How Many mL Are in an Ounce?
Quick Answer: 29.57 mL in 1 US fluid ounce · 30 mL (kitchen rounding) · 28.41 mL (Imperial/UK)
At a glance
- 1 US fluid ounce = 29.5735 mL (the exact US conversion — use this for medicine, cocktails, anything precise)
- Kitchen shortcut: 30 mL per fl oz (easier to remember; within 1.5% — fine for cooking)
- Imperial (UK) fluid ounce = 28.41 mL (smaller than US; appears on some older British recipes and pub measures)
A US fluid ounce holds exactly 29.5735 millilitres, which most people round to 30 mL for everyday use. The shortcut is close enough for cooking (you\'re off by less than 2%), but medical dosing, bar recipes, and lab work use the precise figure. The two numbers you\'ll run into most often are 30 (rounded cooking conversion) and 29.57 (printed on measuring tools). Both are correct — context tells you which to pick.
What does 1 fl oz look like next to 30 mL?
fl oz → mL Quick Converter
Need more features? Try our complete fluid ounce to millilitre converter.
1 fluid ounce on the millilitre scale
1 fl oz = 29.57 mL (almost exactly 30)
29.57, 30, or 28.41 — which mL number do I actually use?
Three different "mL per ounce" numbers show up in everyday life, and each one is correct in its own context:
- 29.5735 mL — the exact US fluid ounce. Use this for medicine dosing, cocktail recipes, chemistry, and anywhere proportions matter at small volumes.
- 30 mL — the kitchen shortcut. Within 1.5% of the real value; fine for cooking, baking, drink mixing at home. Printed on many measuring jugs and beakers.
- 28.4131 mL — the Imperial (UK) fluid ounce. The Imperial gallon is larger than the US gallon, but the Imperial fluid ounce is smaller than the US one — because each country divided its gallon into 160 or 128 parts respectively. Matters for older British cookbooks.
The 29.57 vs 30 gap is a rounding convention, not a competing standard — everyone agrees on 29.5735 as the definition. The 28.41 figure is a different system entirely. If a recipe came from the US, use 29.57; if from the UK before the switch to litres (pre-1970s mostly), assume 28.41. Modern UK recipes use mL directly and skip the issue.
How many ounces in 750 mL, 500 mL, and other bottle sizes?
Most "how many ounces in X mL" searches come from labels on bottles — wine, spirits, water, soda, medicine. Here\'s the conversion for every common container size, with the real-world product attached.
| Volume (mL) | US fluid ounces | Typical product |
|---|---|---|
| 50 mL | 1.69 fl oz | Airplane-size "mini" liquor bottle; small perfume |
| 100 mL | 3.38 fl oz | TSA carry-on liquid limit (3.4 oz matches this); skincare |
| 200 mL | 6.76 fl oz | Small juice box; half-pint liquor "hip flask" size |
| 250 mL | 8.45 fl oz | Standard coffee mug; metric "cup"; small water bottle |
| 330 mL | 11.16 fl oz | European soda/beer can |
| 355 mL | 12 fl oz | US standard soda can (labelled "12 fl oz", actually 355 mL) |
| 375 mL | 12.68 fl oz | "Half bottle" of wine; pint-size spirits bottle |
| 500 mL | 16.91 fl oz | Standard single-serve water bottle globally |
| 750 mL | 25.36 fl oz | Standard wine bottle; standard liquor "fifth" |
| 1,000 mL (1 L) | 33.81 fl oz | 1 litre water, juice, spirits bottle |
| 1,500 mL (magnum) | 50.72 fl oz | Magnum wine bottle (2 standard bottles) |
| 1,750 mL (handle) | 59.18 fl oz | Half-gallon spirits "handle" bottle |
These numbers use the US fluid ounce (29.5735 mL). For Imperial (UK) ounces, divide by 28.41 instead of 29.57 — the ounce count will be about 4% higher.
Did you know?
The US and UK fluid ounces diverged on the same day: 5 January 1824, when the UK Parliament passed the Weights and Measures Act and redefined the Imperial gallon as exactly 10 pounds of distilled water. That created a new, larger gallon (4.546 L vs the older 3.785 L the US had inherited), but it was divided into 160 Imperial fl oz instead of 128. The US kept the older definition. Today the US fl oz (29.57 mL) and Imperial fl oz (28.41 mL) differ by about 4%, but both trace back to the same medieval English unit — a wine gallon from 1707.
How many ounces are in a millilitre?
0.0338 fl oz per mL — basically, divide mL by about 30 to get ounces. The mL is far smaller than the fl oz, so this direction is rarely asked for single mL amounts; it shows up in the chunkier form "how many ounces in 100 mL" or "500 mL", which the table above covers.
- 1 mL = 0.0338 fl oz (≈ 1/30 fl oz)
- 5 mL = 0.17 fl oz (a standard US teaspoon)
- 15 mL = 0.51 fl oz (a standard US tablespoon)
- 30 mL = 1.01 fl oz (about one fluid ounce — that\'s the kitchen shortcut)
Common ounce-to-millilitre amounts
Values shown are NIST-exact conversions rounded to 2 decimals. For cooking use, most recipes treat 1 fl oz as ≈ 30 mL.
| Fluid ounces | Millilitres (US) | Millilitres (UK/Imperial) |
|---|---|---|
| ¼ fl oz | 7.39 mL | 7.10 mL |
| ½ fl oz | 14.79 mL | 14.21 mL |
| 1 fl oz | 29.57 mL | 28.41 mL |
| 1.5 fl oz (US shot) | 44.36 mL | 42.62 mL |
| 2 fl oz | 59.15 mL | 56.83 mL |
| 4 fl oz (½ cup) | 118.29 mL | 113.65 mL |
| 6 fl oz | 177.44 mL | 170.48 mL |
| 8 fl oz (1 cup) | 236.59 mL | 227.30 mL |
| 12 fl oz (soda can) | 354.88 mL | 340.96 mL |
| 16 fl oz (1 US pint) | 473.18 mL | 454.61 mL |
| 32 fl oz (1 quart) | 946.35 mL | 909.22 mL |
Word order matters (and ounce vs fluid ounce too)
- "How many mL in an ounce?" → 29.57 mL (fluid ounce implied — the volume question)
- "How many mL in an ounce (weight)?" → depends on density. 1 oz of water ≈ 29.57 mL; 1 oz of honey ≈ 21 mL; 1 oz of oil ≈ 32 mL. Volume and weight only match for water.
- "How many ounces in a mL?" → 0.0338 fl oz (the reverse)
The formula
mL = fl oz × 29.5735 (US)
mL = fl oz × 28.4131 (Imperial / UK)
The US fluid ounce is defined as exactly 1/128 of a US gallon, and the US gallon is defined as exactly 3.785411784 litres — so 1 US fl oz is 29.5735295625 mL by definition. The Imperial fluid ounce comes from a different gallon (4.54609 L / 160 = 28.4130625 mL). Both are exact by convention, not by measurement; the decimal expansion just looks messy because the systems were defined centuries apart.
For quick mental math in either direction: multiply fluid ounces by 30 to get mL, or divide mL by 30 to get fluid ounces. The error is small enough that you won\'t notice it in cooking or casual drink mixing. For anything where a 1-2% error matters — medicine, precise baking, or classic cocktails built on small pours — use the exact 29.5735 factor instead.
How to measure between ounces and millilitres
With a graduated measuring cup
Most US kitchen measuring cups are dual-labelled — one side shows fluid ounces, the other millilitres. The two scales line up using the 30-mL-per-ounce rounding, so 8 fl oz on the cup marks 240 mL, not 236.59. The 4% rounding is absorbed into the marking. For recipe scaling this is fine; for anything precise, measure by the number that matches your recipe\'s system.
With a medicine dropper or oral syringe
Medicine is almost always dosed in mL in the US, even when the label says "teaspoon" or "fl oz". A medicine dropper typically has mL markings to 0.1 or 0.25 mL precision. Don\'t convert "1 teaspoon = 5 mL" by eye — use the labelled markings directly.
With a shot glass or jigger
A US standard shot is 1.5 fl oz (44 mL). If a cocktail recipe gives amounts in mL (common for European cocktail books), a 1:1 substitution works if you trust the 30-mL-per-ounce rounding. For classic cocktails where proportions really matter — martinis, negronis, daiquiris — use an exact jigger or scale, not rounded conversions.
Frequently Asked Questions
How many mL are in an ounce?
29.57 mL per US fluid ounce (rounded to 30 mL in most kitchens). The exact value is 29.5735 mL — the rounding to 30 is close enough for cooking, but medicine and lab work use the precise figure.
How many ounces are in 750 mL?
About 25.36 US fluid ounces, or almost exactly 25.4 fl oz. A 750 mL bottle is the standard wine and spirits bottle size in the US, and it holds a little over a pint and a half. In Imperial (UK) ounces, 750 mL = 26.4 Imperial fl oz.
How many ounces are in 500 mL?
About 16.91 fl oz, close to a US pint (16 fl oz). A 500 mL water bottle is a common size globally and holds just over an American "pint glass" at a bar.
How many ounces are in 100 mL?
About 3.38 fl oz. The 100 mL limit is relevant for carry-on liquids on airplanes (3.4 fl oz TSA limit matches this almost exactly), and 100 mL is a common skincare-bottle size.
How many ounces are in 50 mL?
About 1.69 fl oz, roughly one US shot and a bit. 50 mL is the "mini bottle" size for spirits (airplane-size liquor bottles).
Why do some sources say 30 mL and others say 29.57 mL per ounce?
The exact conversion is 29.5735 mL per US fluid ounce — everyone agrees on that. But 30 mL is the kitchen shortcut used in recipes and on some cookware labelling, because it's easier to remember and within 1.5% of the real value. For cooking it's fine; for medicine, chemistry, or cocktail recipes where proportions matter, use 29.57.
How many mL in a UK (Imperial) fluid ounce?
28.41 mL per Imperial fl oz — slightly smaller than the US ounce (29.57 mL). The difference comes from how each country defined its gallon after 1824. The UK now mostly uses millilitres, but Imperial fl oz still appears on some traditional pub pours and in older recipes.
Is a fluid ounce the same as a weight ounce?
No — they measure different things. A fluid ounce (fl oz) is volume: 29.57 mL. A weight ounce (oz) is mass: 28.35 grams. They're named similarly because 1 fluid ounce of water weighs almost exactly 1 ounce by weight (a coincidence of the old English unit system). But 1 fluid ounce of honey weighs about 1.4 oz, and 1 fluid ounce of oil weighs 0.9 oz — the fluid-to-weight match only works for water.
How do I convert mL to ounces in my head?
Divide by 30. It's within 2% of the real answer for any amount. A 250 mL glass = about 8 fl oz; a 355 mL soda can = about 12 fl oz; a 750 mL wine bottle = about 25 fl oz. For cooking this shortcut is accurate enough; for anything important use the exact 29.5735.
Related Cooking Conversions
- How many mL in a cup? — 240 mL (US legal)
- How many ounces in a cup? — 8 fl oz
- How many ounces in a shot? — 1.5 fl oz (US)
- How many ounces in a pint? — 16 fl oz
- How many ounces in a quart? — 32 fl oz
- How many ounces in a liter? — 33.8 fl oz
- Cooking Volume to Weight Converter — "How much does an ounce of honey weigh?"
- Cooking Weight to Volume Converter — "Convert grams to mL by ingredient"
- All Cooking Measurement Tools
This page uses the US fluid ounce (29.5735 mL) as its default — the ounce on every US recipe, bottle, and measuring cup. The Imperial (UK) fluid ounce (28.4131 mL) is given for cross-reference; modern UK recipes use millilitres and litres directly. Fluid ounce is a measure of volume; the ounce (oz) as a measure of weight (28.35 g) is a different unit and converts to grams, not millilitres.