14 calculators · compiled September 2026 · all math in your browser
Construction calculators that speak contractor
Enter the dimensions, get the numbers you actually order with — cubic yards and bag counts, sticks of #4, squares and bundles, tons of hot mix, and cost bands with their assumptions showing. No signup, nothing uploaded; every formula and rule of thumb is documented on the page.
Concrete Calculators
Volume, bags, and steel — order what the pour actually takes.
Roofing Calculators
Pitch, rafters, bundles, and cost bands for the re-roof.
Framing & Interior Calculators
Stair layout, lumber volume, and the drywall count.
Outdoor & Site Calculators
Asphalt tons, fence runs, and retaining-wall blocks.
Concrete Calculators
Slabs, footings, bags, and rebar — the volume-and-steel math for every pour.
Concrete Slab Calculator
Enter slab length, width, and thickness — get cubic yards, 80-lb bag count, and a cost ballpark. Built for shed pads, patios, and garage floors.
Concrete Footing Calculator
Continuous footings and round pier pads: enter dimensions and get cubic yards plus bag counts, sized for deck footings and frost-depth trenches.
Concrete Bag Calculator
Work backwards: enter the volume you need in cubic yards or feet and get exactly how many 80, 60, or 40-lb bags to buy — pallet math included.
Rebar Calculator
Slab rebar grid: enter dimensions, spacing, and bar size — get bar count per direction, total linear feet, 20-ft sticks, and weight.
Roofing Calculators
Pitch, rafter length, shingle bundles, and replacement cost bands for re-roof jobs.
Roof Pitch Calculator
Enter rise and run — get pitch ratio, angle in degrees, slope percentage, the multiplier for roof area, and the pitch chart from 1/12 to 12/12.
Rafter Length Calculator
Enter building span, pitch, and overhang — get the pitched rafter length per side, the run it covers, and a cutting allowance note.
Shingle Calculator
Enter roof footprint and pitch — get roof area, squares of shingles, 3-bundle bundles with waste, and the weight you'll be hauling to the dump.
Roofing Cost Calculator
Roof replacement cost by material, pitch, tear-off, and stories — a low/high band built from 2026 national averages, with the honest caveat to get local quotes.
Framing & Interior Calculators
Stair layout, board-foot lumber volume, and drywall sheets for the build inside.
Stair Stringer Calculator
Enter total rise and tread depth — get riser count, actual riser height, total run, stringer length, and an IRC code check on the riser.
Board Foot Calculator
Lumber volume in board feet: thickness × width × length × pieces, with price-per-bf to get the cost — hardwood pricing without the guesswork.
Drywall Calculator
Room dimensions in — sheets by size (4×8/4×10/4×12), screws, tape, and joint compound out, with door and window deductions and a waste factor.
Outdoor & Site Calculators
Asphalt tons, fence runs, and segmental retaining walls for the site work.
Asphalt Calculator
Driveway area and thickness in — hot-mix tons out, with a $130-220/ton cost band and the 2-inch vs 3-inch driveway thickness reality check.
Fence Calculator
Perimeter in — posts, rail sections, pickets with your gap spacing, and the concrete bags for setting posts out. Wood privacy and picket fences.
Retaining Wall Calculator
Wall length and height in — block count for your block size, cap blocks, base gravel tons, and drain pipe length out. Segmental block walls.
Guides
What Is Roof Pitch
Pitch explained: rise over run, the degrees behind every x/12 value, and the multiplier that converts footprint to roof area.
How to Calculate Concrete Yards
The cubic-yard formula for slabs, footings, and piers, with worked examples and the bag conversion table.
How Many Bundles of Shingles per Square
The 3-bundles-per-square rule, when it's 4 or 5, waste factors by roof complexity, and the tear-off weight math for dumpsters.
Rebar Spacing Rules
Common slab and footing spacings (#4 at 18"), edge cover, lap splices, and where mesh beats rebar — with the code caveat.
Stair Code Basics
IRC R311 in plain language: 7¾" risers, 10" treads, headroom, landings, guards, and handrail heights for deck and interior stairs.
What this site does — and what it does not
It does
- Turn dimensions into orderable quantities — yards, bags, sticks, squares, bundles, tons.
- Show the formulas and the rule-of-thumb sources behind every number.
- Keep every calculation in your browser; nothing you type is stored or sent.
It does not
- Replace stamped engineering details or your local building code — those always win.
- Give quotes — cost bands are national ballparks for budgeting, not prices you can sign.
- Know your soil, your frost line, or your lumber yard's rounding rules. You do.