Time Scales

Picking a lock takes 1d10 rounds, as stated in the Player's Handbook. If the thief has no lockpicks or is using improvised lockpicks, this duration becomes 1d20 rounds.

Other ways of bypassing locks take rather longer. Using a lock chisel and hammer takes one turn; metal-eating acid takes 3d6 rounds; cutting around a lock takes 2d6 turns (assuming that the door is a wooden one of average thickness cutting through a lock takes 3d6 turns. The DM may roll randomly for time needed, or may select a value within the range shown which reflects the quality and size of the lock. Size will most affect acid and cutting round a lock, whereas quality will affect cutting through a lock, as regards time needed.