Structural
Structural and strength calculators.
Rebar Weight Calculator
Calculate rebar weight from ASTM A615 bar sizes. Add bars by size, length, and quantity to get the total weight in pounds and tons, plus a per-bar breakdown and optional cost. Free, no sign-up.
Steel Weight Calculator
Calculate steel weight for plate, bar, tube, pipe, and angle from dimensions. Add multiple pieces to get the total weight in pounds and tons, with a per-piece breakdown and optional cost. Free, no sign-up.
Concrete Calculator
Calculate concrete for slabs, footings, walls, columns, and sonotubes. Add pours to get total cubic yards, the number of 40/60/80 lb bags, a waste allowance, and ready-mix cost. Free, no sign-up.
Joist Span Calculator
Find the maximum allowable floor or deck joist span from the IRC span tables. Pick species, grade, size, and spacing to get the code max span by joist size and check it against the span you need. Free, no sign-up.
Deck Beam Span Calculator
Size a built-up deck beam from the IRC R507.5 table. Pick the species and the deck joist span it carries to get the maximum span for double and triple 2× beams and the minimum size for your post spacing. Free, no sign-up.
Rafter Span Calculator
Find the maximum horizontal roof rafter span from the IRC R802.4.1 tables. Pick the roof or ground snow load, species, grade, size, and spacing to get the max span by size and the minimum rafter for your roof. Free, no sign-up.
Ceiling Joist Span Calculator
Find the maximum ceiling joist span from the IRC R802.5.1 tables. Pick the attic use, species, grade, size, and spacing to get the max span by size and the minimum joist for your ceiling. Free, no sign-up.
Stair Stringer Calculator
Enter the total rise to get the number of risers, the riser height, tread count, total run, and stringer length, with an IRC R311.7 code check on riser and tread. Free, no sign-up.
Concrete Block (CMU) Calculator
Estimate a CMU wall from its size: block count, mortar (cement + sand), core-fill grout, and rebar for 6, 8, and 12 in units per NCMA TEK 14-13. Subtract openings and add a waste allowance. Free, no sign-up.
Insulation Calculator
Find the DOE-recommended R-value for your climate zone and assembly, then the insulation thickness, blown-in bags or batt area, and cost — attic, wall, and floor per the 2021 IECC. Free, no sign-up.
Mortar Calculator
Estimate mortar for brick and block: bags of premixed mortar, or masonry cement and sand, by unit count or wall area. Includes Type N, S, M, O mix ratios per ASTM C270. Free, no sign-up.
Stucco Calculator
Estimate 3-coat stucco: bags of scratch, brown, and finish coat, or field-mixed cement and sand, from your wall area. Per ASTM C926 / SMA thicknesses. Free, no sign-up.
Drywall Calculator
Estimate drywall: sheets, screws, joint tape, and joint compound (mud) from your area or room size. Pick 4×8, 4×10, or 4×12 panels with a waste allowance. Free, no sign-up.