O'Neill Size Chart
Men's Wetsuits
| Size | Height | Weight (Ibs) | Chest | Waist |
| XS | 5'7" - 5'9" | 125 - 140 | 36.5 - 37.5 | 28.5 - 29.5 |
| S | 5'8" - 5'10" | 135 - 155 | 37.5 - 39 | 29.5 - 31 |
| ST | 6'0" - 6'2" | 145 - 165 | 37.5 - 39 | 29.5 - 31 |
| MS | 5'6.5" - 5'8.5" | 145 - 165 | 39 - 41 | 31 - 33 |
| M | 5'9" - 5'11" | 155 - 170 | 39 - 41 | 31 - 33 |
| MT | 6'1" - 6'3" | 160 - 180 | 39 - 41 | 31 - 33 |
| LS | 5'7.5" - 5'9.5" | 160 - 180 | 41 - 43.5 | 33 - 35 |
| L | 5'10" - 6'0" | 170 - 190 | 41 - 43.5 | 33 - 35 |
| LT | 6'2" - 6'4" | 180 - 200 | 41 - 43.5 | 33 - 35 |
| XLS | 5'8.5" - 5'10.5" | 180 - 200 | 43.5 - 46 | 35 - 37 |
| XL | 5'11" - 6'1" | 190 - 210 | 43.5 - 46 | 35 - 37 |
| XLT | 6'3" - 6'5" | 200 - 220 | 43.5 - 46 | 35 - 37 |
| XXLS | 5'9.5" - 5'11.5" | 200 - 220 | 46 - 48.5 | 37 - 39 |
| XXL | 6'0" - 6'2" | 210 - 230 | 46 - 48.5 | 37 - 39 |
| XXXL | 6'0" - 6'3" | 230 - 250 | 48.5 - 51 | 39 - 44 |
| 4XL | 6'1" - 6'4" | 250 - 270 | 51 - 53.5 | 44 - 48 |
Women's Wetsuits
| Size | Height | Weight (Ibs) | Chest | Waist |
| 2 | 5'1" - 5'3" | 90 - 105 | 30 - 32 | 24.5 - 26.5 |
| 4 | 5'3" - 5'5" | 100 - 115 | 30.5 - 32.5 | 25 - 27 |
| 6S | 5'2.5" - 5'4.5" | 105 - 120 | 31.5 - 33.5 | 26 - 28 |
| 6 | 5'4" - 5'6" | 110 - 125 | 31.5 - 33.5 | 26 - 28 |
| 8S | 5'3.5" - 5'5.5" | 115 - 130 | 32.5 - 34.5 | 27 - 29 |
| 8 | 5'5 - 5'7" | 120 - 135 | 32.5 - 34.5 | 27 - 29 |
| 8T | 5'6.5" - 5'8.5" | 125 - 140 | 32.5 - 34.5 | 27 - 29 |
| 10S | 5'4.5" - 5'6.5" | 125 - 145 | 34 - 36 | 29 - 30.5 |
| 10 | 5'6" - 5'8" | 130 - 150 | 34 - 36 | 29 - 30.5 |
| 10T | 5'7.5" - 5'9.5" | 135 - 155 | 34 - 36 | 29 - 30.5 |
| 12S | 5.5.5" - 5'7.5" | 135 - 155 | 35.5 - 37.5 | 30.5 - 32 |
| 12 | 5'7" - 5'9" | 140 - 160 | 35.5 - 37.5 | 30.5 - 32 |
| 12T | 5'8.5" - 5'10.5" | 145 - 165 | 35.5 - 37.5 | 30.5 - 32 |
| 14 | 5'8" - 5'10" | 150 - 170 | 37 - 39 | 31 - 33.5 |
| 16 | 5'9 - 5'11" | 165 - 185 | 38.5 - 40.5 | 33.5 - 35 |
Youth Wetsuits
| Size | Height | Weight (Ibs) | Chest | Waist |
| 1 | 2'10.5" - 3'2.5" | 25 - 30 | 19 - 21 | 18 - 20 |
| 2 | 3'2.5" - 3'6.5" | 30 - 35 | 20 - 22 | 19 - 21 |
| 3 | 3'6.5" - 3'10.5" | 35 - 40 | 21 - 23 | 20 - 22 |
| 4 | 3'10.5" - 4'1.5" | 40 - 55 | 23 - 25 | 20 - 22 |
| 6 | 4'1.5" - 4'4.5" | 50 - 65 | 24.5 - 26.5 | 21.5 - 23.5 |
| 8 | 4'4.5" - 4'7.5" | 60 - 75 | 26 - 28 | 23 - 25 |
| 10 | 4'7" - 4'10" | 75 - 90 | 28 - 30 | 23 - 25 |
| 12 | 4'10" - 5'1" | 90 - 105 | 29 - 31 | 25 - 27 |
| 14 | 5'1" - 5'4" | 105 - 120 | 31 - 33 | 27 - 29 |
| 16 | 5'4" - 5'6" | 120 - 135 | 33 - 35 | 28 - 30 |