How do I calculate the amount of rebar I need for a concrete slab?

What's the slab for? If it's a driveway, use 6x6x#10 woven wire mesh. It comes in sheets that are easy to lay in place, and you pull them up into the pour as you go with the hook on the back of your come along. I wouldn't necessarily use bar unless you were pouring an industrial floor. Hope this helps.

EDIT: Get a 4000 p.s.i. mix, full air entrained, and you will be fine with the mesh instead of rebar. Keep the surface moist for a week, and don't drive on it for 2 weeks, and it will hold up well. You could, and probably should, break it halfway down the length and put in an expansion joint, but that's up to you. Good luck.

RE:

How do I calculate the amount of rebar I need for a concrete slab?

I am going to pour a 65 by 21 concrete slab and I need to know how much rebar I will need. The total square feet is 1365.

Thanks

Rebar Calculator

how many rebar i need if iam going to pour a concret slab at 4500 square feet.

thnks.

I agree with woodtick. Rebar will cause your driveway to split in a few years. Are you doing one pour or several? Several is better with a seam between each pour.

30x50 two foot centers