How many watts do I need to heat a room?

Most full-size electric space heaters top out at 1500W, which is generally rated for rooms up to about 150–270 sq ft depending on insulation and ceiling height. For a desk or small bedroom, a 500–750W unit is often enough and pulls less from the circuit. Anything labeled to heat a 'large room' on a single 120V plug is still capped at 1500W by code.