Fire pits that use propane as their primary fuel source will last as long as the propane in your tank does. Different fire pits will consume propane at different rates depending on their make and setting. For the most accurate estimate, check the product's specifications. Generally, one gallon of propane can handle an output of roughly 91,500 BTU. The Ignik FireCan Deluxe, the only propane fire pit on our list, has an output of 38,000 BTU per hour on its highest setting. That means that one gallon of propane will let you use this fire pit for roughly an hour and a half.