Skip to main content
Kalcufy

mL to Fluid Ounces Converter

100 mL is 3.38 fl oz — the same limit written two ways, and the reason cabin baggage rules look different on each side of the Atlantic.

Conversion table

VolumeIn fluid ounces
10.033814 fl oz
20.067628 fl oz
30.10144 fl oz
40.13526 fl oz
50.16907 fl oz
100.33814 fl oz
150.50721 fl oz
200.67628 fl oz
250.84535 fl oz
301.0144 fl oz
401.3526 fl oz
501.6907 fl oz
602.0288 fl oz
702.367 fl oz
752.5361 fl oz

✈️ Sizes you meet constantly

  • 1 US fl oz29.5735 mL
  • 100 mL3.38 fl oz
  • 1 imperial fl oz28.4131 mL
  • 30 mL1.01 fl oz

Bottles, bags and labels

  • A fluid ounce measures volume; an ounce measures weight. They match only for water, and diverge for anything denser or lighter.
  • The carry-on liquids limit is one and the same rule: 100 mL in Europe, 3.4 fl oz in the United States. What matters is the container size, not how full it is.
  • The imperial fluid ounce is the smaller one, 28.41 mL against the American 29.57 — the opposite of what happens with pints and gallons.
  • Cosmetics sold internationally print both: 50 mL / 1.7 fl oz on the same box.

Volume, not weight — and two ounces again

A US fluid ounce is 29.5735 millilitres, defined as one sixteenth of a US pint. The imperial fluid ounce is 28.4131 millilitres, one twentieth of an imperial pint, which makes it the smaller of the two even though every other imperial measure is larger. Both are measures of volume, and neither has anything to do with the ounce of weight at 28.35 grams. The names collided because a fluid ounce of water happens to weigh about an ounce — true enough to cause the confusion, and false enough for anything that is not water.

The 100 mL rule, written twice

Cabin baggage rules for liquids are the same everywhere and only look different because of the unit. European and most international airports set the limit at 100 millilitres per container, with everything fitting in a one-litre transparent bag. The United States expresses the identical rule as 3.4 fluid ounces per container in a quart-sized bag, and 3.4 fl oz is 100.6 mL — the same number rounded outward. The rule is about the size printed on the bottle, so a 200 mL tube with 20 mL left in it is still refused.

Fluid ounces against ounces of weight

  • A US fluid ounce is 29.5735 mL of volume; an ounce is 28.3495 g of mass. Different quantities.
  • They agree for water only: 1 fl oz of water weighs 1.043 oz.
  • 8 fl oz of honey weighs about 12 oz, because honey is 1.4 times denser than water.
  • A recipe saying "4 oz chocolate" means weight; "4 oz milk" means volume. Context is the only clue.
  • Cosmetics labels use fl oz for liquids and oz for creams and balms, which is why a jar and a bottle of the same number are different sizes.
  • Nutrition labels sidestep the problem by using grams for solids and millilitres for liquids.

Container sizes worth recognising

  • Travel bottle limit: 100 mL, printed as 3.4 fl oz in the United States.
  • A perfume sample: 5 mL, or 0.17 fl oz.
  • A standard skincare bottle: 30 mL (1 fl oz) or 50 mL (1.7 fl oz).
  • A can of soft drink: 330 mL in Europe, 355 mL (12 fl oz) in the United States.
  • A shot: 30 mL in most of the world, 44 mL (1.5 fl oz) in the United States.
  • A medicine dosing cup usually carries both scales, in 5 mL and half-fl-oz steps.

Worked examples

Travel bottles and drinks

A 100 mL travel bottle

  1. 100 ÷ 29.5735 = 3.381 fl oz
  2. The US limit of 3.4 fl oz is 100.6 mL
  3. The two rules are the same rule, rounded differently

100 mL = 3.38 fl oz

A 355 mL American can

  1. 355 ÷ 29.5735 = 12.0 fl oz
  2. A European can is 330 mL, or 11.2 fl oz
  3. The American can holds one extra mouthful

355 mL = 12 fl oz

Frequently Asked Questions

How many mL are in a fluid ounce?

29.5735 millilitres for the US fluid ounce and 28.4131 for the imperial one. The imperial is the smaller of the two, which is the reverse of the pint and gallon relationship, because it is a twentieth of a pint rather than a sixteenth.

Is 100 mL the same as 3.4 oz?

Effectively yes, and that is why the cabin baggage limit looks different in different countries. 100 mL is 3.381 fluid ounces, and the American rule rounds it to 3.4. Both describe the same maximum container size.

What is the difference between fl oz and oz?

A fluid ounce measures volume and an ounce measures weight. A US fluid ounce is 29.57 mL; an ounce is 28.35 grams. They coincide only for water, which is exactly why the two names became confusable in the first place.

Does the carry-on limit apply to the bottle or the liquid inside?

To the bottle. Security checks the container's printed capacity, so a 200 mL bottle with only a splash left is still refused while a full 100 mL one passes. Buying travel-sized containers is the only reliable way around it.

How many mL is a shot?

It depends where you are. A US shot is 44 mL, or 1.5 fluid ounces. Most of Europe and Latin America pour 30 mL, and the United Kingdom serves spirits in legally defined 25 mL or 35 mL measures. The word carries no fixed volume.

Why does my skincare bottle say 50 mL / 1.7 fl oz?

Because it is sold in both metric and US markets and the label must be readable in each. 50 mL is 1.69 fluid ounces, rounded to 1.7 on the box. The metric figure is the primary one for products made in Europe.

Sources