How many carats are in one avoirdupois ounce?

One avoirdupois ounce equals exactly 141.7476 carats. This is because one avoirdupois ounce equals 28.349523125 grams, and one metric carat equals 0.2 grams (28.349523125 ÷ 0.2 = 141.7476).

How many carats are in one troy ounce?

One troy ounce equals exactly 155.5174 carats. A troy ounce is 31.1034768 grams, and dividing by 0.2 grams per carat gives 155.5174 carats. Troy ounces are heavier than avoirdupois ounces.

What is a metric carat?

A metric carat (ct) is a unit of mass equal to exactly 0.2 grams or 200 milligrams. It is the universal standard for measuring the weight of gemstones, diamonds, and precious stones worldwide, adopted in 1907.

What is the difference between avoirdupois and troy ounces?

The avoirdupois ounce (28.35 g) is used for everyday goods such as food and postal weight. The troy ounce (31.10 g) is used exclusively for precious metals and gemstones. A troy ounce is about 9.7% heavier than an avoirdupois ounce.

Can I convert fractions of an ounce?

Yes. Enter any decimal value such as 0.5 (half ounce) or 2.75. The tool handles fractions to full precision and rounds the carat result to four decimal places for readability.

Ounces to Carats Converter

Name: Ounces to Carats Converter
Availability: InStock
Author: Nham Vu

Enter a weight in ounces and get the exact carat equivalent instantly — supports both avoirdupois and troy ounce types.

Weight Input

Ounce Type

Ounces (oz)

Carats (ct)

Common Conversions

Avoirdupois ounces

oz	ct

1 avoirdupois oz = 141.7476 ct

1 troy oz = 155.5174 ct

1 carat = 0.2 g exactly

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Summary

Enter a weight in ounces and get the exact carat equivalent instantly — supports both avoirdupois and troy ounce types.

How it works

Enter a weight value in ounces in the input field.
Select the ounce type: avoirdupois (common) or troy (precious metals).
The carat equivalent is calculated and displayed immediately.
Use the swap button to convert carats back to ounces.
Copy the result to your clipboard with one click.
Refer to the common conversions table for quick reference values.

Use cases

Determine the carat weight of a gemstone lot purchased in ounces.
Convert precious metal weights for jewelry appraisals.
Verify diamond or ruby weights when bulk buying rough stones.
Calculate how many carats are in a troy ounce of fine gold.
Help jewelers and gemologists switch between unit systems.
Support students studying gemmology or materials science.
Cross-check supplier invoices that mix ounce and carat measurements.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu