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About the unit price calculator
The big pack is not always the better deal. Shops price things in different sizes on purpose, so the only fair way to compare is the unit price — the price per ounce, per pound, per kilogram, per litre or per piece.
Enter the price and the size of two or more options. The calculator turns every one into a price per unit, marks the best value with a green tick, and tells you how much cheaper it is than the most expensive one. It even compares different units: a 16 oz jar against a 2 lb tub, or 500 g against 1 kg.
How to use it
- Enter the price of the first option
- Enter its size and pick the unit (g, kg, oz, lb, ml, L, fl oz, gal or pieces)
- Do the same for the second option
- Press Add another option to compare more
- The best value is marked — read how much you save
How unit price works
Unit price = price ÷ size.
| Small jar | Big jar | |
|---|---|---|
| Price | $3.49 | $5.99 |
| Size | 16 oz | 32 oz |
| Price per ounce | $0.218 | $0.187 |
The big jar costs 14% less per ounce — but only if you will use it all before it goes off.
When the bigger pack is NOT cheaper
- Special offers on small packs — a sale or a "2 for 1" can beat the big size.
- Shrinkflation — the pack looks the same, but there is less inside. Check the size every time.
- Food that goes off — half a big bag thrown away costs more than a small bag eaten.
- Multipacks — six single cans can cost more per litre than a big bottle, or less.
Frequently asked questions
How do I calculate the price per ounce?
Divide the price by the number of ounces. $4.80 for 12 oz is $4.80 ÷ 12 = $0.40 per ounce.
Can I compare grams with ounces?
Yes. Choose the right unit for each option — the calculator converts them all before comparing. 1 oz is 28.35 g, and 1 lb is 453.6 g.
What about fluid ounces?
Fluid ounces (fl oz) measure volume, like millilitres; ounces (oz) measure weight, like grams. Drinks and liquids use fl oz. You cannot compare a weight with a volume — the calculator tells you if you mix them.
How do I compare multipacks?
Use pieces (for example 12 rolls), or the total size (6 cans × 330 ml = 1,980 ml).
Is the shelf label unit price always right?
Usually, but shops sometimes use different units on neighbouring labels (per 100 g on one, per kg on the next). Typing the price and size here gives you a fair comparison.
Good to know
- Up to 10 options at once
- Your last comparison is saved in this browser
- Nothing you type is sent anywhere
Related tools
- Discount Calculator — the price after a percentage off
- Sales Tax Calculator — add or remove sales tax
- Percentage Calculator — any percentage question
- Subscription Cost Calculator — what your subscriptions really cost
- Unit Converter — ounces, grams and more
