American recipes, nutrition labels and retail packaging routinely list weights in ounces — a unit most of the world's kitchens and scales don't use. This tool converts ounces into grams for anyone working across that divide.
Two ounces, one name — this tool uses the everyday one
The ounce most people encounter daily — on a food scale, a nutrition label, a package of deli meat — is the avoirdupois ounce, equal to 1/16 of the avoirdupois pound, standardized alongside the rest of the English trade weight system centuries ago. A separate, heavier troy ounce persists specifically for precious metals, a holdover from medieval bullion and coinage trade that never merged with the everyday system. Because both are called simply "ounce" in casual speech, mixing them up is a genuine (if usually low-stakes) source of confusion.
The conversion math
1 avoirdupois ounce = 28.3495 grams, derived from the pound's exact 453.59237-gram definition divided evenly by 16. The tool multiplies your ounce value by this constant to produce a precise gram result.
Where this conversion is genuinely practical
- Following a metric recipe with an ounce-labeled kitchen scale — or the reverse, converting an American recipe's ounce measurements to grams for a scale that only displays metric.
- Comparing product sizes across countries — a U.S. product labeled "16 oz" and an international equivalent labeled "450g" are close but not identical, and precise conversion clarifies the real difference.
- Nutrition and macro tracking apps — many fitness and diet apps default to grams for protein, carbs and fat, requiring ounce-based food labels to be converted for accurate logging.
- Postal and shipping weight limits — some carriers price by ounce brackets domestically but require gram-based declarations for international shipments.
Frequently asked questions
Is this the same ounce used for gold prices? No — gold, silver and other precious metals are priced using the troy ounce (about 31.1 grams), roughly 10% heavier than the avoirdupois ounce this tool converts; using the wrong one in a financial context would meaningfully misstate value.
Why is 28.3495 not a rounder number? Because the ounce and gram come from entirely separate historical systems (English trade weight versus French decimal metric) that were only reconciled mathematically once international standards bodies fixed exact conversion constants in the 20th century.
What's a fast approximation for cooking? Many recipes round 1 oz to "about 28g" or even "about 30g" for convenience — fine for casual cooking, but precise baking (especially with leavening agents) benefits from the exact 28.3495 figure this tool provides.
Further reading
Wikipedia — Ounce — Full breakdown of avoirdupois versus troy ounce definitions and uses.