How it works
Enter the price and quantity of two packs that use the same unit — grams, millilitres, pieces or any other. The calculator divides each price by its quantity and shows which pack costs less per unit.
Unit price = price ÷ quantity
Worked example
- Pack A: 5,000 for 500 g → 10 per gram.
- Pack B: 9,000 for 1,000 g → 9 per gram, so B is cheaper.
- The difference is 1 per gram, which is 10% off the more expensive unit price.
Tips
- Both quantities must use the same unit. Convert 1 kg to 1,000 g before comparing with a 500 g pack.
- A bigger pack is not always cheaper per unit — multipacks and small sizes often hide the real price.
- Compare the saving against what you actually use up before the expiry date.
- Results are rounded for display; the comparison itself uses the full precision.
Standards and sources
- Unit pricing follows the standard definition (total price ÷ total quantity)
- Currency symbols and decimal places follow ISO 4217 (Korean won and Japanese yen have no decimal places)
Last reviewed October 12, 2026
Frequently asked questions
How do I compare two packs of different sizes?
Enter each price with its quantity in the same unit — for example 5,000 for 500 g and 9,000 for 1,000 g. The calculator shows 10 and 9 per gram, so the second pack is cheaper.
Can I compare grams with kilograms?
Not directly. Convert to the same unit first: 1 kg is 1,000 g. Comparing a 500 g pack with a 1 kg pack means entering 500 and 1,000 as the quantities.
What does the saving percentage mean?
It is the per-unit difference divided by the more expensive unit price. If the unit prices are 10 and 9, the difference of 1 is 10% of 10.
The bigger pack is always cheaper, right?
Often, but not always. Small packs on sale and multipack pricing can beat the big pack per unit, which is exactly what this comparison catches.
Should I always buy the cheaper per-unit pack?
Not necessarily. Check whether you will use it all before the expiry date — food waste wipes out the unit-price saving.