25 free calculators for building and DIY projects: concrete and block, framing and stairs, siding and trim, gravel and paving, and lumber. Every calculator shows its formula, a worked example, material and waste notes, and the sources it relies on: building codes such as the International Residential Code (IRC), and industry and manufacturer references such as NCMA for masonry, ICPI for pavers and the American Wood Council for decks.
Planning tools, not approvals. The footing, deck joist span and deck beam span calculators give planning estimates from published span tables and prescriptive methods. Local codes, site conditions and loads vary, so confirm structural sizes with your building department or an engineer before you build.
Concrete & Masonry
Post holes and form tubes, steps, block walls, core fill, mortar, rebar and footings.
- Post Hole & Sonotube Concrete Calculator: Bags or yards of concrete for fence and deck post holes, piers and form tubes.
- Concrete Steps Calculator: Concrete volume and bags for a flight of solid concrete steps with a top landing.
- Cinder Block Calculator (CMU Block Count): How many concrete blocks for a wall, using the NCMA estimating method.
- Block Fill Calculator (Grout for CMU Cores): Grout or core-fill volume for hollow block walls, solid or partly grouted (NCMA TEK 4-2A).
- Mortar Calculator for Block Walls: Bags of mortar mix, or masonry cement and sand, to lay concrete block (NCMA TEK 4-2A).
- Rebar Calculator for Slabs (Grid Spacing & Quantity): Bars, linear feet, weight and 20-ft sticks for a rebar grid in a slab or pad.
- Footing Calculator: Concrete Volume & Deck Footing Size Estimate: Concrete for wall footings, and a planning estimate of deck pad footing size from load and soil bearing. (planning estimate)
Framing, Roofs & Stairs
Studs, rafters, roof pitch, trusses, stairs, and deck joist and beam span estimates from the IRC tables.
- Wall Stud Calculator (Studs, Plates & Headers): Studs, plates and extra framing for a wall at 12, 16 or 24 in on center.
- Rafter Length Calculator (Common Rafters): Common rafter length from span and pitch, with ridge allowance and overhang.
- Roof Pitch Calculator (Rise and Run to Pitch): Pitch, angle, slope percentage and slope factor from any rise and run you can measure.
- Roof Pitch to Degrees Converter (and Degrees to Pitch): Convert x/12 roof pitch to degrees and back, with a full conversion table.
- Roof Truss Calculator (How Many Trusses): Number of roof trusses for a building length at 24 in or 16 in on center.
- Stair Calculator: Rise, Run and Stringer Length: Number of risers, riser height, tread run, stringer length and IRC checks from total rise.
- Deck Joist Span Calculator (IRC Table R507.6 Estimate): Maximum deck joist span for species, size and spacing from the IRC span table. (planning estimate)
- Deck Beam Span Calculator (IRC Table R507.5 Estimate): Maximum deck beam span between posts for beam size, species and joist span. (planning estimate)
Siding, Trim & Drywall Finishing
Siding squares, baseboard and trim, and drywall joint compound and tape.
- Joint Compound Calculator (Drywall Mud & Tape): Gallons and pails of drywall joint compound, plus joint tape, for any wall and ceiling area.
- Siding Calculator (Squares of Siding): Wall and gable area in squares of siding, less windows and doors, plus waste.
- Baseboard & Trim Calculator (Linear Feet and Pieces): Linear feet and number of 8, 12 or 16 ft pieces of baseboard, crown or chair rail.
Site & Landscape
Gravel and crushed stone, fill dirt, sand, asphalt and pavers with their base, in yards and tons.
- Gravel & Crushed Stone Calculator (Yards and Tons): Cubic yards and tons of gravel or crushed stone for a driveway, path, pad or base.
- Fill Dirt Calculator (Cubic Yards and Tons): Fill dirt for a low spot, pad or slope: cubic yards and tons, with a compaction allowance.
- Sand Calculator (Yards, Tons and Bags): Sand for paver bedding, a sandbox or backfill: cubic yards, tons and bags.
- Asphalt Calculator (Tons of Hot Mix): Tons of hot-mix asphalt for a driveway or patch from area and compacted thickness.
- Paver Calculator (Pavers, Base Gravel & Bedding Sand): Pavers, compacted base and bedding sand for a patio, walk or driveway (ICPI Tech Spec 2).
Lumber
Board feet and lumber cost per piece, board foot or linear foot.
- Board Foot Calculator: Board feet for any number of boards, with optional price per board foot.
- Lumber Cost Calculator (Per Piece, Board Foot or Linear Foot): Total cost of a lumber list, and what each board works out to per board foot and per linear foot.
How these calculators are checked
All the calculators run on one small calculation engine with 32 automated tests. Where a source publishes a figure, the test uses it: NCMA’s 119 blocks per 100 sq ft, the IRC deck span tables, the AWC DCA 6 footing sizes, USG’s joint compound coverage and the manufacturer’s concrete bag yields. The build that publishes these pages refuses to run if any test fails. Each page shows the date it was last reviewed.
Last reviewed: 25 September 2026. Something wrong or missing? Please get in touch.