Imperial Fluid Ounces to Milliliters (fl oz (UK) to mL)

1 imperial fluid ounce equals 28.4130625 milliliters exactly.

1 imperial fluid ounce = 28.4130625 milliliters

How to convert imperial fluid ounces to milliliters

To convert imperial fluid ounces to milliliters, multiply the number of imperial fluid ounces by 28.4130625. This factor is exact. To go the other way, multiply milliliters by 0.03519507973 (rounded).

milliliters = imperial fluid ounces × 28.4130625

Example: 10 imperial fluid ounces = 284.130625 milliliters.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

Imperial Fluid Ounce (fl oz (UK))

Imperial (British)Current unit

Exactly 28.4130625 mL. About 4% smaller than the US fluid ounce.

Imperial fluid ounce comes from the 1824 reform that defined the British gallon as the volume of ten pounds of water. Because a gallon was set at 160 fluid ounces, an ounce of water weighs about one ounce of mass, around 28.35 grams. That neat link between volume and weight was the point of the imperial scheme, and it explains why people long thought of fluid ounces and weight ounces as nearly the same.

Today an imperial fluid ounce is exactly 28.4130625 milliliters, one twentieth of an imperial pint. That is about 4 percent smaller than the US fluid ounce at 29.57 mL, so a US recipe using fluid ounces does not map one-for-one onto a British one. UK trade rules restricted its use in 1995, and it lives on mostly on older labels, in bars and in recipes. Twenty of them fill an imperial pint, which makes the pint the easiest way to picture one.

1 imperial fluid ounce = 0.0284130625 liters (exactly).

Sources: Wikipedia: Fluid ounce; UK Weights and Measures Act 1985, Schedule 1

Milliliter (mL)

Metric (SI)Current unit

One thousandth of a liter, or exactly 1 cubic centimeter. Used for medicine, cooking and small containers.

Milliliters inherit everything from the liter, since the prefix simply means one thousandth. Because the liter is a cubic decimeter, a milliliter works out to exactly one cubic centimeter, a coincidence the metric system built in on purpose so that volume, length and mass interlock. One milliliter of water has a mass of about one gram, so a dosing syringe, a kitchen scale and a measuring jug can all be checked against one another.

Today milliliters dominate wherever small amounts must be measured precisely: medicine, flavorings, perfume, shampoo and the fine print on drink labels. Spelling is a mild regional split, with uppercase mL preferred in the United States, Canada and Australia and lowercase ml common in the UK and Europe. For scale, a US teaspoon is just under 5 mL, a US tablespoon is about 14.8 mL, and the US nutrition-label cup is exactly 240 mL, so one such cup is 240 of these tiny units.

1 milliliter = 0.001 liters (exactly).

Sources: Wikipedia: Litre; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures

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