Construction calculators
6 free tools
Site math without the guesswork — lay out a staircase, count rebar and studs, order the right number of shingle bundles or block, and figure how many bags of concrete fill a post hole. Feet-and-inches friendly and free.
Count the standard 16-by-8 CMU blocks and mortar bags needed for a wall, from its length and height, with a waste cushion.
Count the wall studs at 16 or 24 inches on-center for a given wall length, plus the linear feet of top and bottom plate lumber.
Work out how many 60 or 80 lb bags of concrete fill a cylindrical post hole around your post, from the hole size and post dimension.
Lay out a slab rebar grid — pieces running each way and the total linear feet to order, including an overlap allowance.
Estimate roofing squares and the number of shingle bundles to buy, from your roof area or a footprint and pitch, plus a waste cushion.
Turn a floor-to-floor rise into a full stair layout — step count, riser height, tread depth, and stringer length — with a code check.
Frequently asked questions
Are these estimates accurate enough to buy materials from?
They get you a solid working number for a takeoff — studs, blocks, bundles, bags. Always add a little for waste and off-cuts, double-check against your local building code, and round up when you place the order so you're not one bundle short on a Sunday.
Do the calculators follow building code?
The stair tool flags risers and treads against common IRC limits (riser up to about 7.75 inches, tread at least 10 inches), but code varies by jurisdiction. Treat the checks as a sanity flag, not a stamp of approval, and confirm with your local inspector.
What units do these use?
Mostly feet and inches, since that's what framing lumber, block, and rebar are sold in around the US. Each field is labeled with its unit, so you can read the inputs at a glance before you trust the output.