OZ to ML Converter
Enter fluid ounces, get millilitres live. Free, no sign-up, works offline once loaded.
Need the opposite? ML to OZ
This oz to ml converter is for decoding American volumes into metric. The formula: ml = fl oz × 29.5735. Each US fluid ounce is a shade under 30 ml, so ounce figures roughly multiply by 30 when they cross the Atlantic.
US recipes are the big driver. "8 oz of water" — the classic American cup — is 236.6 ml, so fill your metric jug to just under 240. A 12 oz can of soda is 354.9 ml, slightly more than the metric 330 ml can. Behind the bar, the standard US 1.5 oz shot is 44.4 ml, and a 5 oz glass of wine is 147.9 ml.
Airport security is the other one: the famous 3.4 oz carry-on liquid limit is exactly the 100 ml rule, converted. The tool runs fully in your browser — free, instant and private.
How to convert oz to ml
- Type the fluid-ounce value (decimals like 3.4 work fine).
- The millilitre result appears instantly below the input.
- Adjust the ounces to work through a whole recipe.
- Tap the swap control to convert ml to oz instead.
- Copy the ml figure for your shopping list or notes.
American ounces you will actually meet
In the kitchen: 1 fl oz = 29.6 ml, 2 fl oz = 59.1 ml, 4 fl oz (half a cup) = 118.3 ml, 8 fl oz (one cup) = 236.6 ml, 16 fl oz (one US pint) = 473.2 ml, 32 fl oz (one quart) = 946.4 ml. If a recipe says "one cup", metric cooks can safely use 240 ml.
Travel and toiletries: the TSA and EU carry-on limit of 3.4 fl oz equals 100.6 ml, which is why travel-size bottles are sold at exactly 100 ml. A 1 oz espresso shot is 29.6 ml, a 16 oz "grande" coffee is 473 ml, and the giant 40 oz insulated tumbler trend holds 1.18 litres.
The exact factor behind ×29.5735
One US fluid ounce is defined as exactly 29.5735 millilitres, so the formula is simply ml = fl oz × 29.5735. The odd-looking number comes from the US gallon being split into 128 fluid ounces, a division that never matched the metric litre and so leaves this awkward multiplier.
The tool uses the US fluid ounce because that is what American recipes, cans and bottles mean. The UK imperial fluid ounce is a slightly smaller 28.4131 ml, so a genuinely British measurement should use that figure — a distinction that mostly surfaces in older UK cookbooks.
A worked example, step by step
Convert a 12 oz can of soda. Apply ml = fl oz × 29.5735: 12 × 29.5735 = 354.9 ml. That is why a US 12 oz can holds a little more than the 330 ml can common in Europe — about 25 ml more, or nearly a mouthful.
Reverse it to confirm: 354.9 ÷ 29.5735 = 12.0 fl oz, back to the start. The reverse divide is the fastest way to catch the common error of dividing by 29.57 when you should multiply, which would shrink a drink to a fraction of a millilitre.
A quick-reference set of common ounces
Useful anchors: 1 fl oz = 29.6 ml, 1.5 fl oz = 44.4 ml (a US spirit shot), 3.4 fl oz = 100 ml (the carry-on limit), 5 fl oz = 147.9 ml (a wine pour), 8 fl oz = 236.6 ml (a US cup), 12 fl oz = 354.9 ml (a soda can). The mental hook is that 1 oz is almost exactly 30 ml.
Larger sizes appear in coffee culture: a 16 oz 'grande' is 473 ml, a 20 oz 'venti' is 591 ml, and the 40 oz tumbler trend holds 1,183 ml — well over a litre. Because the factor is constant you can add: a 24 oz drink is simply 16 oz (473) plus 8 oz (237), about 710 ml.
Why American volumes come in ounces
The United States kept the customary system for everyday life, so drinks, recipes and container labels are sized in fluid ounces even though science and medicine there run on millilitres. Reading a US recipe, a nutrition panel or a bar menu therefore means converting ounces to metric to picture the real amount.
The habit spills into products sold worldwide: American-designed bottles, coffee-chain cup sizes and canned drinks carry ounce figures on the label. Travel is the sharpest case — the carry-on liquid rule is written as 100 ml in metric countries but printed as 3.4 fl oz on US-market travel bottles, the same limit in two units.
How precise should the millilitres be?
For cooking and drinks, rounding to whole millilitres is plenty: 5 oz of wine as 148 ml pours identically to 147.9. The multiply-by-30 shortcut overshoots by about 1.4%, harmless for a glass of water but worth avoiding when a dose or a strict volume limit is involved, where the exact 29.5735 factor should be used.
Remember too that fluid ounces measure volume, not weight. The tool converts how much space a liquid fills; it cannot tell you the mass, because that depends on the liquid's density. Only for water does 1 fl oz happen to weigh close to 1 ounce, so do not use it to convert a recipe's weight of flour or sugar.
The reverse: millilitres back to ounces
To undo the conversion, divide millilitres by 29.5735 — the inverse of the multiply, so converting and converting back returns your original ounces exactly. The swap control switches the tool to ml to oz in a single tap.
A built-in sanity check: because a fluid ounce is far bigger than a millilitre, the millilitre figure is always the larger number for the same liquid. If your millilitre answer came out smaller than the ounces you typed, the operation was inverted — multiply by 29.5735, do not divide.
Frequently asked questions
What is the oz to ml formula?
Multiply US fluid ounces by 29.5735. So 8 fl oz × 29.5735 = 236.6 ml. For imperial (UK) fluid ounces the factor is 28.4131 instead.
What is the fastest mental estimate?
Multiply by 30. For 6 oz: 6 × 30 = 180 ml (exact answer 177.4). The shortcut runs about 1.4% high — trim a spoonful off for anything precise.
Why is the airport liquid limit 3.4 oz?
Because the rule was written as 100 ml and 3.4 fl oz is its US translation (3.4 × 29.5735 = 100.55 ml). Bottles labelled 3.4 oz and 100 ml are the same product.
How many ml is a US cup?
A US cup is 8 fl oz, which is 236.6 ml. Metric recipes usually treat a cup as 240 ml, and the 1.4% difference is invisible in cooking.
Is a fluid ounce the same as an ounce of weight?
No. A fluid ounce measures volume; the ounce on a kitchen scale measures weight (28.35 g). They only coincide for water-like liquids, where 1 fl oz of water weighs roughly 1 oz. This tool converts volume.
Is this converter free, and is my input private?
Yes. It is free with no account, and the calculation runs locally in JavaScript — nothing you type leaves your device.