fl oz and oz: two different units
Fluid ounces and ounces share the word “ounce” but measure completely different things. This page is for fluid ounces (volume). For mass ounces, see the ounces to grams page.
The numerical values differ too: 1 fl oz (volume) = 29.57 ml, while 1 oz (mass) = 28.35 g. These are different quantities in different units — they cannot be directly compared or converted without knowing the density of the substance in question.
What is a fluid ounce?
A fluid ounce (fl oz) is a unit of volume, not mass. It measures how much space a liquid occupies. Two versions exist:
| System | 1 fl oz = | Defined as |
|---|---|---|
| US fluid ounce | 29.5735 ml | 1/128 US gallon |
| Imperial fluid ounce | 28.4131 ml | 1/160 Imperial gallon |
8 US fl oz = 1 US cup = 236.588 ml. This is the foundation of US liquid measurement in cooking.
Abbreviation
Always written as “fl oz” to distinguish it from the avoirdupois ounce (oz). On US nutrition labels you may see “fl oz” or “floz”.
US vs Imperial fluid ounce
The US fluid ounce (29.57 ml) is about 4% larger than the Imperial fluid ounce (28.41 ml). For small amounts the difference is minor, but for large volumes (e.g. 32 fl oz) it amounts to over 37 ml.
US vs Imperial fluid ounces
| Amount | US fl oz (ml) | Imperial fl oz (ml) | Difference |
|---|---|---|---|
| 1 fl oz | 29.57 ml | 28.41 ml | 1.16 ml |
| 4 fl oz | 118.29 ml | 113.65 ml | 4.64 ml |
| 8 fl oz | 236.59 ml | 227.30 ml | 9.29 ml |
| 16 fl oz | 473.18 ml | 454.61 ml | 18.57 ml |
| 20 fl oz | 591.47 ml | 568.26 ml | 23.21 ml |
| 32 fl oz | 946.35 ml | 909.22 ml | 37.13 ml |
Fluid ounces to ml reference table (US)
| Fluid ounces | ml (US) | Cup equivalent |
|---|---|---|
| ½ fl oz | 14.8 ml | |
| 1 fl oz | 29.6 ml | |
| 1½ fl oz | 44.4 ml | |
| 2 fl oz | 59.1 ml | ⅛ cup |
| 3 fl oz | 88.7 ml | |
| 4 fl oz | 118.3 ml | ½ cup |
| 5 fl oz | 147.9 ml | |
| 6 fl oz | 177.4 ml | |
| 7 fl oz | 207 ml | |
| 8 fl oz | 236.6 ml | 1 cup |
| 10 fl oz | 295.7 ml | |
| 12 fl oz | 354.9 ml | |
| 14 fl oz | 414 ml | |
| 16 fl oz | 473.2 ml | 2 cups |
| 20 fl oz | 591.5 ml | |
| 24 fl oz | 709.8 ml | |
| 32 fl oz | 946.4 ml | 4 cups |
| 64 fl oz | 1892.7 ml | 8 cups |
| 128 fl oz | 3785.4 ml | 1 gallon |
Fluid ounces and US cups
The US cup is defined as exactly 8 US fluid ounces = 236.588 ml. All fractional cup measurements follow from this.
| Cups | fl oz | ml |
|---|---|---|
| ¼ cup | 2 fl oz | 59.1 ml |
| ⅓ cup | 2.67 fl oz | 78.9 ml |
| ½ cup | 4 fl oz | 118.3 ml |
| ⅔ cup | 5.33 fl oz | 157.7 ml |
| ¾ cup | 6 fl oz | 177.4 ml |
| 1 cup | 8 fl oz | 236.6 ml |
Common container sizes
| Container | fl oz | ml |
|---|---|---|
| Shot glass | 1.5 fl oz | 44 ml |
| Small juice glass | 4 fl oz | 118 ml |
| Standard soda can (US) | 12 fl oz | 355 ml |
| Standard beer bottle | 12 fl oz | 355 ml |
| US pint | 16 fl oz | 473 ml |
| UK/Imperial pint | 20 fl oz | 568 ml |
| Wine bottle | ~25.4 fl oz | 750 ml |
| 1-litre bottle | ~33.8 fl oz | 1000 ml |
| US quart | 32 fl oz | 946 ml |
| 2-litre bottle | ~67.6 fl oz | 2000 ml |
| US gallon | 128 fl oz | 3785 ml |
Frequently asked questions
How many ml is 1 fluid ounce?
1 US fluid ounce = 29.5735 ml exactly. 1 Imperial (UK) fluid ounce = 28.4131 ml. The US fluid ounce is the more commonly referenced value in international recipes and product labelling.
How many fluid ounces is 1 cup?
1 US cup = 8 US fluid ounces = 236.588 ml (commonly rounded to 236.6 ml). This is one of the most important kitchen measurement relationships. The US cup is defined as exactly 8 US fl oz.
What is the difference between US and Imperial fluid ounces?
1 US fl oz = 29.5735 ml. 1 Imperial (UK) fl oz = 28.4131 ml. The difference is 1.16 ml per fl oz, or about 4%. Over larger amounts this adds up: 20 fl oz differs by 23.2 ml between the two systems.
How many ml is 8 fluid ounces?
8 US fluid ounces = 236.6 ml (8 × 29.5735 = 236.588 ml). This equals exactly 1 US cup. It is one of the most important kitchen conversions: a standard US measuring cup holds 8 fl oz = 236.6 ml.
What is the difference between fl oz and oz?
fl oz (fluid ounce) is a unit of volume: 1 US fl oz = 29.5735 ml. oz (ounce, avoirdupois) is a unit of mass: 1 oz = 28.3495 g. They measure completely different physical properties. You cannot convert between them without knowing the density of the substance.
How many fluid ounces is 250 ml?
250 ml ÷ 29.5735 = 8.454 US fl oz. This is approximately 8.45 US fl oz, which is just over 1 US cup (8 fl oz). 250 ml is also called a “metric cup” in Australia and some other countries.
How many fluid ounces in 1 litre?
1 litre = 1000 ml. 1000 ÷ 29.5735 = 33.814 US fl oz. Or in Imperial: 1000 ÷ 28.4131 = 35.195 Imperial fl oz. A standard 1-litre water bottle contains approximately 33.8 US fl oz.
Is 12 fl oz a standard can size?
Yes. 12 US fl oz = 354.9 ml (12 × 29.5735). This is the standard size for US soda cans and beer cans. In the EU, the standard can is 330 ml (≈ 11.16 fl oz), slightly smaller.