Carats to Grams Converter

Enter a weight in carats to instantly convert it to grams, milligrams, ounces, troy ounces, kilograms, and pounds.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter the Weight in Carats
Input the carat weight of your gemstone or precious metal into the designated field. For example, '1.5' for one and a half carats.
2
Review Converted Weights
The calculator will instantly display the equivalent weight in grams, milligrams, ounces, troy ounces, kilograms, and pounds.

Example Calculation

A jeweler needs to convert the weight of a 5-carat diamond into grams for inventory and international shipping documentation.

Carats (ct)

Results

1.0000 g

Tips

Understand Carat vs. Karat

Do not confuse 'carat' (ct), a unit of weight for gemstones (1 ct = 0.2 g), with 'karat' (K or kt), a measure of purity for gold alloys (e.g., 24K is pure gold, 18K is 75% gold). They are distinct terms despite similar pronunciation.

Note Precious Metal Units

While this calculator converts to standard ounces (avoirdupois), remember that precious metals like gold and silver are traditionally weighed in troy ounces (ozt), where 1 troy ounce equals approximately 31.1035 grams, slightly heavier than a standard ounce (28.3495 grams).

Factor in Gemstone Density

Carat is a measure of weight, not size. Two gemstones of the same carat weight can appear different in size if they have different densities. For instance, a 1-carat diamond will look smaller than a 1-carat emerald because emerald is less dense.

Precise Weight Conversions with the Carats to Grams Converter

The Carats to Grams Converter is an essential tool for jewelers, gemologists, and anyone working with precious materials, providing instant and accurate weight conversions. By inputting a value in carats, the calculator swiftly translates it into grams, milligrams, ounces, troy ounces, kilograms, and pounds. This comprehensive conversion capability is crucial for inventory management, appraisal, and international trade, ensuring consistent measurements. For example, a 5-carat diamond, a significant gemstone, precisely converts to 1.0000 gram, highlighting the minute scale at which these valuable materials are measured.

Why Specialized Units Matter for Precious Materials

For precious materials like gemstones and metals, specialized units of weight like carats and troy ounces are not merely traditional but fundamentally important for precision, valuation, and preventing confusion in high-stakes commerce. Unlike standard avoirdupois grams or ounces used for everyday goods, these units offer a finer scale or a distinct historical standard. A single carat is a mere 0.2 grams, allowing for minute distinctions in gemstone weight that directly impact value. Troy ounces, heavier than avoirdupois ounces, provide a consistent measure for gold and silver, critical for avoiding ambiguity in global markets where even fractional differences can mean significant monetary value.

The Conversion Logic: Carats to Metric and Imperial Units

The Carats to Grams Converter uses precise conversion factors to translate carat weight into various metric and imperial units. The foundational conversion is from carats to grams, from which all other units are derived.

Carats to Grams:
```
Grams = Carats × 0.2
```
(Since 1 carat = 0.2 grams)
Carats to Milligrams:
```
Milligrams = Carats × 200
```
(Since 1 gram = 1000 milligrams)
Carats to Kilograms:
```
Kilograms = Carats × 0.0002
```
(Since 1 kilogram = 1000 grams)
Carats to Ounces (Avoirdupois):
```
Ounces = Carats × 0.00705479
```
(Since 1 gram ≈ 0.035274 ounces)
Carats to Troy Ounces:
```
Troy Ounces = Carats × 0.00643015
```
(Since 1 gram ≈ 0.0321507 troy ounces)
Carats to Pounds (Avoirdupois):
```
Pounds = Carats × 0.000440925
```
(Since 1 pound = 16 ounces)

💡 Just as this tool converts precise weights, other converters simplify different measurement systems. Our Inches to Centimeters Converter can help you translate length measurements for international contexts.

Converting a 5-Carat Gemstone to Other Weight Units

Consider a 5-carat gemstone that needs to be converted into various other weight units for different purposes, such as customs declarations or sales in different markets.

To Grams: 5 carats × 0.2 g/carat = 1.0000 g.
To Milligrams: 1.0000 g × 1000 mg/g = 1,000.00 mg.
To Ounces (Avoirdupois): 1.0000 g × 0.035274 oz/g = 0.035274 oz.
To Troy Ounces: 1.0000 g × 0.0321507 ozt/g = 0.032151 ozt.
To Kilograms: 1.0000 g / 1000 g/kg = 0.0010 kg.
To Pounds (Avoirdupois): 0.035274 oz / 16 oz/lb = 0.002205 lb.

A 5-carat gemstone weighs exactly 1.0000 gram.

💡 Similar to converting small units of weight, converting small units of length is also a common need. Our Inches to Feet Converter can help you translate linear measurements for various applications.

The Standardized System of Gemstone Measurement

The system of gemstone measurement is highly standardized to ensure global consistency and fair trade. The carat, as a unit of weight, has an intriguing origin, stemming from the uniform weight of carob seeds used by ancient traders in the Mediterranean and Middle East to weigh precious stones. These seeds were remarkably consistent in size and weight, making them a natural early standard. However, regional variations still existed until the early 20th century when the metric carat was internationally adopted, precisely defined as 200 milligrams (0.2 grams). This standardization, finalized in 1907, eliminated ambiguity. For precious metals, troy ounces are the standard, distinct from the more common avoirdupois ounces. One troy ounce equals approximately 31.1035 grams, compared to the avoirdupois ounce at 28.3495 grams. This precise system, established through centuries of trade and formalized by international bodies, underpins the global commerce of high-value materials.

The Ancient Roots and Standardization of the Carat

The carat, the globally recognized unit of weight for gemstones, boasts a rich history rooted in ancient trade practices. Its name and original weight derive from the seeds of the carob tree (Ceratonia siliqua), which were historically used as counterweights by merchants in the Mediterranean and Middle East. These carob seeds were noted for their remarkably consistent size and weight, making them a natural, albeit informal, standard for measuring precious stones.

Over centuries, various regional "carats" emerged, each with slightly different weights, leading to confusion and inconsistencies in the burgeoning global gem trade. The need for a universal standard became increasingly apparent. This standardization effort culminated in the early 20th century with the adoption of the metric carat. In 1907, the Fourth General Conference on Weights and Measures officially defined one metric carat as precisely 200 milligrams (0.2 grams). This crucial decision, championed by organizations like the International Committee for Weights and Measures, provided a uniform, unambiguous measure that has since facilitated transparent and equitable commerce in diamonds and other gemstones worldwide, a standard that remains unchanged in 2025.

Frequently Asked Questions

What is a carat and how does it relate to grams?

A carat (ct) is a standardized unit of mass used for weighing gemstones and pearls. One carat is precisely defined as 200 milligrams (mg) or 0.2 grams (g). This international standard ensures consistency in the global diamond and gemstone trade, allowing for accurate pricing and valuation based on weight, regardless of geographic location or local measurement systems. It's distinct from the purity measure 'karat' for gold.

Why are carats and troy ounces used for precious materials instead of standard grams or ounces?

Carats and troy ounces are specialized units primarily used for precious materials due to historical convention and the need for extreme precision in high-value commerce. The carat (0.2 g) provides a fine scale for gemstones, while the troy ounce (approximately 31.1035 g) offers a consistent, slightly heavier alternative to the standard avoirdupois ounce (28.3495 g) for gold, silver, and platinum. This distinction helps prevent confusion and ensures fair trade within these specific markets.

How does the carat standard ensure fair trade in gemstones?

The international standardization of the carat to exactly 0.2 grams ensures fair trade in gemstones by providing a universal, verifiable unit of weight. Before standardization in 1907, the 'carat' varied slightly across different regions, leading to potential discrepancies in valuation. With a globally recognized metric, buyers and sellers can confidently assess and compare gemstone weights, ensuring transparent and equitable transactions regardless of their respective locations or measurement traditions.

What is the difference between a carat and a point?

In the gemstone industry, a 'point' is a fractional unit of a carat, specifically used for very small gemstones. One carat is equivalent to 100 points. Therefore, a 0.50-carat diamond can also be referred to as a 50-point diamond, and a 0.10-carat stone is a 10-point stone. This smaller unit allows for more precise measurement and discussion of weight for diamonds and other gems under one carat, particularly in retail and wholesale settings.