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Unit Price Calculator: Which Size or Brand Is Cheaper?

Compare two to five products by unit price and see which is cheaper per ounce, pound, liter or count, with the percent you save. Free.

How to use the Unit Price Calculator

  1. Enter the price and size of each product. Add a name if you want to tell them apart.
  2. Choose the unit for each size. Use the same kind of unit for every item: weight, volume or count.
  3. Enter packs if a price covers more than one package, and a coupon if you have one.
  4. Read which item is cheapest per unit, and how much more each of the others costs.

How the unit price calculator works

For each item, the calculator takes the price (minus any coupon) and divides it by the total amount: the size of one package times the number of packs. It converts everything to one base unit so different units can be compared.

Unit price = (price - coupon) / (size x packs)

It then ranks the items and shows how much more each costs per unit than the cheapest one.

Worked examples

Item Price Size Unit price
Large bottle $4.99 32 oz $0.156 per oz
Small bottle $2.99 16 oz $0.187 per oz
Small bottle with a $1.00 coupon $1.99 16 oz $0.124 per oz

With no coupon the large bottle is cheaper. With the coupon, the small one wins.

Unit conversions used

Unit Equals
1 pound 16 ounces
1 kilogram 35.274 ounces
1 gram 0.035 ounces
1 gallon 128 fluid ounces
1 quart 32 fluid ounces
1 liter 33.814 fluid ounces

Tips for comparing

  • Check the shelf tag. Most US grocery stores show a unit price, but they may use different units, such as per ounce on one item and per pound on another.
  • Compare in the same unit. This calculator shows per ounce, per pound or per 100 grams for weight, and per fluid ounce, per liter or per gallon for volume.
  • Perishable food saves money only if you use it in time.
  • Remember the extras: a membership fee, delivery fee or the cost of storage.

Is a warehouse membership worth it?

Unit price is only part of the answer. To see whether a membership pays for itself, use the Costco membership calculator or the Walmart+ calculator, and read whether a Costco membership is worth it.

Frequently asked questions

How do I calculate unit price?

Divide the price by the amount you get. A 32 oz bottle for $4.99 is about $0.156 per ounce, and a 16 oz bottle for $2.99 is about $0.187 per ounce, so the larger bottle costs about 17 percent less per ounce.

Is the bigger size always cheaper per unit?

Not always. Sales, coupons and different brands can make a smaller package cheaper per unit, which is why it is worth checking. A larger size only saves money if you use it before it spoils or expires.

Can I compare ounces with fluid ounces?

No. Ounces measure weight and fluid ounces measure volume, and they are not the same for most products. Compare weight with weight, volume with volume, and counts with counts.

How do I enter a multipack?

Enter the size of one package and the number of packs. A 12 pack of 12 oz cans is a size of 12 oz and 12 packs, which is 144 oz for one price.

Should I include a coupon?

Yes. Enter the coupon as dollars off, and the calculator takes it off the price before working out the unit price. A smaller package with a coupon can beat a larger one without.

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