Unit Price Calculator
Compare products by price per unit to find which is genuinely better value, or convert one package price into a standard unit.
What the Unit Price Calculator does
Unit price divides cost by quantity, which is the only honest way to compare package sizes. Bigger packs are usually but not always cheaper per unit — retailers regularly price the middle size worst. Use "Compare" to put two or three packages side by side, or "Convert" when you only have one package and want its price per gram, kilogram, litre, ounce or pound — the unit a shelf label or recipe actually uses.
Formula
Unit price = Total price ÷ QuantityFor the single-package mode: scale the result to the chosen reference unit
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| What do you want to do? | one of 2 options | Yes | — |
| Price of option A | selected currency | In some modes | Accepts more than 0. Shown What do you want to do? is Compare 2–3 packages. |
| Quantity in option A | number | In some modes | Accepts more than 0. Shown What do you want to do? is Compare 2–3 packages. |
| Price of option B | selected currency | In some modes | Accepts more than 0. Shown What do you want to do? is Compare 2–3 packages. |
| Quantity in option B | number | In some modes | Accepts more than 0. Shown What do you want to do? is Compare 2–3 packages. |
| Price of option C | selected currency | Optional | Accepts 0 or more. Shown What do you want to do? is Compare 2–3 packages. |
| Quantity in option C | number | Optional | Accepts 0 or more. Shown What do you want to do? is Compare 2–3 packages. |
| Package price | selected currency | In some modes | Accepts more than 0. Shown What do you want to do? is Convert one package to a standard unit. |
| Package quantity | number | In some modes | Accepts more than 0. Shown What do you want to do? is Convert one package to a standard unit. |
| Unit | one of 7 options | In some modes | Shown What do you want to do? is Convert one package to a standard unit. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose What do you want to do? and Currency.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
A 500 g pack for $4.20 against a 1.2 kg pack for $9.60.
- Mode
- Compare
- A price
- 4.20
- A quantity
- 500
- B price
- 9.60
- B quantity
- 1200
$0.0084 versus $0.0080 per gram — the larger pack is about 4.8% cheaper per unit.
Reading the result
- Reducing every option to a price per standard unit is the only reliable way to compare package sizes across brands.
- The larger pack is not always cheaper per unit — multi-buys and premium sizes frequently invert the expected order.
Assumptions and limitations
- Comparison assumes the products are equivalent. Concentration, drained weight and quality differences are not captured by price per unit alone.
Common mistakes
- Comparing a weight-based price against a volume-based one. Grams and millilitres only coincide for water-like densities.
- Ignoring what will actually be used. A cheaper unit price is no saving if the larger pack spoils first.
Frequently asked questions
Is the biggest pack always cheapest per unit?
No. Check every time. And a lower unit price is no bargain if you will not use it before it spoils.
Which unit should I compare in?
Whichever the shelf label uses — usually per 100 g or per kg for food, per litre for liquids. Consistency matters more than the choice itself.