At 88% efficiency, the King from Blaze King is the most efficient wood stove in the world. The King has the largest and deepest firebox of any stove on the market. This stove is great for colder climates, larger homes or heating for longer periods of time. You can fit up to 91 lbs. of wood into the King's 4.32cu.ft. firebox. That's equal to 703,390 BTUs of available wood energy.