Price-Per-Unit Calculator
Different pack sizes are designed to make price comparison hard. Enter the price and size of two options and this tool does the per-unit maths instantly, so you can see which one is genuinely cheaper — not just which has the smaller sticker price.
Why price-per-unit is the only fair comparison
Supermarkets and online stores rarely make it easy to compare two products head-to-head. One is sold in grams, another in ounces; one comes in a 6-pack, another in a 10-pack; a "bonus size" looks generous until you do the maths. The unit price — the cost of a single gram, ounce, millilitre or count — strips all of that away and lets you compare like with like.
The headline price is almost meaningless on its own. A larger container usually looks like better value because it costs more in total, but that is not the same as costing less per unit. Retailers know this, which is why the biggest size is not always the cheapest per gram — sometimes the mid-size or even a multi-buy on the small size wins.
Tip: in many regions, shelf labels are legally required to show a unit price in small print. Use it — and when it is missing or the units don't match, this calculator fills the gap.
How to use this calculator
- Enter the total price and size of each product. The size can be anything — grams, ounces, sheets, capsules, loads — as long as you use the same measure for both.
- Add an optional unit label (like "g" or "oz") so the result reads naturally.
- The tool shows the cost per unit for each and tells you which is cheaper, and by how much.
For more ways to judge real value, see our guide on how to spot a good deal and the cost-per-use calculator, which factors in how long something lasts — not just what it costs today.
FAQ
How do I calculate price per unit?
Divide the total price by the number of units in the pack. For example, a $4.99 bottle holding 500 ml works out to about $0.010 per ml. To compare two products fairly, calculate the price per unit for each using the same measure, then pick the lower figure. This calculator does that automatically for two products at once.
Is the bigger size always cheaper per unit?
No. Bigger packs usually cost more in total, which makes them look like better value, but the price per unit is often similar to — or occasionally higher than — a smaller size. 'Bonus' and 'family' sizes are sometimes priced to seem generous without actually being cheaper per unit, so it always pays to check rather than assume.
What units can I compare?
Any units, as long as you use the same one for both products. Grams, ounces, millilitres, litres, sheets, tablets, loads, or simple counts all work. The key rule is consistency: don't compare a price-per-gram against a price-per-ounce. If the two products are sold in different units, convert one first so both use the same measure.
Does a lower unit price always mean it's the better buy?
Usually, but not always. A lower unit price is the better deal only if you will actually use the product before it expires or goes stale, and if you have room to store it. Buying a huge, cheaper-per-unit pack you can't finish wastes money. For durable goods, also weigh how long each option lasts using our cost-per-use calculator.