Price per unit calculator
Price per kilogram, litre or piece, and a comparison of two packs.
Fill in the fields and the result will appear here automatically.
Converts a pack price to a kilogram, litre or piece and compares two unit prices. 150 for 0.5 kg is 300 per kg versus 260 for 1 kg: a 40 difference per kg, with the first about 15.4% higher. It compares price for quantity, not quality or overall purchase value.
How it works
Formula and logic
Unit price = price / amount. The sign of priceA×amountB − priceB×amountA selects the cheaper pack without an arbitrary “almost equal” tolerance. Overpayment is the absolute unit-price difference. Money rounding is for display, so close prices can look identical. Comparison uses decimal price and amount values before display rounding.
Example
150 for 500 g: enter 0.5 kg to get 300 per kg. A 260 pack containing 1 kg is 40 per kg cheaper; buying 2 kg makes an 80 difference.
Fields and units
- What to do — list option
- Unit — list option
- Pack price — $
- Amount in the pack — selected unit
- Price of pack A — $
- Amount in pack A — selected unit
- Price of pack B — $
- Amount in pack B — selected unit
How to use
- — Choose one unit: kg, litres or pieces. Convert 500 g to 0.5 kg before entry; no automatic conversion is performed.
- — Enter a positive price and amount in single mode; switch to comparison for two packs.
- — Use one selected unit and one currency for both packs, with the actual price after discounts.
- — For individual items, enter their actual count; also consider quality, shelf life and the quantity you need.
Method and limitations
- Calculation method
- Formula and logic
- Limitation
- Arithmetic in one currency and one chosen unit. Exchange rates, quality, delivery and product waste are not included.
FAQ
Why reduce prices to a unit?
Because packs are rarely the same size and cannot be compared at a glance. Reducing to a kilogram or a litre makes the prices comparable.
What goes in the amount field?
The quantity in the unit selected above: convert grams to kilograms and millilitres to litres first.
What does the overpayment show?
How much dearer one unit is in the less favourable pack. Multiply it by the quantity you need to see the full overpayment.
Are discounts included?
No — enter the final price you pay at the till, with any discount already applied.