TOOLWhich one is actually cheaper?
Bigger packs aren't always the better deal, and "sale" prices can hide worse value. The only fair comparison is cost per unit. Enter each product's price and size — even in different units — and this tool converts both to a common base and tells you the genuinely cheaper buy, and by how much.
How it works
Weights are compared per 100 g, volumes per 100 ml, and countable items per piece. Because everything is normalised to a base unit, you can pit a 500 g bag against a 1 kg one, or ounces against grams, and still get a fair result.
Example
A $4.50 bag of 500 g is $0.90 / 100 g. A $7.00 bag of 1 kg is $0.70 / 100 g — so the bigger bag is about 22% cheaper per unit, even though it costs more up front.
Adding tax at the till? See the sales tax calculator. Working out a sale price? Try the discount calculator.
Comparisons are only valid between products measured the same way (weight vs weight, volume vs volume). Quality, brand and quantity you'll actually use also matter — cheapest per unit isn't always the best buy.
Frequently asked questions
How do you calculate unit price?
Divide the price by the size in a common unit. A $4.50 pack of 500 g costs $0.009 per gram, or $0.90 per 100 g. Comparing the per-unit price of two items shows which is cheaper regardless of pack size.
Can I compare different units like grams and ounces?
Yes, as long as they measure the same thing. This calculator converts weights and volumes to a common base, so you can compare a product sold in ounces against one sold in grams.
Why is unit price useful when shopping?
Bigger packs are not always cheaper per unit, and sale prices can be misleading. Comparing cost per unit reveals the genuinely better value between two options.