Cost Per Item Calculator

A 4-pack of AA batteries costs $5.99 and a 20-pack costs $19.99. Per battery: $5.99 ÷ 4 ≈ $1.50 and $19.99 ÷ 20 ≈ $1.00.

The 20-pack is about 33% cheaper per battery — a third off each one, as long as you will use all twenty.

Use cost per item when every item is the same size and used the same way: eggs of the same grade, batteries of the same type, trash bags of the same capacity, tea bags, dishwasher tablets. If items differ in size or strength, compare by a unit printed on both packs — weight, sheets or loads — or by cost per use.

Cost per item = price ÷ number of items. For packs of packs — say 3 boxes of 20 tea bags — tap + Multipack: enter 20 as the size and 3 as the pack count, and the calculator uses 60 items.

Use whatever you use one at a time: eggs, batteries, trash bags, tea bags, dishwasher tablets, razor cartridges. Two packs are only comparable if the items are — 13-gallon and 30-gallon trash bags, or AA and AAA batteries, are not the same thing.

Sometimes items differ in size: large vs. medium eggs, or a “mega” roll vs. a regular roll. Then compare by a smaller unit printed on both packs — sheets, loads or weight. There are dedicated calculators for diapers, toilet paper, paper towels and laundry detergent.

Eggs come in 6, 12, 18 and 30 packs. 12 eggs for $3.29 is about $0.27 each; 18 for $4.49 is about $0.25 each. The 18-pack is about 9% cheaper per egg — worth it if you will use them before the date on the carton.

Batteries are a good example of why every size is worth checking:

Here the 20-pack is the cheapest per battery, and the 24-pack costs about 13% more each. Tap + Add product to compare up to four packs; the cheapest gets a check mark.