A generator typically uses around 1/2 gallon of gas per hour although some generators may use 1 gallon of gas per hour if it's a larger generator and you have a good load on it.
Small generators may not even use a 1/2 gallon of gas per hour.
For example my 2 stroke generator uses around 1 gallon of gasoline in 5 to 8 hours depending on the load on the generator.
Most generators run between 8 to 10 hours on 5 gallons of gas depending on the size of generator and the load of generator.
If you need to run a generator all the time and at night as well you may want to top off the gas tank before you go to bed or wake up in the middle of the night and then top it off again.
However if I refill my generators gas tank before going to bed then it's still running when I get up the next morning because the load is lighter on the generator.
My 7,000 watt generator will run for at least 10 hours at half load through the night and around 8 hours when I put more of a load on it during the day.
A 7,500 watt generator will usually run for around 10 hours on 5 gallons of gas although it may only run for 8 hours when you have more of a load on the generator.
The more load on the generator the more gas you'll use and the less load on the generator the less gasoline you'll use.
But you should get around 8 to 10 hours on 5 gallons of gas running a 7,500 watt or other large generator.
A generator will usually run about 8 hours to 10 hours on 5 gallons of gas for larger generators.
Smaller generators can usually go 5 hours on a gallon of gas which means it will use around 5 gallons of gas in 24 to 25 hours.
The larger the generator the more fuel it's gonna use and the more load you put on the generator the more gasoline it's gonna use.
Adding gas to a generator while it's running is not recommended although it can be done safely.
The reason why you're not supposed to add gas to a generator while it's running is because you could spill some gas on the hot engine, hot exhaust etc and cause a fire or explosion.
I have however added gas to my generator while it was running for a long time and never had any issue.
I just make sure to pour the gas in slowly and be careful about it.
During a wind storm that took out the power for a week I had a generator running all the time to have electricity and about every 3 hours I would go out and top off the gasoline tank to keep it running.
Never once did I shut the generator down to refuel and it kept running all that time until the power came back on and I shut it off and checked the oil which was also fine.
If you're not sure if you can go without spilling gasoline then it's best to shut the generator off for a few minutes or so and allow it to cool down while you add some fuel.
Although generators can run for a long time it's okay to give it a break once in awhile and it will save you money on gasoline if you don't need it running constantly.
If you don't have enough fuel then you should only run it as much as you need too.
But if you have enough fuel then you can run it all day and all night if you need to or want too.