Unit Price Comparison Calculator
Find out if the bigger size is really cheaper. Compare any number of package options across mixed units (g, kg, oz, lb, ml, L, fl-oz, count), normalize to a common base, highlight the best value, and adjust for waste.
How to use this tool
- Add each package: a label, its price, its size, and the size unit.
- Optionally enter a waste % for items you won’t fully use before they spoil.
- Add at least two options to see the comparison.
- Read the price-per-unit column and the green BEST flag; other rows show how much more they cost.
- Copy the page URL to share the full comparison.
The “family size” is supposed to be cheaper, but supermarkets love to price packages in different units to make comparison hard — one in ounces, one in grams, one “per count.” This tool does the conversion for you. Add as many options as you like in any mix of units and it normalizes every one to a common base (per 100 g, per liter, or per item) so you can compare apples to apples.
It then highlights the best value and shows exactly how much more expensive each other option is as a percentage. The invented twist is the waste factor: if you’ll throw out 30% of the giant bag of spinach before you use it, that bulk “deal” isn’t one. Enter a waste percentage and the effective price-per-unit rises to reflect what you’ll actually consume — which frequently flips the winner. Share the URL to send your whole comparison to someone at the store.
Frequently asked questions
- Can I compare ounces against grams?
- Yes. Weight units (g, kg, oz, lb) are all converted to grams and shown per 100 g; volume units (ml, L, fl-oz) are converted to liters and shown per liter; count is shown per item. The tool warns you if you mix categories, because weight, volume, and count aren’t directly comparable.
- How does the waste factor work?
- If you enter a waste percentage, the tool reduces the usable amount by that share and divides the full price over only what you’ll actually use. A $6 bag you waste 25% of effectively costs the same per usable unit as an $8 bag with no waste — so the “cheaper” big size can lose.
- Why does the bigger package sometimes lose?
- Bulk is only a deal if the per-unit price is genuinely lower and you use it all. Promotions on small sizes, club-card prices, and especially spoilage can make the smaller package the better real-world value. This tool surfaces that.