The sentence for arson ranges from 6 months in jail to a year in jail.
And in some cases the sentence for arson can go up to 5 to 6 years in prison and in more severe cases of arson you can be sentenced to 15 years or even more for arson.
The actual sentence for arson is determined on the damage caused if any and whether or not you have a prior criminal history.
If you have no criminal history and it's your first offense without doing any damage then you might get off with 1 year in jail or 6 months in jail or may even just get a fine.
Arson is not always a Violent Crime although in most places Arson is considered to be a Felony and can get you 1 year in prison and up to 10 to 15 years in prison.
If it's your first offense with Arson then you may get off with no jail time and possibly a fine if you did no actual damage or didn't cause any injury or death.
But if you caused damage to a building, injured someone etc then you could get up to 6 years in prison and even 15 years.
There can also be accidental Arson such as you playing with fire and then setting something on fire but not reporting it.
In those cases you may only get a fine and no jail time.
But Arson is being taken seriously now so you should avoid it at all costs.