I am thinking of buying an air compressor, and would like some advice from those that own one. At what point does an air compressor graduate from a toy to a useful shop tool? What minimums for CFPM, horsepower and tank size should I be considering?

Well i have multiple..One that is a standalone on a trailer and is as big as a smart car.Another that is a 5 hp and 20 gallon..the other is a 5 gallon and like 2 hp..

The big one is used in my shop and the medium here at home and the small one is for when my buddies and i go off roading..They come in very handy and are very much so a useful tool.Do require maintinece between the compressor its self and all the associatted tools

Simply put, the highest CFPM with the biggest tank you can afford. 220v if you have the service will give you higher CFPM. I don't recall what CFPM mine is, but it was the biggest one I could find but still be 120v. If your going to be using larger air tools, like impact wrenches, air ratchets, air hammers, paint guns. Your going to want a large tank.

Found the pictures of mine.

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I have a 5HP/20 gallon. It'* all you can run at 120V and it doesn't like extension cords. It'* fine for the occasional job but for body repair or long grinding jobs, it gets irritating to wait for the pressure to build back up. I don't know the specs without heading out to the shop, but my experience has been any 120V compressor isn't for anything more than the occasional use.

ive got one like dans, and it does most everything, ive got sanders, die grinders, cut off wheels impact drivers, air hammers. it doesnt seem to be straining to keep up. the only thing i hvaent done is try to sand and paint a whole car if your patient and only going to do it once or twice its fine for everything else. if i had a real shop or was painting all the time id want more capacity

There is a 5/22 on sale for $165 (regular $550) that I am thinking of buying. V, I don't do body work so there won't be many times I will be doing extended sanding.

Thanks for the input.