How this unit price calculator works
The unit price is what one standard amount of a product costs — one gram, one millilitre or one item. You find it by dividing the total price by the quantity: unit price = total price ÷ quantity. Because packs come in all sorts of sizes, the unit price is the only fair way to compare value across them.
To compare fairly you have to use the same measurement family. This tool converts weight (ounces, pounds, grams, kilograms) to grams, volume (fluid ounces, millilitres, litres) to millilitres, and count to items. If one row uses a different family from the others — say weight against volume — those can't be compared directly, so the calculator compares only same-family rows and tells you which it left out.
| Item | Price | Size | Per 100 g | Verdict |
|---|---|---|---|---|
| Item A | $3.00 | 500 g | $0.60 | 20% more |
| Item B | $5.00 | 1 kg | $0.50 | Best value |
| Item C | $1.80 | 250 g | $0.72 | 44% more |
Reference note: 1 oz ≈ 28.35 g, 1 lb ≈ 453.59 g, 1 kg = 1,000 g; 1 fl oz ≈ 29.57 ml, 1 l = 1,000 ml. Conversions use US fluid ounces. Always check the actual shelf quantity, as pack contents can differ from the advertised size.
Frequently asked questions
- How do I calculate unit price?
- Divide the total price by the quantity: unit price = total price ÷ quantity. For example, $4.50 for 750 g is $0.006 per gram, or $0.60 per 100 g.
- How do I compare prices of different sizes?
- Convert each item to the same base unit, then divide the price by that quantity. Compare like with like — weight with weight, volume with volume — and the lowest cost per base unit wins.
- Is the bigger size always cheaper?
- No. The larger "value size" is often cheaper per unit, but promotions, multipacks and packaging can make a smaller pack a better deal. Always compare the cost per unit.
- How do I compare price per ounce vs per gram?
- Both measure weight, so convert to a common base — one ounce is about 28.35 grams. This calculator converts ounces, pounds, grams and kilograms to grams so you can compare them directly.
- What is cost per unit?
- Cost per unit is the price of one standard amount — one gram, one millilitre or one item — found by dividing the total price by the quantity. It is the fairest way to compare different pack sizes.
- How do I find the best grocery value?
- Work out the cost per unit for each option and pick the lowest. Shelf labels often show a unit price, or you can enter each item here to compare per ounce, per 100 g or per litre.