What is an ounces to ml converter?
An ounces to milliliters converter is an online tool that turns a volume measured in US fluid ounces (fl oz) into its equivalent in milliliters (mL), and back again. The fluid ounce belongs to the US customary system, while the milliliter is a metric unit, so this converter bridges the two systems that appear on labels, recipes, and medical instructions around the world.
The tool works in real time: type a value into either field and the other updates automatically, with no “calculate” button to press.
How does it work?
One US fluid ounce is defined as exactly 29.5735 milliliters. To go the other way, one milliliter equals about 0.033814 US fluid ounces. Because both quantities measure the same physical volume, converting between them is a single multiplication.
Note that the US fluid ounce differs slightly from the UK (imperial) fluid ounce, which is about 28.4131 mL. This converter defaults to the US fluid ounce; use the unit selector to switch to the UK ounce when needed.
Formula
To convert US fluid ounces to milliliters:
To convert milliliters to US fluid ounces:
Worked examples
Example 1: 1 fluid ounce to milliliters
So a single US fluid ounce holds 29.5735 mL — a little under a standard 30 mL shot.
Example 2: 100 milliliters to fluid ounces
A 100 mL sample is therefore about 3.38 US fluid ounces.
Conversion table
| Fluid ounces (US) | Milliliters (mL) |
|---|---|
| 1 | 29.5735 |
| 2 | 59.147 |
| 4 | 118.294 |
| 8 | 236.588 |
| 12 | 354.882 |
| 16 | 473.176 |
| 32 | 946.353 |
Notes
- Recipes and nutrition labels often round 1 fl oz to 30 mL for convenience; use the exact factor of 29.5735 when precision matters.
- Confirm whether a source uses US or UK ounces before converting — the two differ by roughly 4%.
- To move between milliliters and cups instead, try the ml to cups converter.
Frequently asked questions
How many ml are in 1 fluid ounce?
There are 29.5735 milliliters in one US fluid ounce.
How many fluid ounces are in 100 ml?
100 milliliters equal about 3.3814 US fluid ounces.
Is a US fluid ounce the same as a UK fluid ounce?
No. A US fluid ounce is 29.5735 mL, while a UK (imperial) fluid ounce is about 28.4131 mL. Select the correct unit before converting.
Why is 1 oz sometimes shown as 30 ml?
Thirty milliliters is a rounded, everyday approximation of the exact 29.5735 mL. It is convenient for quick estimates but is not exact.