How long does a 20 lb propane tank last on a fire pit?

Community consensus on a typical 50,000 BTU pit is roughly 6–8 hours of burn time per 20 lb tank at full output, and longer if you run the flame lower. Higher-BTU pits (58,000–60,000) drain tanks faster. Several buyers in fire-table discussions specifically cite tank-burn-through speed as a reason they later converted to natural gas.