Ounces to Grams Converter

About the Ounces to Grams Converter

Convert ounces to grams and grams to ounces — type in either box and the other updates. The ounce of food, post and parcels is the avoirdupois ounce, exactly 28.349523125 g (1/16 of a pound of 0.45359237 kg), so grams = oz × 28.349523125 and ounces = g ÷ 28.349523125. 4 oz is exactly 113.3980925 g.

Under the result you see the figure a US Nutrition Facts label would use — labels count 1 oz as 28 g, so 4 oz appears as 112 g — and pounds and ounces for 16 oz or more. Type 1 lb 4 oz or use the Pounds and ounces fields. For gold and silver switch to Troy ounces: a troy ounce is 31.1034768 g, about 10 % heavier. Printable tables cover kitchen amounts in ounces and in grams, postage weights up to a pound, and troy ounces.

Common uses

• Recipes written in ounces (US and UK) cooked with a gram scale, and the other way round.
• Reading a US Nutrition Facts label, which rounds 1 oz to 28 g.
• Weighing letters and parcels against postal limits given in ounces.
• Gold and silver coins and bars priced or sold in troy ounces.

The formula

NIST Handbook 44, Appendix C gives 1 avoirdupois ounce = 28.349 523 125 g and 1 troy ounce = 31.103 476 8 g, both exact (p. C-19), with 16 ounces to the pound (p. C-17).

• grams = ounces × 28.349523125 — 4 oz = 113.40 g
• ounces = grams ÷ 28.349523125 — 100 g = 3.53 oz
• grams = troy ounces × 31.1034768 — 1 oz t = 31.10 g

In your head: 1 oz ≈ 28 g and 100 g ≈ 3.5 oz (each about 1 % off).

Why nutrition labels say 1 oz = 28 g

US food labels do not use the exact figure. Under 21 CFR 101.9(b)(5)(viii), “for nutrition labeling purposes … 1 oz in weight means 28 g” — the same rule makes a cup 240 mL and a tablespoon 15 mL. So a serving declared as 1 oz shows 28 g, and 4 oz shows 112 g although 4 oz is really 113.4 g. The converter shows both.

Ounces and troy ounces

Gold, silver and other precious metals are weighed in troy ounces of 480 grains, 31.1034768 g — 9.7 % more than the ordinary ounce of 437.5 grains. In the UK the troy ounce may be used for trade only in transactions in gold, silver and other precious metals (Weights and Measures Act 1985, section 8). The traditional Indian tola is 180 grains (11.6638038 g), so a troy ounce is exactly 8/3 tola, 2.667 tola.

A fluid ounce is something else again: a volume, not a weight.

About the tables

The kitchen tables list common recipe amounts from 1/4 oz to 2 lb and from 5 g to 1 kg. The postage table runs from 1/2 oz to 1 lb; USPS gives the maximum weight of a First-Class Mail letter as 3.5 oz (99.22 g) and of a large envelope as 13 oz (368.54 g). Prices and other carriers’ weight steps change, so check them before you post.

Limitations

• Ounce means the avoirdupois ounce unless you choose Troy ounces. Fluid ounces (a volume) are not converted here.
• The US label figure (28 g per ounce) is a labelling rule, not a conversion; use the exact grams for recipes and science.
• Postal limits and prices change and differ by carrier; the postage table only converts the weights.
• For tola, masha, ratti and other Indian weights use the Weight Converter.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.