Free Unit Price Calculator

Compare price per unit to find the best deal.

Enter each option's price and size (in the same unit) to see the price per unit and which is the best value. Handy for comparing package sizes while shopping. Runs in your browser.

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What is the Unit Price Calculator?

The bigger package isn't always the better deal — supermarkets count on you assuming it is. The only way to know is price per unit, and doing that math in a busy aisle is exactly when it slips.

This unit price calculator compares options by their price per unit and tells you which is genuinely the best value.

Last updated: Aug 14, 2026

What does this tool do?

You enter each option's price and size (in the same unit), and it divides price by size to get the cost per unit.

It compares all the options and highlights the lowest price per unit — the real best value.

Key features

Price per unit

The number that actually matters.

Best-value highlight

Marks the cheapest per unit.

Any unit

Grams, ml, ounces, sheets, items.

Compare several

Add as many options as you like.

Private

Runs entirely in your browser.

Example

Input

$3.00 for 500g vs $5.00 for 1000g

Processing

Divide each price by its size.

Output

$0.006/g vs $0.005/g — the bigger pack wins.

Common use cases

Grocery shoppers — Compare package sizes.
Budgeters — Stretch every dollar.
Bulk buyers — Check if bulk really saves.
Parents — Compare nappies, wipes, snacks.
Small businesses — Compare supplier pricing.
Students — Shop on a tight budget.
Anyone in a store — Cut through pricing tricks.
Online shoppers — Compare listings by value.

Benefits

It reveals which size is truly cheapest.
It defeats 'bigger looks like a deal' tricks.
It works with any unit you choose.
It's fast enough to use in the aisle.

Tips

Always compare using the same unit for every option.
Convert first if sizes differ (e.g. kg to g) so the comparison is fair.
Cheapest per unit isn't always right if you'll waste the extra — buy what you'll use.
Watch for different units on shelf labels; recompute to be sure.
For multipacks, use the total count or total weight as the size.
Factor in quality, not just price, for things that vary.
Add a third option to compare bulk vs standard vs small.
Screenshots of shelf prices help you compare later.

Common mistakes to avoid

Comparing different units

Fix: Convert everything to the same unit first, or the per-unit prices aren't comparable.

Assuming bigger is cheaper

Fix: Not always — the calculator often shows the smaller size wins per unit.

Ignoring waste

Fix: The best per-unit deal isn't a saving if you throw half away; buy what you'll use.

Forgetting multipack counts

Fix: Use the total quantity across the pack as the size for a fair comparison.

How it works

1
Enter options
Price and size for each.
2
Use the same unit
Compare like with like.
3
See the winner
Best value is highlighted.

Frequently asked questions

It divides each item's price by its size to get the price per unit, then highlights the lowest — the best value.

Any, as long as you compare like with like — grams, millilitres, ounces, sheets, items — using the same unit for each option.

It divides each option's price by its size to get the price per unit, then highlights the lowest one.

Any — grams, millilitres, ounces, sheets, items — as long as you use the same unit for every option you compare.

Yes, if they differ. Convert to a common unit (e.g. all grams) so the per-unit prices are comparable.

Per unit, yes — but only buy the extra if you'll actually use it, or the saving is wasted.

As many as you like; add rows for each product.

No. The calculation runs entirely in your browser.

Conclusion

A unit price calculator turns confusing shelf prices into a clear best-value answer. Pair it with the discount and sales-tax calculators to work out the true final cost.