For a 35lb tumbler—gas consumption per load is 34,853 Btus which is 0.383 cents per load (assumes average cost of natural gas at $1.10 per Therm). Energy to run the motors and control is approximately 0.025 cents per load (assumes 0.065 cents per kWh electricity).
Total cost per load—approximately 0.41 cents.
The answer to this question can get a little tricky, though. Variables come into play beyond our control. Wetness of the load, size of the load and time set on the control. (It takes 25 minutes to dry a common load in this tumbler).