CAD, BIM and construction calculators

Convert millimetres to inches instantly, with the exact 25.4 factor, fractional inches for US drawing sets, plus the rounding rules drafters use on dimensioned sheets.

1 ft = 304.8 mm exactly. 0.5 ft = 152.4 mm, 1.5 ft = 457.2 mm, 10.5 ft = 3200.4 mm, 11 ft = 3352.8 mm, 15 ft = 4572 mm. Free feet-and-inches to mm converter with full tables.

1 inch = 25.4 mm exactly. 1 in = 25.4 mm, 2 in = 50.8 mm, 5 in = 127 mm, 10 in = 254 mm. Free inches to mm converter with an exact reference table and the rounding rules drafters use on drawings.

1 mm = 0.00328084 ft (1 ft = 304.8 mm exactly). 1 mm = 0.0033 ft, 10 mm = 0.0328 ft. Free mm to feet converter with an exact reference table and the rounding rules drafters use on drawings.

1 foot = 0.3048 m exactly. 1 ft = 0.3048 m, 2 ft = 0.6096 m, 5 ft = 1.524 m, 10 ft = 3.048 m. Free feet to meters converter with an exact reference table and the rounding rules drafters use on drawings.

1 m = 3.28084 ft (1 ft = 0.3048 m exactly). 1 m = 3.2808 ft, 2 m = 6.5617 ft, 5 m = 16.4042 ft, 10 m = 32.8084 ft. Free meters to feet converter with an exact reference table and the rounding rules drafters use on drawings.

Convert square metres to square feet and back with the exact 10.7639 factor, plus per-unit rate conversion for area-based CAD and BIM pricing.

Convert feet-and-inch dimensions (including fractions like 7/16") to decimal feet and decimal inches, for spreadsheets, survey data, Civil 3D and Revit parameters. Full inch-to-decimal table.

Estimate drywall sheets from room dimensions, openings, ceiling area and sheet size. Adjustable waste, 4×8 / 4×10 / 4×12 coverage tables and worked examples. Free, no sign-up.

Calculate concrete volume for slabs, footings and columns in cubic metres, cubic feet and cubic yards, with waste allowance and 25 kg bag counts.

Calculate rebar and steel plate weight in kg and lb from diameter, thickness, length and quantity, using the d²/162 rule detailers apply on bar bending schedules.

Estimate reinforcement weight from bar diameter, length and count: kg per metre, total tonnage and the lap-adjusted figure a bar bending schedule actually orders.

Estimate tiles and boxes from area, tile size, grout joint and waste allowance. Tiles-per-m² table, formula and worked examples. Free, no sign-up.

Estimate paint for a rectangular room from dimensions, openings, coats and the coverage on your paint label. Results in litres and US gallons, with formula and examples.

Estimate gravel volume and weight from length, width and depth. Results in cubic yards, cubic metres and tons with an editable density. Formula, depth table and examples.

Calculate board feet from thickness, width, length and quantity, with optional price per board foot. Formula, common-size table and worked examples.

Convert length × width × depth into cubic yards, cubic feet and cubic metres. Depth table, formula and worked examples for ordering soil, fill, concrete or stone.

Estimate asphalt tonnage from area and compacted thickness with an editable density (145 lb/ft³ default). Optional price per ton, formula and thickness table.

Count concrete blocks (CMU) from wall length, height and openings, with block size and waste allowance. Defaults to 8×8×16 in blocks (1.125 per ft²).

Estimate bricks for a single-leaf wall from area, brick size and mortar joint. Defaults to 215 × 65 mm bricks with 10 mm joints (about 60 per m²).

Calculate floor area ratio, plot ratio and site coverage from gross floor area and plot area, with the buildable-area check planners actually apply.

Every standard drawing sheet size in mm and inches: ISO A0–A4, ANSI A–E and ARCH A–E1. Plus a calculator for the largest scale a plan fits on a given sheet.

Calculate riser count, riser height, total going and stair pitch from a floor-to-floor height, with 2R+G comfort and code compliance checks.

Calculate ramp length, run and gradient from a rise and slope ratio, with 1:12 accessibility and landing checks for accessible route design.

Convert roof rise and run into pitch in degrees, x-in-12 ratio, percentage slope and rafter length, with the slope factor for roof area take-off.

Convert a measurement taken off a scaled drawing to real size and back. Metric ratios (1:20 to 1:1250) and imperial architectural scales (1/8", 1/4", 1/2" = 1'-0") with full reference tables.

Enter rise and run to get slope as percent grade, angle in degrees, 1:X ratio and slope length. Grade-to-degree table, formulas and worked examples for site, ramp and drainage drawings.

Calculate common rafter length from building span, roof pitch (rise per 12) and overhang. Returns rise, angle and total length, with pitch-factor table and formula.

Calculate mid-span deflection, maximum moment and shear for a simply supported beam under a uniform load, and check it against the span/360 and span/250 serviceability limits.

Size ductwork from airflow and target velocity: required cross-sectional area, round duct diameter, equivalent rectangular size and the velocity pressure at that speed.