How many millilitres are in a fluid ounce?

One US fluid ounce equals exactly 29.5735295625 millilitres. One Imperial (UK) fluid ounce equals exactly 28.4130625 millilitres. The US fluid ounce is more commonly used in recipes and product labels internationally, so unless a recipe specifies Imperial, assume US fluid ounces.

How do I convert ounces to millilitres?

Multiply the number of fluid ounces by 29.5735 (for US fl oz) or by 28.4131 (for Imperial fl oz). For example, 8 US fl oz multiplied by 29.5735 equals 236.59 mL, which is a standard US cup. For a quick mental estimate, multiply by 30: 8 fl oz is approximately 240 mL.

Is an ounce of liquid the same as an ounce of weight?

No. A fluid ounce (fl oz) is a unit of volume, not weight. A weight ounce (oz) measures mass. One weight ounce equals 28.3495 grams. One US fluid ounce equals 29.5735 mL. For water specifically, 1 US fl oz of water weighs approximately 29.57 grams, because water has a density close to 1 g/mL. For other liquids such as oil or honey, the weight per fluid ounce will differ.

Ounces to Millilitres Converter

This converter turns fluid ounces (fl oz) into millilitres (mL), and back again, so you know exactly how much liquid a recipe, supplement label or imported product is really asking for. New Zealand measures volume in millilitres and litres, so converting matters whenever you meet a measurement in fluid ounces. You choose whether you are working with a US fluid ounce (29.5735 mL) or an Imperial fluid ounce (28.4131 mL), because the two differ by about 4 percent and using the wrong one will throw off a recipe or dosage. Enter a fluid ounce figure directly, pick from common quantities such as a single shot, a US cup, a pint or a gallon, or use the swap button to enter millilitres instead and convert back to fluid ounces. The results bar then shows your amount in fluid ounces, the millilitre equivalent, and the same volume again in litres, all updating instantly as you type or change the ounce type. Underneath, a reference table lists common quantities in both US and Imperial millilitres side by side, so you can compare the two systems at a glance. As a rule, use the US fluid ounce setting for modern recipes and American product labels, and switch to Imperial only for older British or Commonwealth measurements, since assuming the wrong standard is the most common mistake made with this conversion.

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Exact conversion factors US fl oz: 29.5735295625 mL exactly. Imperial fl oz: 28.4130625 mL exactly. NIST Handbook 44.

1. Conversion Type

Fluid ounce type

Common quantities (optional shortcut)

2. Enter Value

Fluid ounces (fl oz)

fl oz

Conversion Result

Fluid Ounces

8.00

US fl oz

Millilitres
236.59
mL

Litres

0.2366

Common Conversions Reference Table

Fluid Ounces (fl oz)	Millilitres (mL) US	Millilitres (mL) Imperial	Common name

How to Convert Fluid Ounces to Millilitres

The conversion from fluid ounces to millilitres depends on whether you are using the US fluid ounce or the Imperial (UK) fluid ounce. The two are different units, so it matters which system the recipe or label uses.

US fluid ounce: 1 fl oz = 29.5735295625 mL (exactly, by definition)
Imperial fluid ounce: 1 fl oz = 28.4130625 mL (exactly, by definition)

To convert, multiply the number of fluid ounces by the relevant factor:

mL = fl oz x 29.5735 (US) or mL = fl oz x 28.4131 (Imperial)

To convert back from millilitres to fluid ounces, divide by the same factor:

fl oz = mL / 29.5735 (US) or fl oz = mL / 28.4131 (Imperial)

Worked Example

Default inputs: 8 US fl oz

mL = 8 x 29.5735295625 = 236.59 mL
Litres = 236.59 / 1000 = 0.2366 L

This is exactly 1 US cup (which is defined as 8 US fl oz = 236.588 mL). Handy to remember when scaling recipes.

US vs Imperial Fluid Ounces

The US fluid ounce and the Imperial fluid ounce are similar but not identical. The US fluid ounce is approximately 4.1% larger than the Imperial fluid ounce. This small difference matters when precision is important, such as in pharmaceutical dosing or scientific work.

Quantity	US fl oz equivalent	Imperial fl oz equivalent
1 cup (US)	8 fl oz = 236.59 mL	8 fl oz = 227.30 mL
1 pint (US)	16 fl oz = 473.18 mL	20 fl oz = 568.26 mL
1 quart (US)	32 fl oz = 946.35 mL	40 fl oz = 1136.52 mL
1 gallon (US)	128 fl oz = 3785.41 mL	160 fl oz = 4546.09 mL

When Does It Matter?

Most printed recipes from the United States and international product labels use US fluid ounces. UK and older Commonwealth recipes may use Imperial fluid ounces. In New Zealand, volumes are typically given in millilitres or litres, so this converter is useful when following recipes from American websites or measuring liquid ingredients in US-labelled measuring tools.

Quick Reference: Fluid Ounces in Millilitres

1 fl oz (US) = 29.57 mL
2 fl oz (US) = 59.15 mL
4 fl oz (US) = 118.29 mL (half a US cup)
8 fl oz (US) = 236.59 mL (1 US cup)
12 fl oz (US) = 354.88 mL (standard can of drink)
16 fl oz (US) = 473.18 mL (US pint)
32 fl oz (US) = 946.35 mL (US quart)
128 fl oz (US) = 3,785.41 mL (US gallon)

Related Converters

Sources: National Institute of Standards and Technology (NIST) Handbook 44, Appendix C: General Tables of Units of Measurement. International Bureau of Weights and Measures (BIPM): The International System of Units (SI).

This converter uses the exact defined values for US and Imperial fluid ounces. For cooking purposes, rounding to 1 or 2 decimal places is sufficient. For pharmaceutical or scientific use, apply the full precision factors given above.