Unit Price FAQ
Short, practical answers to the questions shoppers actually ask about comparing pack sizes. Every answer follows the same rule this site is built on: compare like with like, in one standard unit, and let the numbers — not the packet — decide.
How do I calculate unit price?
Divide the shelf price by the total quantity in the pack. For a multipack, multiply pack count by the size of one pack first: 2 × 500 g = 1,000 g, so £5.00 ÷ 1,000 g = £0.005 per gram, or £5.00 per kg. The unit price calculator does this for you, including unit conversions.
Is the bigger pack always better value?
No. Discounts, coupons and shrinkflation regularly reverse the usual pattern: a promotion can make the small pack cheaper per unit, and a bigger pack can work out dearer if its size grew less than its price. Compare the unit prices rather than assuming — and only buy the larger size if you’ll actually finish it.
Can I compare grams with millilitres?
Not without the product’s density, which labels don’t print. Treating a gram as a millilitre is about 9% wrong for cooking oil and roughly 30% wrong for honey — bigger than most savings you’re chasing. The calculator ranks only products measured the same way and tells you plainly when a comparison isn’t possible.
What’s the difference between US and UK fluid ounces?
A US fluid ounce is 29.57 ml; a UK (imperial) fluid ounce is 28.41 ml — about 4% apart under the same name. Pints and gallons differ far more: a US pint is 473 ml, an imperial pint 568 ml. The calculator keeps both systems labelled and separate.
How do multipacks work in the calculation?
Enter the number of packs and the size of one pack. A 4 × 250 g multipack is treated as 1,000 g and compared on that total — the same maths a cashier’s system should do.
Which currency does the calculator use?
Yours. Pick any of the 150+ supported currencies from the currency box and its symbol appears next to every result. No conversion ever happens: enter prices in one currency per comparison.
Do I need an account? Where are my saved comparisons kept?
No account, ever. Saved comparisons live in your browser’s local storage only, and share links encode everything in the URL. Nothing is uploaded.
Why do stores show different unit prices on their shelf labels?
Each retailer picks its own standard unit — per 100 g, per kilo, per litre — and promotion labels sometimes leave the unit price off entirely. That inconsistency is why comparing on your own, in one standard unit, beats reading the shelf edge.
Ready to try it? Open the unit price calculator — it works on a phone in the aisle, with no login and no ads.