Carrying, Lifting and Dragging
Adventurers carry a lot of gear. A creature’s Strength score determines how heavy a load it can carry, as well as how much it can push or drag along the ground. A monster’s carrying capacity comes into play only in unusual situations.
Normal Load: Multiply the creature’s Strength score by 10. The result is the weight, in pounds, that the creature can carry around without penalty.
Heavy Load: Double the normal load number (that is, Strength × 20) to find a creature’s heavy load, the maximum weight it can lift off the ground. While a creature is carrying more than its normal load, it is slowed. Carrying such a load requires both hands.
Maximum Drag Load: Five times a creature’s normal load (that is, Strength × 50) is the most weight it can push or drag along the ground. The creature is slowed if it pushes or drags more weight than its normal load, and it can’t push or drag more than its heavy load over difficult terrain.
Published in Player's Handbook, page(s) 222, Rules Compendium, page(s) 265.