energy and pressure. Metric ↔ imperial with exact formulas and tables.
- [Currency Converter](https://calcbright.com/currency-converter): Free currency converter with exchange rates updated every few hours. Convert USD, EUR, GBP, INR, PKR, AED and 30+ currencies with quick conversion tables.
- [Case Converter](https://calcbright.com/case-converter): Free case converter: change text to UPPER CASE, lower case, Title Case, Sentence case, camelCase, snake_case or kebab-case instantly. Nothing is uploaded.
- [Cooking Converter](https://calcbright.com/cooking-converter): Free cooking converter: turn cups, tablespoons and teaspoons into grams or ounces for flour, sugar, butter, milk, oats, honey and more, with ingredient charts.
- [Fuel Economy Converter](https://calcbright.com/fuel-economy-converter): Free fuel economy converter: convert between US mpg, UK mpg, liters per 100 km and km per liter in one step, with a handy mpg to L/100 km comparison chart.
- [Height Converter](https://calcbright.com/height-converter): Free height converter: change centimeters to feet and inches or feet and inches to cm instantly, with a handy height chart from 150 cm to 200 cm.
- [Number Base Converter](https://calcbright.com/number-base-converter): Free number base converter: convert between binary, octal, decimal, hexadecimal and any base from 2 to 36, with very large numbers and step-by-step working.
- [Number to Words Converter](https://calcbright.com/number-to-words-converter): Free number to words converter: spell out any number up to 999 trillion in English, in check-writing format, or in the Indian lakh and crore system instantly.
- [Roman Numeral Converter](https://calcbright.com/roman-numeral-converter): Free Roman numeral converter: change any number from 1 to 3999 into Roman numerals or read a numeral back as a number, with a step-by-step breakdown.
- [Shoe Size Converter](https://calcbright.com/shoe-size-converter): Free shoe size converter: convert between US men's, US women's, UK, EU and Japanese cm sizes with a clear adult size chart, so online shoes fit the first time.

## Date & Time
- [Age Calculator](https://calcbright.com/age-calculator): Free age calculator: find your exact age in years, months, weeks and days from your date of birth, the day you were born and the countdown to your next birthday.
- [Time Zone Converter](https://calcbright.com/time-zone-converter): Free time zone converter: convert a date and time between any two cities, with daylight saving time handled automatically, plus a live world clock.
- [Business Days Calculator](https://calcbright.com/business-days-calculator): Free business days calculator: count working days (Monday–Friday) and weekend days between two dates, or add business days to a date to find a deadline.
- [Countdown Calculator](https://calcbright.com/countdown-calculator): Free countdown calculator: see how many days, weeks and months are left until Christmas, New Year or any date you choose – or how many days have passed since.
- [Date Calculator](https://calcbright.com/date-calculator): Free date calculator: add or subtract days, weeks, months and years from any date to find the resulting date and weekday, with leap years handled.
- [Date Difference Calculator](https://calcbright.com/date-difference-calculator): Free date difference calculator: count the days between two dates, plus weeks, months and years, business days and weekends, optionally including the end date.
- [Day of the Week Calculator](https://calcbright.com/day-of-week-calculator): Free day of the week calculator: find the weekday any date falls on, past or future, with step-by-step Zeller’s congruence working and the Doomsday rule.
- [Hours Calculator](https://calcbright.com/hours-calculator): Free hours calculator and time card: enter start, end and break times for each day of the week to total work hours, decimal hours and pay at your hourly rate.
- [Time Duration Calculator](https://calcbright.com/time-duration-calculator): Free time duration calculator: find the hours and minutes between two clock times, even across midnight, with the result in decimal hours and total minutes.
- [Time to Decimal Converter](https://calcbright.com/time-to-decimal-converter): Free time to decimal converter: change hours, minutes and seconds into decimal hours for timesheets and payroll, or turn decimal hours back into h:mm:ss format.
- [Unix Timestamp Converter](https://calcbright.com/unix-timestamp-converter): Free Unix timestamp converter: turn epoch seconds or milliseconds into a readable UTC date and ISO 8601 time, or convert any date and time to a Unix timestamp.
- [Week Number Calculator](https://calcbright.com/week-number-calculator): Free week number calculator: find the ISO 8601 week number of any date, the Monday and Sunday of that week, the day of the year and the days left in the year.

## Everyday
- [Concrete Calculator](https://calcbright.com/concrete-calculator): Free concrete calculator for slabs, footings and round columns: get the volume in cubic yards and cubic meters plus how many 40, 60, 80 lb or 25 kg bags to buy.
- [Electricity Cost Calculator](https://calcbright.com/electricity-cost-calculator): Free electricity cost calculator: find how many kWh an appliance uses and what it costs to run per day, month and year from its wattage, hours and your rate.
- [Flooring Calculator](https://calcbright.com/flooring-calculator): Free flooring calculator: work out room area, add a waste allowance, and find how many boxes of laminate, vinyl, tile or hardwood to buy and what it will cost.
- [Fuel Cost Calculator](https://calcbright.com/fuel-cost-calculator): Free fuel cost calculator: estimate the gas cost of any one-way or round trip from distance, mpg or L/100 km and fuel price, and split it between passengers.
- [Paint Calculator](https://calcbright.com/paint-calculator): Free paint calculator: enter your room size, doors, windows and coats to find the paintable wall area and how many gallons or liters to buy, rounded up.
- [Password Generator](https://calcbright.com/password-generator): Free strong password generator: create secure passwords of 8–64 characters with letters, numbers and symbols, plus entropy and strength. Made in your browser.
- [Speed Distance Time](https://calcbright.com/speed-distance-time-calculator): Free speed, distance and time calculator: solve for any one from the other two in km, miles, km/h or mph, with the formula and step-by-step working shown.
- [Square Footage Calculator](https://calcbright.com/square-footage-calculator): Free square footage calculator for rectangles, L-shaped rooms, circles and triangles. Get the area in sq ft, m², square yards and acres, plus the total cost.
- [Tip Calculator](https://calcbright.com/tip-calculator): Free tip calculator: work out the tip and total for any bill, split it between friends, and compare 10%, 15%, 18%, 20% and 25% tips instantly.
- [Word Counter](https://calcbright.com/word-counter): Free word counter: count words, characters with and without spaces, sentences and paragraphs, plus reading time, speaking time and your top keywords.

## Popular unit conversions
- [Centimeters to Inches](https://calcbright.com/unit-converter/cm-to-inches)
- [Inches to Centimeters](https://calcbright.com/unit-converter/inches-to-cm)
- [Feet to Meters](https://calcbright.com/unit-converter/feet-to-meters)
- [Meters to Feet](https://calcbright.com/unit-converter/meters-to-feet)
- [Kilometers to Miles](https://calcbright.com/unit-converter/km-to-miles)
- [Miles to Kilometers](https://calcbright.com/unit-converter/miles-to-km)
- [Kilograms to Pounds](https://calcbright.com/unit-converter/kg-to-pounds)
- [Pounds to Kilograms](https://calcbright.com/unit-converter/pounds-to-kg)
- [Celsius to Fahrenheit](https://calcbright.com/unit-converter/celsius-to-fahrenheit)
- [Fahrenheit to Celsius](https://calcbright.com/unit-converter/fahrenheit-to-celsius)
- [Milliliters to US cups](https://calcbright.com/unit-converter/ml-to-cups)
- [US cups to Milliliters](https://calcbright.com/unit-converter/cups-to-ml)
- [Liters to US gallons](https://calcbright.com/unit-converter/liters-to-gallons)
- [US gallons to Liters](https://calcbright.com/unit-converter/gallons-to-liters)
- [Grams to Ounces](https://calcbright.com/unit-converter/grams-to-ounces)
- [Ounces to Grams](https://calcbright.com/unit-converter/ounces-to-grams)
- [Square feet to Square meters](https://calcbright.com/unit-converter/square-feet-to-square-meters)
- [Acres to Hectares](https://calcbright.com/unit-converter/acres-to-hectares)
- [Kilometers per hour to Miles per hour](https://calcbright.com/unit-converter/kmh-to-mph)
- [Miles per hour to Kilometers per hour](https://calcbright.com/unit-converter/mph-to-kmh)
- [Megabytes to Gigabytes](https://calcbright.com/unit-converter/mb-to-gb)
- [PSI to Bar](https://calcbright.com/unit-converter/psi-to-bar)

## Popular currency pairs (rates refresh several times a day)
- [USD to EUR](https://calcbright.com/currency-converter/usd-to-eur)
- [USD to GBP](https://calcbright.com/currency-converter/usd-to-gbp)
- [USD to INR](https://calcbright.com/currency-converter/usd-to-inr)
- [USD to PKR](https://calcbright.com/currency-converter/usd-to-pkr)
- [EUR to USD](https://calcbright.com/currency-converter/eur-to-usd)
- [EUR to GBP](https://calcbright.com/currency-converter/eur-to-gbp)
- [EUR to INR](https://calcbright.com/currency-converter/eur-to-inr)
- [EUR to PKR](https://calcbright.com/currency-converter/eur-to-pkr)
- [GBP to USD](https://calcbright.com/currency-converter/gbp-to-usd)
- [GBP to EUR](https://calcbright.com/currency-converter/gbp-to-eur)
- [GBP to INR](https://calcbright.com/currency-converter/gbp-to-inr)
- [GBP to PKR](https://calcbright.com/currency-converter/gbp-to-pkr)
- [INR to USD](https://calcbright.com/currency-converter/inr-to-usd)
- [INR to EUR](https://calcbright.com/currency-converter/inr-to-eur)
- [INR to GBP](https://calcbright.com/currency-converter/inr-to-gbp)
- [INR to PKR](https://calcbright.com/currency-converter/inr-to-pkr)
- [PKR to USD](https://calcbright.com/currency-converter/pkr-to-usd)
- [PKR to EUR](https://calcbright.com/currency-converter/pkr-to-eur)
- [PKR to GBP](https://calcbright.com/currency-converter/pkr-to-gbp)
- [PKR to INR](https://calcbright.com/currency-converter/pkr-to-inr)

## About
- [About CalcBright](https://calcbright.com/about)
- [API & MCP for developers](https://calcbright.com/developers)
- [Contact](https://calcbright.com/contact): contact@calcbright.com