Quick Answer
This price per unit calculator compares up to four items on a common unit price at https://practicalwebtools.com/finance/price-per-unit-calculator. Enter price, quantity, and unit (oz, lb, g, kg, mL, L, count, roll, or sheet) for each; it converts with exact factors — 1 lb is 453.59237 g and 1 oz is 28.349523125 g — marks the cheapest per unit, and shows the savings percent. 6 for 500 g: 0.3402/oz.
How It Works
Enter the first item: price, quantity, and unit — oz, lb, g, kg, mL, L, count, roll, or sheet
Add up to three more items, each in its own packaging unit; weight converts with weight and volume with volume
Read every unit price in one common unit, with the cheapest item highlighted and each other item marked with its percent above the best
Check the savings percent to see what the best item saves you versus the most expensive option
Key Facts
- Compares two to four items at once and highlights the cheapest per unit
- Nine units supported: oz, lb, g, kg, mL, L, count, roll, and sheet
- Weight and volume conversions use exact definitions — 1 lb = 453.59237 g, 1 oz = 28.349523125 g, 1 kg = 1000 g, 1 L = 1000 mL
- Weight-versus-volume and roll-versus-sheet mixes are flagged incomparable instead of being ranked dishonestly
- Each item shows its unit price in the common unit, its percent above the best, and the savings percent for the winner
- Shelf-tag formatting: unit prices under 0.3125/oz
- Built for the "is this deal actually good" moment — Black Friday multipacks and warehouse sizes included
- Runs entirely in this browser tab — you can watch the Network tab stay silent while you type
Frequently Asked Questions
How do I calculate price per unit?
Divide the total price by the total amount in a single unit: a 5 ÷ 16 = $0.3125 per oz. When packages use different units, convert them to one unit first — 500 g is 500 ÷ 28.349523125 = 17.637 oz — then divide each price by its own converted amount. The calculator does both steps and reports every price in the same unit.
Why can it compare ounces to grams but not ounces to milliliters?
Ounces and grams are both weight, so an exact definition connects them: 1 lb is 453.59237 g and 1 oz is 28.349523125 g. Ounces (weight) and milliliters (volume) measure different things — linking them needs a density, which varies product to product. The calculator refuses the comparison instead of quietly assuming water.
Can I compare paper goods sold per roll and per sheet?
Only after you put them in the same unit. Rolls and sheets are discrete counts with no fixed conversion — a roll can hold any number of sheets — so items entered with different discrete units come back flagged incomparable. If the box states sheets per roll, do that multiplication yourself and enter every item in sheets (or in counts of rolls); then the comparison is exact.
Which item gets highlighted, and what is the savings percent?
The item with the lowest price per common unit is highlighted with a best-price badge. Each other item shows how many percent above the best it lands, and the headline savings percent is what you save buying the best item instead of the most expensive comparable one — 20% when a 0.625/roll one.
Does the lowest unit price always mean the better buy?
For pure price arithmetic, yes — that is exactly what it computes. It cannot see quality, storage space, expiry dates, or whether you needed the item at all. A lower unit price on something you will throw away is still a loss; use the math to compare value, and your own judgment to decide the purchase.
Why did you build this instead of reading the shelf tag?
Shelf tags go missing, use different units on purpose, and vanish entirely online — especially during Black Friday, when "value size" is a marketing term, not a math result. I built this to settle the arithmetic in seconds: exact conversion factors, up to four items, everything running in this browser tab where you can watch the Network tab stay silent. Nothing you price is uploaded.