How Many Carats Is An 11 mm Diamond?
An 11 mm round brilliant weighs about 4.95 ct. See how depth changes it, the weight in grams and cents and the sizes around it, then adjust the stone below.
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Round brilliant estimate. Size charts from Stuller (May 2025) and Walt's Jewelers, checked 9 November 2026.
Your stone
Shape
Measured across the girdle. On a certificate, average the smallest and largest diameter.
Table to culet, in mm or as a % of the diameter. Leave it blank to assume 61%, typical for a well-cut round.
Estimated weight
Round, 11 mm
4.95 ct
About 0.991 g · 495 cents
- Formula
- 11² × 6.71 × 0.0061
- Total depth
- 6.71 mm (61.0%)
- At 59–63% depth
- 4.79–5.12 ct
- In grams
- 0.991 g
- In cents (points)
- 495
Typical sizes for well-cut rounds
| Weight | Trade charts | Formula, 61% |
|---|---|---|
| 4.00 ct | 10.2 mm | 10.24 mm |
| 5.00 ct | 11 mm | 11.03 mm |
| 6.00 ct | 11.7 mm | 11.73 mm |
Diameters from Stuller's size chart (2025) and Walt's Jewelers' chart. The closest is highlighted.
An estimate from the stone's measurements. A thick girdle or a bulging pavilion adds weight; weigh a loose stone to be sure.
How to use it
Measure the stone across the girdle. 11 mm is filled in for you; change it to your stone's size.
Add the total depth from the certificate if you have it, or leave it blank to assume 61%.
Read the weight in carats, grams and cents, and compare it with the trade charts.
11 mm round diamond weight at a glance
An 11 mm round brilliant cut to a typical 61% depth (6.71 mm) weighs about 4.95 ct by the standard formula: 11 × 11 × 6.71 × 0.0061. That is 0.991 g, or 495 cents. Trade size charts from Stuller and Walt's Jewelers put an 11 mm round at 5.00 ct.
Weight by depth
| Depth | Depth in mm | Weight |
|---|---|---|
| 59% | 6.49 mm | 4.79 ct |
| 61% | 6.71 mm | 4.95 ct |
| 63% | 6.93 mm | 5.12 ct |
A deeper stone hides more of its weight below the girdle, so it faces up smaller for its weight. Well-cut rounds are usually between about 59% and 63%.
Sizes around 11 mm
| Diameter | At 61% depth | At 59–63% | Cents |
|---|---|---|---|
| 10.7 mm | 4.56 ct | 4.41–4.71 ct | 456 |
| 10.8 mm | 4.69 ct | 4.53–4.84 ct | 469 |
| 10.9 mm | 4.82 ct | 4.66–4.98 ct | 482 |
| 11 mm | 4.95 ct | 4.79–5.12 ct | 495 |
| 11.1 mm | 5.09 ct | 4.92–5.26 ct | 509 |
| 11.2 mm | 5.23 ct | 5.06–5.40 ct | 523 |
| 11.3 mm | 5.37 ct | 5.19–5.55 ct | 537 |
Other shapes and sizes
For an oval, pear, princess or other fancy shape, or to find the size for a carat weight, use the diamond mm to carat calculator. One size down is 10 mm; one size up is 12 mm.
FAQ
Questions
How many carats is an 11 mm round diamond?
About 4.95 ct by the standard formula (diameter² × depth × 0.0061) with a typical 61% depth of 6.71 mm. Trade size charts from Stuller and Walt's Jewelers put an 11 mm round at 5.00 ct.
How much does depth change the weight of an 11 mm diamond?
At 59% depth (6.49 mm) it weighs about 4.79 ct and at 63% (6.93 mm) about 5.12 ct, a spread of about 7%. That is why two 11 mm stones can be sold as different weights. Enter the real depth in the calculator for a closer figure.
What is an 11 mm diamond in grams and cents?
About 0.991 g and 495 cents (points), because 1 carat is 0.2 g and 100 cents.
How do I check that a diamond is really 11 mm?
Measure across the girdle with a millimetre gauge, or read the measurements on the grading report, written like 10.98–11.02 × 6.71 mm (smallest and largest diameter × depth). Use the average diameter and the total depth in the calculator.
Does an 11 mm lab-grown diamond weigh the same?
Yes, if it is cut the same. Lab-grown and natural diamonds are the same material with the same density, so an 11 mm lab-grown round at 61% depth also weighs about 4.95 ct. Moissanite weighs less and cubic zirconia more at the same size.
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