Everyday Money
Cost Per 100ml Calculator
Enter pack price and volume to see cost per 100ml, per litre and per ml.
Compare liquids fairly
Liquid products rarely share the same bottle size, so the shelf price alone is a poor guide. Normalising to cost per 100ml (or per litre) shows which offer is genuinely cheaper before you fill the trolley. This helps with shampoo, detergent, soft drinks, cooking oil, paint samples and any other fluid sold by volume. Enter the pack price and the millilitres on the label; the calculator scales to 100ml so different formats sit on one scale. Concentrate products need care: a small bottle that dilutes may beat a large ready-to-use jug even when per-100ml looks dearer. For solids by weight, use the cost per 100g calculator; for mixed units side by side, try unit price comparison. Quality, scent and waste are not priced here — only the arithmetic of volume. Online grocery labels sometimes quote per litre while the shelf sticker quotes per 100ml — convert before you decide. Multipack bottles need total millilitres across the wrap, not the single-bottle figure printed in small type.
Worked example
A 750ml shampoo at £6.00 is £0.80 per 100ml. A 400ml rival at £3.60 is £0.90 per 100ml. The larger bottle wins on unit price if you will finish it. If the small one is a brand you use more slowly and the large one expires unused, the cheaper pack can still waste money.
Limits and assumptions
Labels must use the same basis (ml of product, not diluted wash water). Promotions that require loyalty cards or multibuy rules are not modelled — enter the price you will actually pay. Shipping on online orders can reverse an in-store unit-price win. Loyalty prices and ‘was/now’ stickers should use the price you will pay at the till.
Frequently asked questions
Why compare liquids per 100ml?
Pack sizes differ. Per 100ml puts every bottle on the same footing so the cheaper unit price is obvious.
Should I convert to cost per litre instead?
Either works. Per 100ml suits small bottles; per litre suits large containers. Multiply per 100ml by 10 for per litre.
How do concentrates compare?
Work out the ready-to-use volume after dilution, then price that volume — not the concentrate bottle alone.
Does this include refill pouches?
Yes if you enter pouch price and millilitres. Refills often win on unit price and packaging waste.
What about buy-one-get-one offers?
Use the effective price after the deal (total spend ÷ total ml). Stacked discounts are easier with the discount stacking calculator.