The scale that only speaks grams
Most digital kitchen scales are metric. The recipe, though, may be imperial — a half-century-old binder, an American blog, a butcher's portion in ounces. Oz-to-grams is the bridge: oz × 28.3495 = g. Eight ounces of butter is 226.8 g on the display; a 4 oz portion is 113.4 g. The arithmetic is fixed; the only question is whether the source ounce is the ordinary one.
Avoirdupois vs troy: the ounce has a twin
There are two ounces. The avoirdupois ounce — 28.3495 g — is the everyday one for flour, meat, and postage. The troy ounce — 31.1034768 g — is reserved for precious metals and is about 9.7% heavier. They share a name and nothing else useful. Convert a 1 oz gold coin with the 28.35 factor and you call it 28.35 g when it is actually 31.10 g — a meaningful error when bullion is priced per gram. The discipline: if the context is gold, silver, platinum, or gems, use troy (31.1035 g); otherwise use avoirdupois (28.3495 g).
Three places the conversion lands
- Kitchens. Imperial ingredient lists entered into a gram-reading scale — the daily use case.
- Precious metals. Bullion and coin weights, where the troy ounce applies and the factor changes.
- International shipping. An ounce-stated parcel weight expressed in the grams a metric carrier's system expects.
Three worked conversions
Example 1 — a baking portion: 8 oz × 28.3495 = 226.8 g on the scale.
Example 2 — a definition check: 1 oz × 28.3495 = 28.3495 g.
Example 3 — a troy caveat: 1 troy oz × 31.1035 = 31.1035 g, not 28.35 g. Same "ounce", different mass.
Ounce-to-gram reference values
| Ounces (av) | Grams |
|---|---|
| 0.5 oz | 14.1748 g |
| 1 oz | 28.3495 g |
| 2 oz | 56.699 g |
| 4 oz | 113.398 g |
| 8 oz | 226.796 g |
| 16 oz (1 lb) | 453.592 g |
Frequently asked questions
What is the ounces-to-grams factor?
One avoirdupois ounce equals exactly 28.349523125 grams, so the everyday factor is 28.3495. Multiply ounces by 28.3495 to get grams. Round to 28.35 g per oz for cooking.
What is the troy ounce trap in oz-to-grams?
The ounce has a twin. The common avoirdupois ounce is 28.3495 g, but the troy ounce used for gold, silver, and platinum is 31.1034768 g — about 9.7% heavier. If you convert a gold weight with the 28.35 factor you understate it by roughly a tenth, which is a real sum of money. Always confirm whether the source is troy before converting.
Why do I need oz-to-grams if my scale reads grams?
Because many recipes, especially older or American ones, still list ingredients in ounces while the scale on the counter speaks grams. Oz-to-grams is the tranlation step: 8 oz of flour becomes 226.8 g on the display. It is also how precious-metal and international-shipping weights get expressed in the metric unit most scales show.
Engineering context
Oz-to-grams is a fixed-ratio conversion, so the math is safe — the risk is entirely the unit variant. The single most expensive mistake in this corner is applying the avoirdupois factor (28.35) to a troy quantity and understating a precious-metal mass by ~10%. The habit is to tag the ounce type at the source, keep one canonical unit (grams) internally, and convert only at the interface. For the reverse and adjacent mass steps, the same reference covers grams to oz, kg to g, g to kg, and the high-stakes end of the scale at lbs to tons. The full topic is in the Weight & Mass conversion guide.