On average, a gas bottle typically lasts between 3 to 6 days, though this depends heavily on the season, your campervan model, and appliance usage. Depending on the model, our campervans can generally be equipped with 5kg or 10kg gas bottles.
The stovetop uses the least amount of gas. However, if your campervan has a multi-mode fridge, frequently running it on the gas setting (such as when parked off-grid) will drain the bottle faster. The most significant drain is the Truma combi system (interior air and hot water heater). Running the interior heater overnight during winter will dramatically increase consumption and can easily deplete a bottle in just a few short days, so always monitor your levels closely in cold weather.