How unit pricing works
Unit price strips away pack size so you can compare products fairly. It's simply the total price divided by the quantity:
unit price = total price ÷ size
The product with the lower unit price gives more for your money — provided you're comparing the same unit (price per gram, per litre, per sheet, per wash). Bigger packs are usually, but not always, cheaper per unit; this tool shows the actual numbers so you don't have to assume.
Worked example
Product A: $3.50 for 500 g. Product B: $5.00 for 750 g. Which is better value?
A: 3.50 ÷ 500 = $0.0070 per gram (70¢ per 100 g).
B: 5.00 ÷ 750 = $0.00667 per gram (66.7¢ per 100 g).
Winner: Product B, about 4.8% cheaper per gram.
The golden rule: compare like with like
Unit pricing only works when both products are measured the same way. Before you compare, convert to a common unit:
| If you have... | Convert to... |
|---|---|
| Grams and kilograms | Grams (1 kg = 1,000 g) |
| Ounces and pounds | Ounces (1 lb = 16 oz) |
| Millilitres and litres | Millilitres (1 L = 1,000 ml) |
| Sheets, washes, count | The number of items (rolls of 200 vs 160 sheets) |
Enter the size in the same unit for both products and the comparison is valid. The unit converter can help if one pack is metric and the other imperial.
Three supermarket pricing traps
- The "bigger is cheaper" myth. Family packs are often better value, but retailers sometimes price the large size higher per unit, betting you won't check. Roughly one in ten comparisons surprises people.
- Mismatched shelf-label units. Stores may show "per 100 g" on one product and "per item" on the next, defeating a quick glance. Recompute on a common unit.
- Buying more than you'll use. A lower unit price on a perishable is no saving if half of it spoils. Factor in waste, not just the sticker.
Tip: for everyday shopping, "price per 100 g" or "price per litre" is easier to compare than tiny per-gram figures. Multiply this tool's per-unit result by 100 (or 1,000) for a friendlier number.