Solution: Converting $315_8$ to decimal: $3 imes 8^2 + 1 imes 8^1 + 5 imes 8^0 = 3 imes 64 + 1 imes 8 + 5 imes 1 = 192 + 8 + 5 = 205$. The base-ten equivalent is $oxed{205}$.