The cost of concrete

Decent rule of thumb is whatever the concrete costs, plan on that again for the total.

1yd of concrete ill cover around 81 sq/ft at 4" thick. Call the crete place and get the price per yard and do the math. I paid 8400 2 years ago for my 36x48 shop, 4" thick with 3 cross beams. 1 yard was around $102 at that time. Rebar was around 300.