Ml to Oz Converter

A milliliter (mL) is one thousandth of a liter. A fluid ounce (fl oz) is an older unit of volume, and three different ones are in use. This converter divides your mL by the size of the ounce you pick, so one volume gives a slightly different answer under each.

What Milliliter to Ounce Conversion Measures

This tool converts volume, the space a liquid fills. It does not convert weight. A fluid ounce and an ounce of weight are different units, and US nutrition labeling even gives them separate values: 1 fl oz means 30 mL, while 1 oz in weight means 28 g². One mL is also the same as one cubic centimeter (cc), so mL and cc can be swapped freely¹.

The Formula

Each fluid ounce has a fixed size in mL. The US customary ounce is 1/128 of the US gallon, and that gallon is exactly 231 cubic inches, or 3785.411784 mL³. The UK imperial ounce is 1/160 of the imperial gallon, which UK law sets at 4.54609 cubic decimeters⁴.

Fluid ounces = milliliters / mL per fluid ounce

US customary: 29.5735295625 mL per fl oz

UK imperial: 28.4130625 mL per fl oz

FDA nutrition label: 30 mL per fl oz

How This Calculator Computes Your Result

Type a volume in mL. Decimals are fine, and a comma works as the decimal mark (12,5). A comma followed by three digits, as in 1,000, is read as a thousands separator. Pick US, UK or FDA label (US is the default). The tool divides by the exact figure above and rounds only at the end. Results of 1 oz or more show 2 decimals. Smaller results show 3, so they do not round to zero. The card also lists the other two ounces. The swap button opens the Oz to Ml Converter with your result and ounce type filled in.

What Your Result Means

The result is the same volume written in ounces. Here are common sizes under each ounce, rounded as the tool rounds.

For a quick check, divide by 30 and add a little. The US answer is about 1.4% higher than mL / 30. The UK answer is about 5.6% higher.

Which Ounce Should You Use?

Use US customary for US recipes, drinks and bottles. Use UK imperial for British recipes and measures. Use the FDA figure only for US nutrition labels, where the rule applies "for nutrition labeling purposes"². The US ounce is about 4.08% larger than the UK ounce, so a drink is more UK ounces than US ounces.

Where mL Values Show Up in Daily Life

• Hydration. The US National Academies set an adequate intake of total water at 2.7 L a day for women and 3.7 L for men. About 80 percent comes from drinks and 20 percent from food⁵. That is about 91 and 125 US fl oz. These are group averages, not a personal target.

• Baby bottles. Many bottles print mL and oz together. 4 US fl oz is 118.3 mL, so a pair such as 4 oz and 120 mL is rounded.

• Medicine measures. Syringes and dosing cups for liquid medicine are marked in mL. This tool converts volume only and gives no doses. Use the amount and unit on your label, and ask a pharmacist if the units confuse you.

• Skincare and travel bottles. TSA lists carry-on containers as 3.4 oz (100 mL) or less⁶. They are not identical: 100 mL is 3.38 US fl oz, and 3.4 US fl oz is 100.55 mL. Read the size printed on the bottle.

Common Mistakes

• Using 30 as the US factor outside a nutrition label. It adds about 1.4% error.

• Mixing up US and UK ounces. A UK pint is 20 UK fl oz (568 mL), and a US pint is 16 US fl oz (473 mL).

• Treating fluid ounces as weight. A fl oz of honey and a fl oz of water fill the same space but do not weigh the same.