How this calculator works
- Step 1Price₹ per packWhat each pack costs.
- Step 2Unit priceprice ÷ quantityCost of one gram, ml or piece.
- Step 3Comparelower winsAnd by how much.
Packs come in different sizes, so the sticker price does not tell you which is cheaper. Dividing the price by the quantity gives the unit price, which can be compared directly.
The calculator also checks equal value exactly, by cross-multiplying, so two packs with the same unit price are reported as the same.
Worked example: 500 g or 1 kg
- Unit price
price ÷ quantity
- Pack A99 ÷ 500₹0.1980 a gram
- Pack B180 ÷ 1,000₹0.1800 a gram
- Per 100 g₹19.80 vs ₹18.00
- Pack B cheaper by9.1%
Read the result
Bigger is not always cheaper: ₹85 for one against ₹399 for five makes the single pack 6.1% cheaper per unit.
- Detergent per load$0.2342 vs $0.199964 loads for $14.99 against 80 for $15.99: the larger pack wins.
- ₹10 for 3, ₹20 for 6Same valueExactly the same unit price.
Assumptions and limits
- Same unitGrams with grams, ml with ml.
- Same productQuality and brand matter too.
- WasteA big pack is dearer if part is thrown away.
- OffersEnter the price after any discount.
Related shopping tools
Price per unit is the fairest way to compare packs. Discounts and tax change the price itself.
To apply one or more discounts, use the discount calculator. The GST calculator adds or removes tax, and the unit converter puts packs into the same units.
Common mistakes
Mistake: Comparing 1 kg with 500 ml as if the same.
Instead: Convert to one unit first.
Mistake: Assuming the family pack is cheaper.
Instead: Work out the unit price for both.
Checking the method
A separate script compares every pair with exact fractions and cross-multiplication and reproduces OpenStax Examples 5.66 and 5.67.
Read how we test our calculators, or browse more everyday tools.