🛒 Unit Price Calculator
Enter the price and size of two or three products, even in different units like grams and pounds, and see which costs least per 100 g, per 100 ml or per item.
Quick answer: Unit price = price ÷ size. A 500 g pack at $3.99 costs $0.80 per 100 g; a 1 kg pack at $7.20 costs $0.72 per 100 g, so the larger pack is cheaper.
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Unit Price Calculator inputs
Result
Best value
Product B
$0.72 per 100 g
| Product A | $0.80 per 100 g |
| Product B | $0.72 per 100 g |
Product B is 10% cheaper per unit than the dearest option.
Comparison
| Product | Price | Unit price per 100 g | Versus best |
|---|---|---|---|
| Product A | $3.99 | $0.80 | +11% |
| Product B | $7.20 | $0.72 | Best value |
How unit price is calculated
Divide the price by the amount you get, after converting every size to the same base unit. This calculator uses 100 g for weight, 100 ml for volume and one item for counts.
Unit price = Price ÷ Size × base amount
Example: Product A is 500 g for $3.99, which is 3.99 ÷ 500 × 100 = $0.80 per 100 g. Product B is 1 kg (1,000 g) for $7.20: 7.20 ÷ 1,000 × 100 = $0.72 per 100 g. Product B is 10% cheaper per unit.
Unit conversions used
| Unit | Equals |
|---|---|
| 1 kg | 1,000 g |
| 1 oz | 28.35 g |
| 1 lb | 453.59 g |
| 1 L | 1,000 ml |
| 1 US fl oz | 29.57 ml |
| 1 US gal | 3,785.41 ml |
Shopping tips
- Compare the unit price on the shelf label, but check the unit; some shops switch between per kg and per 100 g.
- Check the net weight after draining for canned foods.
- Only buy bulk if you will use it before it expires.
Frequently asked questions
Is the bigger package always cheaper per unit?
No. Larger packs are often cheaper, but promotions and shelf-price quirks can make a smaller pack better value, which is why you should compare the unit price.
Can I compare ounces with grams?
Yes. Each product has its own unit and everything is converted to a common base (100 g, 100 ml or per item) before comparing.
Why can I not compare weight with volume?
A gram and a millilitre measure different things, and conversion depends on the product density, so mix only weights with weights and volumes with volumes.
Does the cheapest unit price always mean the best deal?
Not if you will not use it all. A bulk pack that spoils or is thrown away costs more than the smaller pack you finish.
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