Unit Price Calculator
The bigger pack isn't automatically the better deal — this compares two products by price per unit of size, which is the only fair way to judge value between differently sized options.
Inputs
Result
Item 2 is cheaper
0.009 vs 0.008 per unit
How the unit price calculator works
Unit price for each item = price ÷ size.
The item with the lower unit price is the cheaper option per unit.
Worked example: Item 1 at 4.5 for 500 g, Item 2 at 7.2 for 900 g
- Item 1 unit price = 4.5 ÷ 500 = 0.009 per gram.
- Item 2 unit price = 7.2 ÷ 900 = 0.008 per gram.
- 0.008 < 0.009, so Item 2 is cheaper per gram despite costing more overall upfront.
Common mistakes to avoid
Comparing total price alone without accounting for different pack sizes
A higher total price for a much larger pack can still be the better deal per unit — total price only tells you the full cost, not the value, unless both items are the exact same size.
Mixing units between the two items, like grams for one and ounces for the other
Both size fields need to be in the same unit for the comparison to be valid — comparing 500 g against 32 oz without converting one to match the other produces a meaningless result.
Frequently asked questions
Why do many stores already show a 'price per unit' on shelf labels?
It's specifically designed to let shoppers make exactly this kind of comparison without doing the math themselves — this calculator does the same thing for situations, like online shopping, where that label isn't shown.
Does a lower unit price always mean I should buy that option?
Purely on cost-efficiency, yes — but consider whether you'll actually use the larger size before it expires or goes to waste, since a lower unit price only saves money if the product gets fully used.
Can this compare items in completely different units, like a liquid in litres versus one in millilitres?
Convert both to the same unit first — entering mismatched units directly gives a comparison that looks valid but isn't.
How is this related to the Pizza Value Calculator?
Same underlying idea — comparing price relative to the actual quantity received — but the pizza tool specifically accounts for circular area geometry rather than a simple linear size figure.
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