Unit Price Calculator
Shelf tags make the package price loud and the per-unit price small, which is exactly backwards for deciding. Enter one package's price and quantity for its unit price — or fill in both options and the calculator names the cheaper one and says by how much per unit.
Compare two package sizes
Example: 3.89 for 24 oz vs 5.49 for 36 oz — the larger box is 5.91% cheaper per ounce.
One division that stores hope you skip
Unit price = package price ÷ quantity. A 4.5 six-pack is 0.75 per can; 3.89 for 24 oz is 0.1621 per ounce while 5.49 for 36 oz is 0.1525 — making the larger box 5.91% cheaper per ounce. Those figures are computed at build time by the same engine as the form, so the worked example is guaranteed to match what the calculator would tell you.
The same-units rule
The comparison is only as good as its denominators. Quantities must be in the same unit before dividing: a pound jar compared against an ounce jar needs the pound converted to 16 oz first, and "per 100g" shelf labels need both packages on the 100g basis. When labels disagree, convert the quantity — never the computed unit price — and re-run the division.
When cheap per unit isn't cheap
Unit price measures cost, not value: the giant tub only wins if you finish it before it expires, and a promotion can flip the ranking overnight — apply any discount to the affected package first, then compare. If a package shrank while its price held (the quiet trick sometimes called shrinkflation), the price change calculator can quantify the effective increase per unit you're now paying.
Frequently asked questions
What is a unit price?
The price divided by the quantity: a 4.5 six-pack costs 0.75 per can. Reducing every package to the same denominator is the only fair way to compare a 24 oz jar against a 36 oz one.
What if the two packages use different units?
Convert one of them first — comparing a per-ounce price against a per-pound price makes the smaller unit look sixteen times cheaper than it is. Put both quantities in the same unit (all ounces, all grams, all count) and the comparison becomes honest.
Is the bigger package always the better deal?
Usually, but not reliably — stores sometimes price the large size at a higher unit cost (a "quantity surcharge"), betting shoppers assume bulk is cheaper. In the example above, the larger box does win: 0.1525 against 0.1621 per ounce. The calculator checks instead of assuming.
Should I compare before or after a coupon?
After — a discount changes the effective price of one option and can flip the winner. Apply the coupon or promotion to that package's price first, then compare the resulting unit prices.
What does the savings percentage refer to?
The gap between the two unit prices, measured against the more expensive one. "7% cheaper per unit" means every ounce or item bought at the better price costs 7% less than it would have at the other.
Comparisons happen entirely on your device; nothing is uploaded. Unit prices display with up to four decimal places so close contests stay visible — rounding rules are on the methodology page.