Mm To Carat Conversion Calculator



Gemstones are treasured for their exquisite appearances and unique characteristics. To assess their value and quality accurately, gemstone enthusiasts and professionals rely on carat weight as a primary metric. However, gemstones are often measured in millimeters (mm) before being converted into carats. This conversion is necessary to determine their market value, compare different gems, and create stunning jewelry designs.


The formula to convert millimeters (mm) to carats (ct) for gemstones is relatively straightforward:

Carats (ct) = (Length in mm x Width in mm x Depth in mm) / Conversion Factor

The conversion factor may vary based on the type of gemstone and the specific measurement guidelines used by gemologists and jewelers. Typically, it falls within the range of 5 to 7, with 5 being used for denser gemstones like diamonds and 7 for lighter gemstones like emeralds.

How to Use?

Using the MM to Carat Conversion Calculator is a breeze:

  1. Measure your gemstone: Using a precise measuring tool, note down the length, width, and depth of your gemstone in millimeters.
  2. Input the measurements: Enter the measured values into the calculator.
  3. Select the appropriate conversion factor: Determine the appropriate conversion factor based on the type of gemstone you’re working with or follow industry standards.
  4. Calculate the carat weight: The calculator will instantly provide you with the carat weight of the gemstone.


Let’s consider an example to illustrate how the MM to Carat Conversion Calculator works:

Suppose you have an amethyst gemstone with the following measurements:

  • Length: 8 mm
  • Width: 6 mm
  • Depth: 4 mm

Using the formula with a conversion factor of 6:

Carats (ct) = (8 mm x 6 mm x 4 mm) / 6 Carats (ct) = (192 mm³) / 6 Carats (ct) = 32 ct

So, the amethyst gemstone has a carat weight of 32 carats.


Q1: Why is carat weight important in the gemstone industry?

A1: Carat weight is a fundamental factor in determining a gemstone’s value. Larger gemstones are often rarer and more valuable, but other factors like clarity, color, and cut also play significant roles.

Q2: Can I use the same conversion factor for all gemstones?

A2: While a conversion factor of 6 is commonly used for various gemstones, it’s essential to consult industry guidelines or a gemologist for specific gem types, as some may require different conversion factors.

Q3: Are there online tools available for MM to Carat conversion?

A3: Yes, numerous online MM to Carat Conversion Calculators are easily accessible, making the conversion process quick and convenient for gem enthusiasts and professionals.


The MM to Carat Conversion Calculator is an indispensable tool for anyone dealing with gemstones. It simplifies the process of converting measurements from millimeters to carats, enabling accurate assessments of gemstone value and facilitating the creation of stunning jewelry designs. Whether you’re a gem enthusiast or a professional jeweler, this calculator ensures that your gemstones are measured with precision, enhancing their allure and marketability in the world of precious gemstones.

Leave a Comment