Propane Tank Remaining Usage Calculator

I realized that I was probably replacing the propane tank on our grill with a full tank before we really needed to because I was not sure how much longer it would last so I found out how to calculate the remaining time. This is a very simple way to determine how much remaining time you have in the grill propane tank. You need to know 3 numbers to do it:
Empty tank weight (lbs, 16.6 typical)
Grill BTUs (12000 is typical)
Current tank weight (lbs)
Remaining gas (lbs)
Remaining time (hours)