All calculators
Construction calculators — concrete, drywall, paint (2026)
Free construction calculators for concrete (slab, post hole, footing, column), drywall (4×8 / 4×12 sheets, mud, tape, screws), paint (smooth, textured, porous surfaces), and fence posts (run length, on-center spacing, gate math). Mobile-first. No account needed.
- How much concrete do I need? Slabs, post holes, footings, and cylindrical columns — output in cubic yards, cubic feet, and 60 lb / 80 lb bag counts. Includes a default 10 % waste factor.
- slab
- post hole
- sonotube
- footing
- bags
- cubic yards
- How many sheets of drywall do I need? Counts sheets (4×8 or 4×12), joint compound gallons, joint tape rolls, screws, and corner bead linear feet. Includes mud waste factor.
- 4x8
- 4x12
- mud
- compound
- tape
- screws
- corner bead
- How many gallons of paint do I need? Inputs wall area or room dimensions, subtracts windows and doors, picks a surface (smooth, textured, porous), and optional primer. Cites drying time.
- gallons
- primer
- coats
- smooth
- textured
- porous
- How many studs and plates do I need for a wall? Inputs wall length, stud spacing (16 in or 24 in on-center), and door/window opening deductions. Outputs total studs plus top, bottom, and sill plate linear feet.
- studs
- framing
- 16 on-center
- 24 on-center
- plates
- sill
- rough opening
- How much rebar do I need for a slab? Counts #3, #4, or #5 deformed bars in a 2-way grid at 12 in or 16 in on-center, plus ACI 318 lap splices for standard 20 ft stock. Multi-slab input for matching pours.
- rebar
- #3
- #4
- #5
- lap
- 12 o.c.
- 16 o.c.
- chairs
- How much does a slab cost? Compares ready-mix $/yd³ against 80 lb / 60 lb bag price for the same pour and picks the cheaper option — shows per-yd³ break-even so you know where the cutover sits.
- cost
- price per yard
- bags
- ready-mix
- break-even
- cheap
- How many decking boards, joists, and beams do I need? Inputs deck length and width, board width (5.5" composite or 5/4x6), joist spacing (16 or 24 in on-center), and stock board length (8/10/12/16/20 ft). Returns board count, decking linear feet, joist count and linear feet, and beam count.
- decking
- boards
- joists
- beams
- 5.5" composite
- 5/4x6
- 16 o.c.
- 24 o.c.
- board length
- How many board feet of lumber do I need? Inputs nominal thickness (in), width (in), length (ft), and pieces — covers any species or stock size from 2x4 studs to 4x4 posts. Optional $/bf pricing returns a one-line cost. Free, mobile-first.
- board feet
- lumber
- bf
- 2x4
- 2x6
- 2x8
- 2x10
- 2x12
- 4x4
- nominal
- How many tiles do I need for a floor or wall? Inputs total area (sq ft), tile size (12×12, 18×18, 6×6, 12×24 stock or custom W×L), waste %, and optional grout width + $ / linear ft. Outputs tile pieces, box count, grout joint, and an optional $/sq ft cost.
- tiles
- floor tile
- wall tile
- 12x12
- 18x18
- 6x6
- 12x24
- boxes
- grout
- porcelain
- ceramic
- How many shingle bundles do I need for a roof? Inputs roof footprint area (sq ft), pitch factor (flat, 6/12, 8/12, 12/12), waste %, and optional $/bundle. Outputs shingle bundles, ridge cap bundles, starter strip bundles, and an optional one-line total cost.
- shingles
- roof
- 3-tab
- asphalt
- ridge cap
- starter strip
- 6/12
- 8/12
- 12/12
- pitch
- slope
- bundles
- How many fence posts do I need for a run? Inputs total fence run length (ft), on-center spacing (ft), post type (line / end / corner / gate), and optional gate count + gate width. Outputs posts broken down by line / corner / gate plus an optional $/post cost — residential MVP uses 8 ft on-center.
- fence posts
- run length
- on-center
- line
- corner
- end
- gate
- depth
- frame
- wood fence
- Concrete calculator for a 10x10, 10x12, or 12x12 slab — cubic yards, 60 lb and 80 lb bag counts, and the depth/thickness answer (4 in for patios, 5–6 in for garages, 6 in with rebar for vehicles). Includes default 10 % waste and links down to the cost estimator.
- 10x10
- 10x12
- 12x12
- slab
- depth
- thickness
- cubic yards
- Drywall calculator for a 12x8 wall — sheet count (4x8 or 4x12), joint compound gallons, joint tape rolls, screw pounds, and corner bead linear feet. Default 1/2 in sheet on a 4x8 stock and 10 % waste. Includes the 1/2 in vs 5/8 in thickness answer.
- 12x8
- 4x8
- 4x12
- sheet
- mud
- tape
- thickness
- 1/2 in
- 5/8 in
- Board foot calculator for a 1x6x8 board and beyond — applies the nominal T × W × L ÷ 144 formula across 2x4, 2x6, 2x8, 2x10, 2x12, and 4x4 stock with the standard surfaced-sizes caveat.
- board foot
- lumber
- 1x6x8
- 2x4
- 2x6
- nominal
- surfaced
- bf