So.. I came home and the whole house smelled of gas as if a stove knob had been left open

I’d call your gas company to ask that question.

yeah the gas company or fire department is your best bet

but once you open the doors and windows it disappates pretty quickly

Can you let us know your when your ok?

Basically until you can no longer smell it, but how it takes to dissipate depends on the size of the rooms and the amount of ventilation you can give them.

This once happened to me, but leaving the front door open and opening the back door wide so the wind could blow through cleared the gas within about half an hour. Mind you, that was a small house: only three rooms in a row downstairs..

I'd probably wait 24 hours eating out all the next day.

Is it natural gas or propane? Natural gas is lighter than air and will dissipate quickly if well ventilated. If you can't smell it anymore, you're good. If it's propane, that's heavier than air and can collect in low areas such as basements. You should call the fire department in that case.

I wish I knew the answer. In my country we can call the fire department or poison control (both non-emergency, meaning NOT 911) and ask that question to someone who knows what they're talking about. Does your country have anything like that?

Wait till you dont smell gas anymore