Reckonary / Everyday / Unit price
Verdict
The price on the shelf rarely tells you which package is the better deal. A bigger box costs more but might give you far more for your money — or far less. The fix is the unit price: the cost of a single unit, like one ounce or one item. Enter the price and quantity for two options and this calculator tells you which one wins, and by how much.
For each option it divides the price by the quantity to get the unit price, then compares the two. Because unit prices are often a tiny fraction of a dollar, the result is shown to four decimal places so close calls don't look identical. The option with the lower unit price is the cheaper one, and the "Cheaper by" figure shows the gap as a percentage of the pricier option.
Option A is $5 for 500 units, so it costs $0.0100 per unit. Option B is $8 for 1,000 units, which works out to $0.0080 per unit. Even though B has the higher sticker price, it's the better buy — its unit price is 20% lower. That's the kind of swap that's easy to miss at a glance but adds up over a full cart.
What is a unit price?
It's the price for a single unit of whatever you're buying — per ounce, per gram, per sheet, per item. Dividing the price by the quantity puts two differently sized packages on the same footing so you can compare them fairly.
Do both products have to use the same unit?
Yes. Compare ounces to ounces or grams to grams. If one label is in ounces and the other in grams, convert one of them first, otherwise the comparison isn't apples to apples.
What does 'Cheaper by' mean?
It's how much less the winning unit price is, as a percentage of the pricier one. If A costs 20% less per unit than B, you'd see 'Cheaper by 20%'.
Is the bigger package always cheaper?
Not always. Larger sizes often have a lower unit price, but stores sometimes price small or sale items below the bulk option. Checking the unit price is the only way to know for sure.
Last reviewed June 2026.