Milliliters to Ounces: Convert mL to oz and fl oz
Before converting anything, one question decides the answer: do you want fluid ounces or weight ounces? They share a name and measure entirely different things, and picking the wrong one is the single most common error in this conversion.
- Fluid ounces (fl oz) measure volume, like milliliters. Use these for recipes, drinks and bottle labels.
- Weight ounces (oz) measure weight, like grams. Use these when something goes on a scale or a shipping label.
Converting to fluid ounces is fixed arithmetic. Converting to weight ounces depends on what the liquid is, and that same density figure is what turns milliliters into kilograms once a batch outgrows ounces.
Milliliters to Fluid Ounces
There are two fluid ounces in use, and they are not the same size. The US fluid ounce is 29.5735 mL. The imperial fluid ounce, used in the UK, is 28.4131 mL, about 4 percent smaller.
US fluid ounces = milliliters / 29.5735
UK fluid ounces = milliliters / 28.4131
| Milliliters | US fl oz | UK fl oz |
|---|---|---|
| 5 mL | 0.17 | 0.18 |
| 15 mL | 0.51 | 0.53 |
| 30 mL | 1.01 | 1.06 |
| 50 mL | 1.69 | 1.76 |
| 100 mL | 3.38 | 3.52 |
| 200 mL | 6.76 | 7.04 |
| 250 mL | 8.45 | 8.80 |
| 330 mL | 11.16 | 11.61 |
| 500 mL | 16.91 | 17.60 |
| 750 mL | 25.36 | 26.40 |
| 1,000 mL | 33.81 | 35.20 |
For a quick mental estimate, 30 mL is roughly one fluid ounce either way. That approximation is close enough for a cocktail and too loose for a pharmacy.
Milliliters to Weight Ounces
Here the liquid matters, because the question is how heavy it is. One weight ounce is 28.3495 grams:
weight ounces = milliliters x density (g/mL) / 28.3495
| Milliliters | Water | Milk | Vegetable Oil | Honey |
|---|---|---|---|---|
| 50 mL | 1.76 oz | 1.82 oz | 1.62 oz | 2.50 oz |
| 100 mL | 3.53 oz | 3.63 oz | 3.25 oz | 5.01 oz |
| 250 mL | 8.82 oz | 9.08 oz | 8.11 oz | 12.52 oz |
| 500 mL | 17.64 oz | 18.17 oz | 16.23 oz | 25.04 oz |
| 750 mL | 26.46 oz | 27.25 oz | 24.34 oz | 37.57 oz |
| 1,000 mL | 35.27 oz | 36.33 oz | 32.45 oz | 50.09 oz |
Spotting Which One a Label Means
A drinks can, a bottle of shampoo or a carton of juice states its contents in fluid ounces, usually written fl oz, alongside the milliliters. A bag of coffee beans, a block of cheese or a parcel weight is in weight ounces, written oz. Once a parcel passes a pound, courier software drops ounces and quotes the weight in pounds instead.
A telling example: a 355 mL can of soda is labeled 12 fl oz, but the liquid inside weighs about 12.5 weight ounces, a little more if it is a full-sugar drink, and the can with it weighs more still. Same number on the front, different meaning.
Why the US and UK Ounces Differ
The two systems defined their fluid ounce from different starting points. The imperial fluid ounce was set so that ten of them held ten ounces of water by weight, tying volume neatly to weight. The US fluid ounce descends from an older English wine gallon and kept a slightly different size.
The gap runs through everything built on them: a US pint is 473 mL against the imperial 568 mL, and a US gallon is 3,785 mL against 4,546 mL. On a single recipe the difference is minor, but scaled up it becomes obvious, which is why British and American recipe books can produce noticeably different results from the same instructions.
Common Questions
How many mL in an ounce?
A US fluid ounce is 29.5735 mL and a UK fluid ounce is 28.4131 mL. A weight ounce has no fixed volume at all, since it depends on the liquid: one ounce of water fills 28.35 mL, while an ounce of honey takes only 20 mL. Fluid ounces convert directly, weight ounces do not.
Is 250 mL the same as 8 oz?
Close, but not exact. 250 mL is 8.45 US fluid ounces, and an 8 fl oz cup is 236.6 mL. Recipes often round 250 mL to a cup, which adds about 5 percent. For most cooking that is harmless; for baking, where ratios matter, it is worth using the precise figure.
Which ounce should I use for a recipe?
Follow where the recipe came from. American recipes mean US fluid ounces for liquids and weight ounces for solids, while British recipes that use ounces mean imperial fluid ounces for liquids. If the recipe lists both grams and milliliters, use those instead and skip the ounce conversion entirely; the liters to grams calculator will take you the rest of the way.
How many mL in a shot?
A US shot is generally 1.5 fl oz, which is 44 mL, although no federal standard defines it. A UK single measure is set by law at 25 mL or 35 mL depending on the venue, and a double is twice that. Bar recipes from different countries therefore pour noticeably different drinks from identical instructions.