How to compare two packages
Enter each option’s total price, pack count, size per pack and unit. The price must cover all packs entered. For one bag, keep pack count at 1. For six 12 oz bags, enter 6 packs and size 12 oz.
Choose items to compare counted products. Two packs of six items means pack count 2 and items per pack 6: 12 items altogether. For a single 12-item pack, enter 1 and 12. Count each item once.
Select Calculate to compare. Try example fills the form without calculating; Reset clears your prices and quantities.
Method and example
Total quantity = pack count × size per pack
Unit price = total price ÷ total quantity in the comparison unit
Both quantities are converted to Package A’s unit. Mass units can be mixed; item counts can only be compared with item counts. Volume units and fluid ounces are not supported.
A 12 oz bag at $3 costs $0.25 per oz. A 1 lb bag at $3.60 contains 16 oz and costs $0.225 per oz. Package B costs 10% less per oz, with a unit price difference of $0.025 per oz. Its total purchase price is still $0.60 higher.
The percentage compares B with A: (B unit price − A unit price) ÷ A unit price × 100. Negative means B costs less; positive means B costs more. If A is free, this percentage is undefined. Equal unit prices are a tie, even when the purchase totals differ.
Assumptions and limits
Prices are in USD. No tax, shipping, fee or discount is added automatically; include relevant charges consistently in the entered prices. Compare products of similar quality and think about how much you will use. A lower unit price can still mean buying more than you need or wasting part of the package.
Mass conversion uses international avoirdupois units: 1 lb = 16 oz = 453.59237 g and 1 kg = 1000 g. The exact pound conversion is specified in NIST footnote 22; the NIST weight table confirms 16 ounces per pound. Troy ounces and fluid ounces are different units.
Prices may be $0 to $1,000,000 with two decimal places. Pack counts must be whole numbers from 1 to 100,000. Sizes may be 0.000001 to 1,000,000 with six decimal places; items must be whole numbers. Zero quantities are invalid.
The comparison uses unrounded prices. Unit prices and their differences show up to six decimal places; smaller positive values are shown as “less than $0.000001.” Percentage differences are rounded to two decimals, with tiny positive magnitudes identified as less than 0.01%. Nearly equal displayed rates may still have a winner.