Oz to Grams (UK) Converter

The weight ounce is the same in Britain and America. The fluid ounce is not. This page separates the two and converts both.

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Which ounce does a UK label mean?

There are two ounces and only one of them differs between Britain and America. The ounce of weight (avoirdupois) is identical on both sides of the Atlantic at 28.349523125 g. The fluid ounce is not: the UK fluid ounce is 28.4131 mL, the US fluid ounce is 29.5735 mL, a gap of about 4 percent.

Unit	UK value	US value	Difference
Ounce (weight)	28.3495 g	28.3495 g	none
Fluid ounce	28.4131 mL	29.5735 mL	US is 4.1% larger
Pint	568.26 mL (20 fl oz)	473.18 mL (16 fl oz)	UK is 20% larger
Gallon	4.5461 L	3.7854 L	UK is 20% larger

Ounces to grams (weight, identical in both countries)

Ounces (weight)	Grams
0.5 oz	14.17 g
1 oz	28.35 g
2 oz	56.7 g
3 oz	85.05 g
4 oz	113.4 g
6 oz	170.1 g
8 oz	226.8 g
12 oz	340.19 g
16 oz	453.59 g

Fluid ounces compared directly

Fluid ounces	UK (mL)	US (mL)
1 fl oz	28.41 mL	29.57 mL
2 fl oz	56.83 mL	59.15 mL
4 fl oz	113.65 mL	118.29 mL
8 fl oz	227.3 mL	236.59 mL
12 fl oz	340.96 mL	354.88 mL
16 fl oz	454.61 mL	473.18 mL
20 fl oz	568.26 mL	591.47 mL

How to tell which one you are looking at

If the label says fl oz, it is volume. If it just says oz, it is weight.
A British pint glass of 568 mL is 20 UK fluid ounces but 19.2 US fluid ounces.
British beer and milk have historically been sold by the pint; US labels almost always use fluid ounces or millilitres.
For cooking, a 4 percent fluid-ounce difference rarely matters. For a 20-pint brew or a bulk recipe, it does.