Note: Grunt brands the clothing sizes in a slightly different way than many others brands. Below we have created a size guide for Grunt.
| Age and Height | Waist measurement |
| 8 years (128 cm) | 21“ |
| 9 years (134 cm) | 22“ |
| 10 years (140 cm) | 23“ |
| 11 years (146 cm) | 24“ |
| 12 years (152 cm) | 25“ |
| 13 years (158 cm) | 26“ |
| 14 years (164 cm) | 27“ |
| 15 years (170 cm) | 28“ |
| 16 years (176 cm) | 29“ |
| 17 years (182 cm) | 30“ |
| 18 years (188 cm) | 31“ |
