Contractor Calculators

Free Contractor Calculators for Every Trade

Estimating is where construction jobs are won or lost. Bid too high and the job goes to a competitor; bid too low and you donate your labor to the client. These 18 free contractor calculators exist to make material takeoffs fast, repeatable, and defensible. Each tool uses the same unit conventions your suppliers use — concrete in cubic yards with 80lb bag equivalents, roofing and siding in squares, asphalt by the ton at 145 lb/ft³, brick counts from bedded dimensions with mortar joints — so the number you calculate is the number you order.

Every calculator runs entirely in your browser: enter dimensions, get quantities instantly, and adjust waste factors, prices, and product sizes to match your market. Nothing is uploaded, saved, or paywalled.

Organized by Trade

Concrete & sitework: pours start below grade. Use the excavation calculator for bank and loose yardage (remember the swell factor — common earth expands 25% when dug), gravel for the base, rebar for the grid, concrete for the pour, and asphalt for the driving surface. Together these five tools cover the full sequence from bare dirt to finished pavement.

Framing & structure: the lumber calculator handles board feet and stud counts, the brick calculator converts wall area to brick and mortar quantities across modular, King, and Queen sizes, and the deck, fence, and roof pitch tools close out the structural shell.

Roofing & exterior: roofing squares with pitch multipliers, siding squares with trim and house wrap, and insulation R-values by cavity size — the envelope package in three takeoffs.

Finishing & interiors: drywall sheets and mud, paint gallons per coat, tile with thinset and grout by joint width, mulch by the yard or bag, and electrical loads for the panel schedule.

Why Unit Conventions Matter

• 1 square = 100 sq ft — the universal unit for roofing and siding orders
• 1 cubic yard = 27 ft³ — concrete, gravel, and mulch are sold by the yard
• Asphalt ≈ 145 lb/ft³ compacted — about 0.054 tons per sq yd per inch
• Modular brick ≈ 7 per sq ft with a ⅜ in mortar joint (bedded 8 × 2⅝ in)
• 3 bundles = 1 square for standard-weight shingles

Tips for Accurate Estimates

• Measure twice from the plans, then verify one dimension on site — scale errors multiply everything
• Use realistic waste factors: 5–10% for formed concrete, 10–15% for siding and roofing, 15–20% for diagonal tile
• Price materials the week you bid — lumber, asphalt, and steel move with commodity markets
• Keep the takeoff; a defensible number is your best protection in a change-order dispute
• For anything structural, have an engineer review sizes and spacing — these tools estimate quantities, not structural adequacy