What's the difference between troy and avoirdupois ounces?

Troy ounces are used for precious metals and gems (1 troy oz = 31.1 g). Avoirdupois ounces are common for everyday items (1 oz = 28.35 g). See [ounces to grams]({/weight/ounces-to-grams/}) for the reverse conversion.

How is gemstone weight measured?

Gemstones are weighed in carats (1 carat = 200 mg = 0.2 g). Using 31.1034768 grams per troy ounce, one carat is approximately 0.00643015 troy ounces.

I'm buying gold jewelry. A ring is listed as 14 grams. How many ounces is that?

This converter gives 14 grams ≈ 0.49 avoirdupois ounces. Precious-metal quotations use troy ounces instead; 14 grams is about 0.45 troy ounces, so check which ounce the seller names.

Why are there different types of ounces for different items?

Historical reasons. Precious metals historically used troy weight for accuracy in trade. Regular goods use avoirdupois. Today, both systems coexist depending on the industry.

Grams to Ounces Converter

Enter a value to instantly convert between weight units.

From

Precision4 dp

1 Gram = 0.0353 Ounce

Key Formulas

Kilogram → Pound

lb = kg × 2.20462

Pound → Kilogram

kg = lb × 0.453592

Gram → Ounce

oz = g × 0.035274

Ounce → Gram

g = oz × 28.3495

Formula

oz = g × 0.03527396

Food packages, recipes, and small parcels may list mass in grams, while US instructions may use avoirdupois ounces. Use this conversion for ordinary ounces; precious metals use the different troy ounce.

Source: NIST SP 811, Appendix B.9

Reviewed by the Convert Calc editorial team · Last reviewed: 2026-08-01 · see our methodology

Frequently Asked Questions

Real-World Examples

A 28.35 gram package is approximately one avoirdupois ounce.

28.35 g = 1 oz

A 5 gram sample weighs about 0.176 avoirdupois ounces on an ounce-based scale.

5 g = 0.1764 oz

1 troy ounce (for precious metals) is 31.1 grams, slightly different from avoirdupois

31.1 g = 1.098 oz

100 grams is a common ingredient or product weight; equals about 3.5 ounces

100 g = 3.527 oz

kg to lbs lbs to kg ounces to grams kg to grams stone to kg

See This in Context

Cooking Science & Lab Baking Ingredient Weight Chart: Cups to Grams