Answerivo

Everyday Math

Unit Price Comparison Calculator

The bigger package or the lower price is not always the cheaper option once you account for how much is actually inside. Enter the price and quantity for each product, choose their units, and this calculator converts everything to a common base so you can compare like for like.

Step 1

Enter your numbers

Item 1
Item 2
Item 3 (optional)
Optional
Optional
Optional

Results update as you type. Nothing you enter leaves your device.

Step 2

Results

Fill in the form and your results appear here instantly.

Estimates only. Verify important figures against your own records before acting on them. See our disclaimer.

What this calculator includes

What you enter

  • Item 1 price
  • Item 1 quantity
  • Item 1 unit
  • Item 2 price
  • Item 2 quantity
  • Item 2 unit
  • Item 3 price (optional)
  • Item 3 quantity (optional)
  • Item 3 unit (optional)

What you get back

  • Best value
  • Item 1 price per gram
  • Item 2 price per gram
  • Cheaper by

How this calculation works

Unit price strips out pack size so different quantities and units can be compared directly, by converting every quantity into the same base unit before dividing.

  • Convert each item's quantity to a common base unit within its family (grams for weight, milliliters for volume, each for count)
  • Unit price = price ÷ quantity in base units
  • The item with the lowest unit price is the best value
  • Percent cheaper = (next-best unit price − best unit price) ÷ next-best unit price × 100

Worked example

A 12 oz package for $3.49 versus a 32 oz package for $8.29.

  1. 1Item 1: 12 oz × 28.3495 g/oz = 340.19 g, so the unit price is $3.49 ÷ 340.19 g ≈ $0.0103 per gram.
  2. 2Item 2: 32 oz × 28.3495 g/oz = 907.18 g, so the unit price is $8.29 ÷ 907.18 g ≈ $0.0091 per gram.
  3. 3The larger pack wins: $0.0091 versus $0.0103 per gram, about 11% cheaper per unit.
  4. 4Both items must be measured the same way — weight against weight, or volume against volume — so the calculator blocks a weight-versus-volume mismatch rather than returning a meaningless figure.

Frequently asked questions

Can I compare a liquid priced by weight to one priced by volume?
Not directly, unless you know the product's density to convert between the two — a fluid ounce of water and a fluid ounce of honey do not weigh the same. Enter both items in the same measurement family (both weight or both volume) for an apples-to-apples answer.
Why does the calculator reject my units?
It checks that every item you fill in belongs to the same family — weight, volume, or count — because dividing a weight price by a volume quantity produces a meaningless number. Switch one item's unit to match the others.
What does 'count' mean as a unit?
Use count for items sold by the piece — diapers, eggs, capsules — where the number of items, not their weight or volume, is what you are paying for.
Does this account for quality differences?
No. It only compares price per unit of quantity. A cheaper unit price is not automatically the better purchase if the products differ in quality, concentration, or usage rate.
How precise are the unit conversions?
Weight and volume conversions use standard exact factors (1 lb = 453.59237 g, 1 oz = 28.3495 g, 1 L = 1,000 mL), so results are accurate to the precision of the prices and quantities you enter.

Disclaimer

This calculator returns estimates based only on the values you enter. It does not account for taxes, financing terms, local regulations, or conditions specific to your operation, and it is not accounting, legal, tax, or investment advice. Confirm any figure that carries real cost before you rely on it.

Calculations run entirely in your browser and the numbers you type are never sent to us or stored. Read how Answerivo calculators are built.

Formulas and worked example last reviewed .