450 Boost run true to size. SEE SIZE GUIDE BELOW. Size Chart BelowMen 4 | Women 5 | UK 3.5Men 5 | Women 6 | UK 4.5Men 6 | Women 7 | UK 5.5Men 7 | Women 8 | UK 6.5Men 8 | Women 9 | UK 7.5Men 9 | Women 10 | UK 8.5Men 10 | Women 11 | UK 9.5Men 11 | Women 12 | UK 10.5Men 12 | Women 13 | UK 11.5Men 13 | Women 14 | UK 12.5Men 4.5 | Women 5.5 | UK 4Men 5.5 | Women 6.5 | UK 5Men 6.5 | Women 7.5 | UK 6Men 7.5 | Women 8.5 | UK 7Men 8.5 | Women 9.5 | UK 8Men 9.5 | Women 10.5 | UK 9Men 10.5 | Women 11.5 | UK 10Men 11.5 | Women 12.5 | UK 11Men 12.5 | Women 13.5 | UK 12