Free construction calculators.
Eight estimators for concrete, lumber, paint, tile, fencing, roofing, decking, and square footage — accurate material quantities and cost planning, no account required.
Bid right, build right, waste less.
Material waste on residential construction projects typically runs 5% to 15% — and that's before unit conversions, rounding errors, and field changes get involved. The math between a quote and a cheque is small, but the wrong number on a takeoff is the difference between bidding profitably and losing money on a job. These calculators take the friction out of that math: enter dimensions, get quantities and costs.
A few real-world fundamentals these tools handle for you. Concrete is sold by the cubic yard in most of North America, but you'll see cubic metres on Canadian supplier tickets — both calculators here output both. Lumber comes in nominal versus actual sizes: a 2×4 actually measures 1.5 × 3.5 inches once it's been planed and dried, and the lumber calculator uses the actual dimensions to give you accurate board footage. Paint coverage averages 350 to 400 square feet per gallon for one coat on a primed wall — less for textured surfaces, less again for dark over light. Drywall ships in 4×8, 4×9, 4×10, and 4×12 ft sheets, and tile installs need roughly a 10% waste factor for cuts around edges, outlets, and patterns.
This category is for the quantity-and-cost side of construction. For Ontario Building Code compliance — beam spans, stair geometry, footing depths, guard heights, egress — see the Ontario Building Code calculators. The two work together: estimate your materials here, then verify the structural and code requirements before you submit for permits.
Eight tools for residential builds.
Construction estimating questions.
A 10×10 ft patio at 4 inches thick needs about 1.24 cubic yards of concrete (or 0.95 cubic metres). The math: 10 × 10 × (4/12) = 33.3 cubic feet, divided by 27 cubic feet per yard. Order an extra 5–10% for waste, spillage, and uneven subgrade — most pros round up to 1.4 yards. Use the Concrete Calculator to handle slabs of any size in either unit.
A "2×4" is a nominal size — the rough dimension before the lumber is planed and dried. The actual size of a finished 2×4 is 1.5 × 3.5 inches. Same goes for other dimensional lumber: a 2×6 is actually 1.5 × 5.5 inches, a 2×8 is 1.5 × 7.25 inches. The Lumber Calculator uses actual dimensions when computing board feet so your order matches what arrives.
Multiply the perimeter of the room by the wall height to get total wall area, then subtract doors (about 20 sq ft each) and windows (about 15 sq ft each). Divide by 350–400 sq ft per gallon for one coat on a primed wall. Plan on two coats for colour changes or new drywall. Textured walls and porous surfaces drop coverage to 250–300 sq ft per gallon. The Paint Calculator handles all of this plus ceilings and trim.
Add 10% waste for straight-set tile on rectangular rooms — that covers cuts at walls, around outlets, and a few breakages. Bump it to 15% for diagonal patterns, herringbone, or rooms with lots of corners and obstacles. Large-format tiles (24"+) and natural stone often need 15–20% because cuts produce more unusable scrap. The Tile Calculator defaults to 10% and lets you adjust.
In Ontario, you generally need a building permit for any deck more than 24 inches above grade, attached to a house, or covering more than 108 sq ft (10 m²). Permit requirements include a site plan, framing details, footing depth, ledger attachment, and guard/stair specs. Estimate materials with the Deck Cost Estimator, then verify code compliance using the Ontario Building Code calculators for footing depth, beam spans, ledger attachment, and guard heights.
One cubic yard equals 0.7646 cubic metres, and one cubic metre equals 1.308 cubic yards. Most concrete suppliers in Canada quote and deliver in cubic metres; in the US, cubic yards are standard. The Concrete Calculator outputs both units so you can match whichever your supplier uses on their delivery ticket.
One roofing square equals 100 square feet of roof surface. To get squares: measure your roof footprint, multiply by a pitch factor (1.06 for 4/12, 1.12 for 6/12, 1.20 for 8/12, 1.42 for 12/12), then divide by 100. A standard bundle of asphalt shingles covers about 33.3 sq ft, so three bundles per square. The Roofing Calculator handles pitch and waste in one step.
Pressure-treated lumber is the most affordable decking material at roughly $3–$6 per square foot for materials. It needs annual cleaning and re-staining to stay looking sharp, but it lasts 15–20 years with maintenance. Cedar is mid-priced ($6–$10/sq ft), composite is $8–$15/sq ft, and PVC tops out at $10–$18/sq ft but is essentially maintenance-free. Compare totals with the Deck Cost Estimator.