How many grams are in an ounce? Standard and troy conversions

Ounces-to-grams conversion chart

For ordinary food, package and body-weight measurements, ounce normally means the standard avoirdupois ounce. The exact conversion is 28.349523125 grams per ounce, although 28.35 grams is precise enough for most everyday uses.

Multiply the number of ounces by 28.3495. The chart below uses that standard conversion and rounds sensibly for quick reference.

• 1/8 ounce = 3.54 grams
• 1/4 ounce = 7.09 grams
• 1/2 ounce = 14.17 grams
• 1 ounce = 28.35 grams
• 2 ounces = 56.70 grams
• 4 ounces = 113.40 grams
• 8 ounces = 226.80 grams
• 16 ounces = 453.59 grams, or 1 pound

How to convert ounces to grams

Start with the weight in ounces and multiply it by 28.3495. For example, 3 ounces multiplied by 28.3495 equals 85.0485 grams, which you can round to 85.05 grams.

For a fast estimate, multiply by 28 instead. This shortcut is useful for mental math, but it becomes less accurate as the number of ounces grows. Use the full factor for recipes, shipping labels or any calculation where precision matters.

How to convert grams to ounces

To reverse the conversion, divide the number of grams by 28.3495. A 100-gram item weighs about 3.53 ounces because 100 divided by 28.3495 is approximately 3.527.

Another useful reference is 1 gram = about 0.035274 standard ounces. Keep extra decimal places during the calculation and round only the final result to avoid unnecessary error.

Standard ounce vs. troy ounce

A standard ounce and a troy ounce are not the same size. The standard avoirdupois ounce used for food and most goods is 28.3495 grams. A troy ounce is 31.1034768 grams and is primarily used to price gold, silver, platinum and other precious metals.

If a gold price is quoted per ounce, it almost always means a troy ounce. Using the standard conversion would understate the mass by about 2.75 grams, so always check which ounce the seller or market uses.

• Standard ounce: 28.349523125 grams
• Troy ounce: 31.1034768 grams
• Difference: about 2.754 grams

Why fluid ounces do not convert directly to grams

An ounce without the word fluid is a unit of mass or weight. A fluid ounce is a unit of volume. Grams measure mass, so the gram weight of one fluid ounce changes with the density of the liquid or ingredient.

One US fluid ounce of water weighs about 29.57 grams near room temperature, but the same volume of oil, honey or milk weighs a different amount. For a reliable fluid-ounce-to-gram conversion, identify the substance and use its density rather than treating every liquid like water.

Which number should you use in a recipe?

When a recipe lists ounces next to a solid ingredient, it usually means weight, so use 28.35 grams per ounce and a kitchen scale. When it lists fluid ounces for a liquid, use a measuring cup or convert with the ingredient's density.

A scale is usually more consistent than measuring dry ingredients by cups because flour, sugar and other foods settle differently. If the recipe already provides grams, follow that measurement directly instead of converting back and forth.

Sources

Primary and official references used for this guide:

• NIST Guide to the SI — official ounce conversion factor
• NIST Handbook 44 (2026) — general tables of measurement units
• NIST — precious-metals conversion information