It really depends on what you are doing.... I use my propane only when I need to uniformly heat something to a good orange/yellow... The Coal for 90% of all my work. The coal runs at most $20 per hundred and would last four days or so of work. I get about two days out of a normal BBQ grill tank. I do know that charcoal burns faster but it also depends on your blower.... If you want to conserve fuel use a hand cranked blower.