Convert Diamond Weight to mm Calculator
Approximate Dimensions
Note: These are approximate dimensions and may vary based on the specific cut of the diamond.
Here’s a comprehensive table that converts diamond weights in carats to their approximate sizes in millimeters (mm) for round brilliant cut diamonds:
Diamond Weight to Size Conversion Chart
| Carat Weight | Diameter (mm) |
|---|---|
| 0.25 ct | 4.0 mm |
| 0.30 ct | 4.3 mm |
| 0.40 ct | 4.7 mm |
| 0.50 ct | 5.0 mm |
| 0.60 ct | 5.4 mm |
| 0.75 ct | 5.8 mm |
| 1.00 ct | 6.4 mm |
| 1.25 ct | 6.9 mm |
| 1.50 ct | 7.3 mm |
| 1.75 ct | 7.7 mm |
| 2.00 ct | 8.1 mm |
| 2.50 ct | 8.7 mm |
| 3.00 ct | 9.3 mm |
| 4.00 ct | 10.2 mm |
| 5.00 ct | 11.0 mm |
Key Points to Remember:
- This chart is specifically for round brilliant cut diamonds. Other shapes may have different size-to-weight ratios12.
- These measurements are approximate. The actual size can vary slightly depending on the diamond’s cut proportions13.
- The diameter measurement refers to the width of the diamond when viewed from the top1.
- Carat weight is a measure of a diamond’s weight, not its size. Two diamonds of the same carat weight can appear different in size depending on their cut3.
- As carat weight increases, the diameter doesn’t increase proportionally. For example, doubling the carat weight from 1.00 ct to 2.00 ct only increases the diameter from 6.4 mm to 8.1 mm13.
- When choosing a diamond, consider not just the carat weight, but also how it will look on the wearer’s hand. A 1-carat diamond might look substantial on a small hand but modest on a larger one3.
- The perceived size of a diamond can also be influenced by its setting and the size of the ring band3.
Remember, while this chart provides a good general guide, it’s always best to view diamonds in person or through detailed images when making a selection, as factors like cut quality and proportions can affect how large a diamond appears.