--- title: "Unit Price Calculator: per 100 g, kg, oz & lb | Pebble Pouch" description: "Work out the unit price of anything on the shelf: per 100 g, kg, oz or lb, per litre or fluid ounce, or per item, with metric and US units converted." url: https://pebblepouch.shop/ --- # Unit price calculator Is the big jar really the better deal? Type the price and the size and see what you pay per 100 g, per kilo, per ounce or per pound, whatever unit the label uses. ## How a unit price is worked out A unit price is the shelf price divided by how much is in the pack, scaled up to a round amount so that different pack sizes can be compared fairly. The calculator turns the pack into grams, millilitres or items first, then shows the price per 100 g, per kg, per ounce and per pound, or per 100 ml, litre, US fluid ounce and US gallon for liquids. Unit price = price ÷ (packs × size of each) × the amount you want it per Example: £2.50 for 500 g is 2.50 ÷ 500 = £0.005 a gram, so £0.50 per 100 g and £5.00 per kg. For a multipack, enter the number of packs and the size of one: 6 × 330 ml cans for £4.50 hold 1,980 ml, which is £2.27 per litre. ### Why the shelf label isn't always enough Many shops print a unit price, but not always in the same unit: one label says per 100 g, the next per kg, and imported goods may be priced per ounce or per pound. Putting everything into the same unit is the only fair comparison. ## Sources - NIST, [Guide to the SI, Appendix B.9](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9): conversion factors for the ounce, pound, US fluid ounce, US gallon and the UK (imperial) gallon and fluid ounce. - [The Price Marking Order 2004](https://www.legislation.gov.uk/uksi/2004/102/contents) (UK), article 5: the obligation for traders to show a unit price. - NIST Handbook 130, [Uniform Unit Pricing Regulation](https://www.nist.gov/document/2026-hb-130-section-iv-c): the model unit pricing rules US states can adopt. ## More ways to find the better buy Every tool works in your browser, with metric and US units. - [Compare unit prices](https://pebblepouch.shop/compare-unit-prices/): Line up several products in mixed units and rank them from best value to dearest. - [Bulk vs small pack](https://pebblepouch.shop/bulk-vs-small-pack/): Is the big pack still cheaper once you count what goes off before you finish it? - [Price per use](https://pebblepouch.shop/price-per-use/): Cost per wear or per use, so a sturdier buy can be weighed against a cheaper one. - [Shrinkflation checker](https://pebblepouch.shop/shrinkflation-checker/): The old pack against the new one: how much more you really pay per gram or millilitre. ## Recommended Two free services for the online side of shopping. Disposable email · no sign-up ### CleanTempMail Loyalty schemes, coupon sites and "sign up for 10% off" boxes all want an email address. CleanTempMail gives you a free temporary inbox straight away, with no sign-up, a random or custom address on hundreds of domains, and messages deleted automatically after 3 days. Collect the code and keep the marketing out of your real inbox. [Open a temporary inbox](https://cleantempmail.com/) Disposable cloud browser · domain lookups ### WebTraceCheck Spotted a bargain in an online shop you have never heard of? WebTraceCheck's free DNS and domain lookup shows the records behind the shop's domain, and its disposable cloud browser opens the site on an isolated desktop that is deleted after each session. Nothing to install, with free time every day. [Check a shop with WebTraceCheck](https://webtracecheck.com/) ## Questions **Should I compare per 100 g or per kg?** Either, as long as both products use the same one. They are the same number with the decimal point moved, because a kilo is ten lots of 100 g. If one label shows £0.65 per 100 g and another £6.20 per kg, multiply the first by ten (£6.50 per kg) before you compare. **What is the difference between ounces and fluid ounces?** An ounce (oz) is a weight of about 28.35 g. A fluid ounce is a volume: about 29.57 ml in the US and 28.41 ml in the UK. Use ounces for solids such as cereal or coffee, and fluid ounces for drinks, sauces and shampoo. **Can I compare something sold by weight with something sold by volume?** Not directly. A litre of honey weighs much more than a litre of milk, so grams and millilitres only line up if you know the density, which labels rarely give. Compare products sold the same way. **Is anything I type saved?** Only the currency you pick, in your browser's local storage on this device, so the other tools use it too. Prices and sizes are never sent anywhere.