How to calculate unit price
The unit price is what you pay for one unit of a product, such as one ounce, one gram or one item. To find it, divide the price by the quantity:
18 oz box for $4.29 → $4.29 ÷ 18 = $0.238 per oz
28 oz box for $6.49 → $6.49 ÷ 28 = $0.232 per oz ← slightly cheaper
The tricky part is when sizes use different units, such as grams against ounces, or a 6-pack of 12 oz cans against a 2-litre bottle. This calculator converts everything to the same unit first, so you can compare them directly.
Tips for comparing prices in the store
- Check the shelf tag, then double-check it. Shelf unit prices sometimes use different units for neighbouring products, such as per ounce against per count.
- Bigger is not always cheaper. Sale prices on smaller sizes often beat the bulk pack.
- Count multi-packs properly. A 12-pack of 16.9 fl oz bottles is 202.8 fl oz in total. Use the Pack field.
- Only buy bulk you will use. Food that spoils before you finish it cancels out the saving.
Questions
How do you calculate unit price?
Divide the price by the quantity. A 24 oz jar for $4.80 is $4.80 ÷ 24 = $0.20 per ounce.
Can I compare grams with ounces?
Yes. Pick each product's own unit and the calculator converts them (1 oz = 28.35 g, 1 lb = 453.6 g). The same works for fluid ounces, millilitres and litres.
Can I compare weight with volume?
Not reliably, because the density of each product differs. Compare products measured the same way, by weight, by volume or by count.
Is the lowest unit price always the best buy?
Not always. It is only a saving if you use it all before it spoils, and if you have the space to store it.
Conversion factors from NIST unit conversion.