Oval vs Cushion diamond size

By HeyGema™ · Updated November 5, 2026

In short

A 1 carat oval measures 8.0 x 5.5 mm and a 1 carat cushion 5.6 x 5.6 mm. At the same weight an oval faces up about 19% larger than a cushion. In face-up terms, 1 carat of oval looks like a 1.09 carat round and 1 carat of cushion like a 0.80 carat round.

8.0 x 5.5 mm1 ct oval
5.6 x 5.6 mm1 ct cushion
-19%cushion face-up vs oval

Carat to mm calculator

ShapeGemCaratLength to width

About 5.6 x 5.6 mm

An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.

1 ct oval

8.0 x 5.5 mm

1 ct cushion

5.6 x 5.6 mm

Side by side

1 ct cushion inside 1 ct oval

A 1 carat oval and a 1 carat cushion diamond, to the same scale.

Oval vs Cushion diamond size at the same weight

At the same weight an oval faces up about 19% larger than a cushion. A 1 carat oval measures 8.0 x 5.5 mm and a 1 carat cushion 5.6 x 5.6 mm. A 1 carat oval faces up like a 1.09 carat round, and a 1 carat cushion like a 0.80 carat round.

0.5 carat: Oval length x width: 6.3 x 4.4 mm; Cushion length x width: 4.4 x 4.4 mm; Cushion face-up vs oval: -19%

0.75 carat: Oval length x width: 7.3 x 5.0 mm; Cushion length x width: 5.1 x 5.1 mm; Cushion face-up vs oval: -19%

1 carat: Oval length x width: 8.0 x 5.5 mm; Cushion length x width: 5.6 x 5.6 mm; Cushion face-up vs oval: -19%

1.5 carat: Oval length x width: 9.2 x 6.3 mm; Cushion length x width: 6.4 x 6.4 mm; Cushion face-up vs oval: -19%

2 carat: Oval length x width: 10.1 x 6.9 mm; Cushion length x width: 7.1 x 7.1 mm; Cushion face-up vs oval: -19%

3 carat: Oval length x width: 11.5 x 7.9 mm; Cushion length x width: 8.1 x 8.1 mm; Cushion face-up vs oval: -19%

Carat	Oval length x width	Cushion length x width	Cushion face-up vs oval
0.5 carat	6.3 x 4.4 mm	4.4 x 4.4 mm	-19%
0.75 carat	7.3 x 5.0 mm	5.1 x 5.1 mm	-19%
1 carat	8.0 x 5.5 mm	5.6 x 5.6 mm	-19%
1.5 carat	9.2 x 6.3 mm	6.4 x 6.4 mm	-19%
2 carat	10.1 x 6.9 mm	7.1 x 7.1 mm	-19%
3 carat	11.5 x 7.9 mm	8.1 x 8.1 mm	-19%

Oval vs Cushion on a finger

A 1 carat oval covers 33% of the width of a size 6 finger and a 1 carat cushion covers 34%. Long cuts sit along the finger, so their width is what shows across it.

6.4 mm stone on a 16.5 mm finger: it covers 39% of the widthA 1.5 carat cushion on a size 6 finger.

4: Finger width: 14.9 mm; 1.5 ct oval covers: 42%; 1.5 ct cushion covers: 43%

5: Finger width: 15.7 mm; 1.5 ct oval covers: 40%; 1.5 ct cushion covers: 41%

6: Finger width: 16.5 mm; 1.5 ct oval covers: 38%; 1.5 ct cushion covers: 39%

7: Finger width: 17.3 mm; 1.5 ct oval covers: 36%; 1.5 ct cushion covers: 37%

8: Finger width: 18.1 mm; 1.5 ct oval covers: 35%; 1.5 ct cushion covers: 35%

US ring size	Finger width	1.5 ct oval covers	1.5 ct cushion covers
4	14.9 mm	42%	43%
5	15.7 mm	40%	41%
6	16.5 mm	38%	39%
7	17.3 mm	36%	37%
8	18.1 mm	35%	35%

Match the look, not only the carat

Because a cushion needs about 1.37 carat to face up like 1 carat of oval, comparing by weight alone hides the difference. Compare millimeters, or put both stones side by side in the size comparison tool.

Oval and Cushion size charts

Full charts from 0.25 to 5 carat: Oval diamond size chart and Cushion diamond size chart.

Questions

At the same weight an oval faces up about 19% larger than a cushion. Face-up area is what you see from above; the oval has more of it at equal weight.

A 1 carat oval is about 8.0 x 5.5 mm and a 1 carat cushion about 5.6 x 5.6 mm, for a well-cut stone at the usual ratio.

A 2 carat oval is 10.1 x 6.9 mm and a 2 carat cushion is 7.1 x 7.1 mm. Face-up, the cushion is -19% against the oval.

A 1 carat oval covers 33% of the width of a size 6 finger and a 1 carat cushion 34%. The numbers change with ring size and with the stone's length-to-width ratio.