How many milliliters are in 18 fl oz?

18 US fluid ounces equal 532.32 ml, and 18 Imperial (UK) fluid ounces equal 511.44 ml. Use the US figure for American recipes, nutrition labels and cups; use the Imperial figure in the UK, Ireland, Australia and Canada. They differ because a US fluid ounce is 29.5735 ml while an Imperial fluid ounce is 28.4131 ml.

Is 18 fl oz measured in US or Imperial ounces?

By default, 'fl oz' means US fluid ounces in the United States and Imperial fluid ounces in the UK and Commonwealth. 18 US fl oz is 532.32 ml; 18 Imperial fl oz is 511.44 ml — a difference of 20.89 ml. If a recipe does not say, match it to where the recipe was written.

How many ml is 18 UK fluid ounces?

18 Imperial (UK) fluid ounces equal 511.44 ml. Imperial ounces are about 4% smaller than US ounces, so a British recipe calling for 18 fl oz gives slightly less liquid than 18 US ounces, which would be 532.32 ml.

How many cups is 18 fl oz?

18 US fluid ounces is about 2.25 US cups, since one US cup is 8 fluid ounces (532.32 ml total). It is not a round number of cups, so for baking it is usually easier to measure 18 fl oz directly, or in millilitres: 532.32 ml (US) or 511.44 ml (Imperial).

How do you convert 18 fl oz to ml?

Multiply by the size of one fluid ounce. US: 18 × 29.5735 = 532.32 ml. Imperial: 18 × 28.4131 = 511.44 ml. To go from millilitres back to fluid ounces, divide by the same factor.

Does 18 fl oz of water weigh 532.32 grams?

Roughly, yes. Water is about 1 gram per millilitre, so 18 US fluid ounces (532.32 ml) of water weighs close to 532.32 g. This only works for water and thin water-like liquids; oil, syrup and flour all have different densities, so their weight will not match their volume in millilitres.

18 fl oz in ml

18 fl oz in ml is 532.32 ml using US fluid ounces, or 511.44 ml using Imperial (UK) fluid ounces. Eighteen fluid ounces is a large diner soda, a bit over two US cups. This page gives you both conversions, a live fluid-ounce converter that also handles cups, tablespoons, teaspoons, litres and pints, …

FL OZ CONVERTER

Fluid ounces

Ounce type

1 US fl oz = 29.5735 ml · 1 Imperial fl oz = 28.4131 ml

Convert to

18 US fl oz =

532.32

Milliliter

LIVE DIAGRAM

US FLUID OUNCE

532.32

milliliters

IMPERIAL (UK)

511.44

milliliters

US vs IMPERIAL — 18 FL OZ

US532.32 ml

Imperial (UK)511.44 ml

The US ounce is larger by 20.89 ml (4.1%) at this amount.

VISUAL FILL

1 US cup +

1 US cup = 236.59 ml

Created with❤️byeaglecalculator.com

18 FL OZ IN ML

18 FLUID OUNCES → MILLILITERS

18 US fluid ounces	532.32 ml	× 29.5735 ml
18 Imperial (UK) fluid ounces	511.44 ml	× 28.4131 ml

Eighteen fluid ounces is a large diner soda, a bit over two US cups. Unless a recipe or label says otherwise, US fluid ounces are the default in the United States, while UK, Irish, Australian and Canadian recipes use the slightly smaller Imperial fluid ounce.

18 US FL OZ IN OTHER UNITS

MILLILITERS

532.32 ml

LITRES

0.532 L

US TABLESPOONS

36 tbsp

US TEASPOONS

108 tsp

US CUPS (240 ML)

2.22 cups

HOW TO USE

1
Enter the number of fluid ounces you want to convert — this page starts with 18.
2
Choose whether your figure is in US or Imperial (UK) fluid ounces using the toggle.
3
Pick a target unit — millilitres, litres, cups, tablespoons, teaspoons or pints — and read the result instantly.

GOOD TO KNOW

18 US fluid ounces come to 532.32 ml, while 18 Imperial ounces are 511.44 ml — a gap of 20.89 ml at this size. Because US ounces are the larger of the two, US measurements always yield slightly more liquid than the same count of Imperial ounces.

FREQUENTLY ASKED QUESTIONS

RELATED CALCULATORS

2.5 Cups in ml

Convert instantly →

2 oz in Grams

Convert instantly →

3 oz in Grams

Convert instantly →

2 lbs in Grams

Convert instantly →

Was this calculator helpful?

Last updated: July 28, 2026 · Conversion factors: 1 US fl oz = 29.5735295625 ml, 1 Imperial fl oz = 28.4130625 ml · Verified by the EagleCalculator team · Eagle-eyed accuracy for every calculation.

18 fl oz in ml

FL OZ CONVERTER

LIVE DIAGRAM

18 FL OZ IN ML

18 US FL OZ IN OTHER UNITS

HOW TO USE

GOOD TO KNOW

FREQUENTLY ASKED QUESTIONS

RELATED CALCULATORS

MORE KITCHEN CALCULATORS