I recently got a Weber 330 natural gas grill. I am wondering what the cost to operate this is per hour. It is 38,000 BTU and where I live, natural gas is $4 per Gigajoule. Does anyone know the math to calculate this?

I used to have a propane bbq and a tank here is $15 and would last maybe 12 hours, so operating cost was abit over $1 per hour. Curious if the nat gas grill is cheaper or not.

Gigajoule is close to a therm. It's 947,817 BTU. At FULL flame, if it's 38,000 BTU total, you're looking at over 24 hours for a Gigajoule, or 16 cents/hour.

Propane is about 21,500 BTU/lb for reference, often you get 17 or 15 lbs of propane out of a 20 lb tank, so you're looking at $1+/hr. So if your figures are correct, the NG grill will be much cheaper to run.