BOSS Baby sizes 1 - 18 month
| Approximate age | Child's height |
| 1 month | 54 cm |
| 3 month | 60 cm |
| 6 month | 67 cm |
| 9 month | 71 cm |
| 12 month | 74 cm |
| 18 month | 81 cm |
BOSS Junior sizes 2 - 16 year
| Approximate age | Child's height |
| 2 year | 86 cm |
| 3 year | 94 cm |
| 4 year | 102 cm |
| 5 year | 108 cm |
| 6 year | 114 cm |
| 7 year | 120 cm |
| 8 year | 126 cm |
| 10 year | 138 cm |
| 12 year/ XS | 150 cm |
| 14 year/ S | 162 cm |
| 16 year/ M | 174 cm |
BOSS Pre-walker shoes sizes
| Approximate age |  EU |
 UK |
 USA |
| Newborn | 15 | 0.5 | 1 |
| 0-2 month | 16 | 1 | 1.5 |
| 2-4 month | 17 | 1.5 | 2 |
| 4-6 month | 18 | 2 | 3 |
| 6-9 month | 19 | 3 | 3.5 |
| 9-12 month | 20 | 4 | 4.5 |
| 12-18 month | 21 | 4.5 | 5 |
BOSS Junior shoes sizes
| EU |
UK |
USA |
Approximate age |
| 22 | 5.5 | 6 | 18-24 month |
| 23 | 6 | 6.5 | 2 year |
| 24 | 7 | 7.5 | 2 year |
| 25 | 7.5 | 8 | 3 year |
| 26 | 8.5 | 9 | 3 year |
| 27 | 9 | 10.5 | 4 year |
| 28 | 10 | 10.5 | 4 year |
| 29 | 11 | 12 | 5 year |
| 30 | 11.5 | 12.5 | 6 year |
| 31 | 12.5 | 13 | 7 year |
| 32 | 13 | 13.5 | 7 year |
| 33 | 1 | 1.5 | 8 year |
| 34 | 2 | 2 | 8 year |
| 35 | 2.5 | 2.5 | 10 year |
| 36 | 3.5 | 3.5 | 10 year |
| 37 | 4 | 4 | 12 year |
| 38 | 5 | 5 | 12 year |
| 39 | 6 | 6 | 14 year |
| 40 | 6.5 | 6.5 | 14 year |
| 41 | 7.5 | 7.5 | 16 year |