Ounces to Grams Converter

What this converter does

It converts avoirdupois ounces — the weight unit of American recipes, postal scales and deli counters — into grams, the unit every kitchen scale outside the US displays and every food label worldwide uses. This is the direction you need when cooking American recipes on metric equipment: the recipe says 6 oz of chocolate, the scale speaks grams, and the answer is 170.1.

The formula

Multiply ounces by 28.349523125 to get grams — exactly. The ounce is defined as one sixteenth of the international pound of exactly 453.59237 g, and sixteen divides that cleanly: 28.349523125 g per ounce, with every digit fixed by definition rather than measurement. This tool computes in exact decimal arithmetic, so 16 oz comes out as precisely 453.59237 g, never 453.59236999.

The reverse direction divides by the same number; the grams to ounces page covers it with its own examples and table. Between the two, round trips are exact — convert 4 oz to grams and back and you get 4, not 3.9999.

Worked examples

4 oz of butter → 113.40 g: the quarter-pounder weight, and exactly one American stick of butter. 6 oz of chocolate chips → 170.10 g. 12 oz of flour → 340.19 g, which explains the 340 g jam jar. A 0.5 oz yeast packet → 14.17 g — note US yeast envelopes are actually ¼ oz (7.09 g), a value worth checking on the packet rather than assuming. And the postal case: a 3.5 oz letter → 99.22 g, sliding just under a 100 g postal band.

Entering fractions

American recipes write ounce fractions as fractions: ¾ oz, ⅛ oz. The converter takes decimals, and the mapping is mechanical: ⅛ = 0.125, ¼ = 0.25, ⅓ = 0.333, ½ = 0.5, ⅔ = 0.667, ¾ = 0.75. So 2¾ oz goes in as 2.75 and returns 77.96 g. Any decimal works — the fractions are just the common cases.

Weight or fluid? The single biggest trap

US recipes use “ounces” for two different things: weight (this page) and fluid ounces, a volume of about 29.57 ml. Solids in ounces are weight; liquids in ounces are almost always fluid. Water muddies the intuition because 1 fl oz of water weighs 1.04 oz — close enough that the error hides. It stops hiding with anything denser or lighter: 8 fl oz of honey weighs about 12 oz, and converting that recipe by weight would put half again too much honey in the cake. When a liquid ingredient matters, find the millilitres; when a solid one does, convert here.

Not the silver ounce

Precious metals price in troy ounces — 31.1034768 g, about 9.7% heavier than the ounce this page converts. Scrap dealers weigh in troy ounces and pennyweights; kitchen scales weigh in the avoirdupois world. Selling silver priced by a kitchen conversion shortchanges you by that 10%; the ounces confusion is one-directional in who it costs. The troy pages linked below carry the right constants for metal.

Why US nutrition labels say an ounce is 28 grams

US labelling regulation permits rounding the reference ounce to 28 g, and the convention leaked into charts and packaging worldwide. It is 1.2% light. For calories and salt the error is meaningless; as a conversion factor it is simply wrong, and it is the usual reason two sources disagree about an ounces-to-grams table. This page carries the exact 28.349523125 and rounds only at display, so its table can be checked against any other source digit by digit.

Common mistakes

Multiplying by 28 — the label shorthand, fine for a serving, wrong for a conversion. Reading fluid ounces as weight — the honey problem above. Typing pounds-and-ounces as one number — 1 lb 8 oz is 24 oz, not 1.8 anything; use the two-part converters linked below for that format. And double-converting: recipes republished across the Atlantic sometimes carry both “6 oz” and “150 g” where the metric figure was already rounded — converting the ounces again and getting 170 g means the recipe disagrees with itself, and the sensible move is to pick the metric figure and stay there.

Benchmarks

½ oz = 14.17 g. 1 oz = 28.35 g. 2 oz = 56.70 g. 3 oz = 85.05 g. 4 oz = 113.40 g. 5 oz = 141.75 g. 6 oz = 170.10 g. 8 oz = 226.80 g (the half-pound). 10 oz = 283.50 g. 12 oz = 340.19 g. 16 oz = 453.59 g (the pound). The whole ladder is multiples of the one exact constant.

Accuracy and limits

Exact factor, exact arithmetic, one display rounding under your control. The stated limits: avoirdupois weight only — no fluid ounces, no troy ounces, no cups — because each of those is a different quantity, and the honest job of this page is to convert the one it names and route you correctly for the others.

The stick, the packet and other American units in disguise

US recipes hide ounce weights inside packaging conventions, and decoding them is half the conversion battle. A stick of butter is 4 oz — 113.40 g — and “half a stick” is therefore 56.7 g. The standard yeast envelope is ¼ oz, 7.09 g, near enough the 7 g sachet sold elsewhere. A “square” of baking chocolate in older recipes is 1 oz, 28.35 g. The bag of chocolate chips is 12 oz, 340 g. Translating the container first and the number second turns a cryptic ingredient list into scale-ready grams in one pass through this page.

Postage and small parcels

The other steady user of this direction is mail: US postal pricing steps at ounce boundaries, while almost everyone else prices in grams. A 3.5 oz letter is 99.2 g — under a 100 g band by less than a gram, which is exactly the kind of margin worth converting precisely rather than estimating. Digital kitchen scales double as postal scales for anything under a kilogram; convert the carrier’s ounce thresholds to grams once, keep the list by the tape, and weigh in grams thereafter.

Building a conversion card for the kitchen

Rather than converting every ingredient every time, convert a recipe once and keep the grams column: the CSV download under the table on this page exists for exactly that. A practical card holds the ounce values a cookbook actually uses — 1, 2, 3, 4, 6, 8, 12, 16 — rounded to the nearest gram, because kitchen scales resolve no finer. Rounding to whole grams introduces at most half a gram of error, under 2 percent even on a single ounce, which no recipe can taste. The card is faster than any converter and never runs out of battery mid-bake.