Unit price is the cost per single unit of a product — per kilogram, per litre, per item, or per any other measurable quantity. It lets you compare products of different sizes on equal terms.
Unit price = Total price ÷ Quantity
For example, a 500g pack costing $3.50 has a unit price of $7.00 per kg. A 1.5kg pack costing $9.00 has a unit price of $6.00 per kg. The larger pack is better value despite costing more in total.
| Product | Size | Price | Unit price |
|---|---|---|---|
| Coffee A | 200g | $6.00 | $30.00/kg |
| Coffee B | 500g | $13.50 | $27.00/kg |
| Olive oil A | 500ml | $4.20 | $8.40/L |
| Olive oil B | 1L | $7.50 | $7.50/L |
| Paper towels A | 6 rolls | $5.40 | $0.90/roll |
| Paper towels B | 12 rolls | $9.60 | $0.80/roll |
Bulk buying is not always the cheapest option per unit. Supermarkets occasionally price smaller packs at a lower unit price than their larger equivalents — this is sometimes accidental and sometimes intentional. Promotional pricing, clearance stock, or own-brand vs name-brand comparisons can all produce surprising unit price results. Always calculate before assuming the larger size is the better deal.
Most supermarkets in the EU, UK, US, and Australia are legally required to display unit prices on shelf labels alongside the retail price. In the EU this is mandated under the Price Indication Directive. Despite this, the unit used varies — some shelves show price per 100g, others per kg, making direct comparison difficult without converting. This calculator lets you enter any quantity in any unit to get a consistent comparison.
Divide the total price by the quantity. If a 750ml bottle costs $5.25, the unit price is $5.25 ÷ 0.75 = $7.00 per litre.
Use whatever unit makes the comparison meaningful. For food, price per 100g or per kg is most common. For liquids, price per litre. For countable items, price per item. The important thing is to use the same unit for both products you are comparing.
Not always. Bulk packs are usually cheaper per unit, but promotional pricing, store brands, and clearance items can make smaller packs better value. Always check the unit price before assuming.
Most supermarkets display unit price on the shelf label, usually in smaller text below the retail price. The unit used varies — 100g, kg, litre, or per item — which can make comparison tricky without a calculator.
Yes, but you need to convert first. To compare price per 100g with price per kg, multiply the per-100g price by 10 to get the per-kg equivalent. This calculator handles the division — just make sure you enter quantities in the same unit for both products.