Free construction calculators
Free Construction Calculators for Your Next Project
Estimate concrete, gravel, mulch, drywall, roofing and more. Every calculator shows its formula, works in US units with metric alongside, and lets you change the allowances.
- Free to use
- No signup
- US customary and metric
Formulas shown
Every result lists the steps behind it.
US units and metric
Feet, inches and yards, with exact metric conversions.
Editable allowances
Waste and compaction are defaults you can change.
Works on your phone
Large inputs and clear numbers on the job site.
Quick takeoffs
Popular construction calculators
Each one shows the formula, accepts feet and inches, and rounds purchase quantities up.
Concrete Calculator
Cubic yards for slabs, round columns, walls and footings, with your own allowance.
Calculate nowBrick Calculator
Bricks for a wall with waste, plus mortar volume and bags.
Calculate nowConcrete Block Calculator
Blocks for a wall with waste, plus mortar bags and optional core fill.
Calculate nowSquare Footage Calculator
Add rectangles, triangles and circles into one total area.
Calculate nowCubic Yard Calculator
Area times depth for soil, mulch, gravel and fill.
Calculate nowCubic Yards to Tons Calculator
Convert yards to tons and back, with material presets or your own density.
Calculate nowGravel Calculator
Cubic yards and tons, with a compaction allowance and an editable density.
Calculate nowMulch Calculator
Cubic yards and bags at the depth you choose.
Calculate nowTopsoil Calculator
Cubic yards, tons and bags for beds, lawns and fill.
Calculate nowDrywall Calculator
Sheets for 4 × 8, 4 × 10 and 4 × 12 boards, plus tape, compound and screws.
Calculate nowTile Calculator
Tiles with grout joints and waste, boxes to buy, and thinset and grout.
Calculate nowPaint Calculator
Gallons for a room, with doors, windows, coats, primer and the ceiling.
Calculate nowRoofing Calculator
Roof area from footprint and pitch, then squares, bundles and underlayment rolls.
Calculate nowRoof Pitch Calculator
Turn rise and run into pitch, angle and the pitch factor.
Calculate nowSiding Calculator
Wall area with gables, minus openings, as squares and boxes or planks.
Calculate nowFence Calculator
Posts, rails, pickets and concrete for a fence run.
Calculate nowDeck Calculator
Board rows, board count and joist layout. Counts only, not structural design.
Calculate nowBoard Foot Calculator
Board feet for a lumber list, by nominal or actual size.
Calculate nowLinear Feet Calculator
Square feet to linear feet by width, plus pieces of trim and boards.
Calculate nowAsphalt Calculator
Tons of asphalt for a driveway or patch from area and compacted depth.
Calculate nowDirectory
Browse by category
Calculators grouped by the kind of job they estimate.
Three steps to a number you can order
Enter your measurements
Decimals, fractions and feet-inches all work, and you can switch to metric.
L: 12′ 6″ W: 10′Check the math
Each step of the formula is listed under the result so you can follow it.
12.5 × 10 × (4 ÷ 12)Get a quantity you can order
Add your allowance. Whole-unit purchases, such as bags and sheets, round up.
41.67 ft³ ÷ 27 = 1.54 yd³
Guides
Construction math, explained
Short explainers that pair with the calculators. See all guides.
How many bags of concrete do I need?
Bags for a slab, a post hole or a cubic yard, worked from the yield printed on the bag.
Read guideHow much gravel do I need?
Cubic yards and tons from area and depth, with typical weights by stone.
Read guideHow to calculate cubic yards
Length times width times depth in feet, divided by 27, with five worked examples.
Read guideHow to calculate roof square footage
Go from the footprint to the real roof area with the pitch factor, then to roofing squares.
Read guideHow BuildLumi works
Formulas you can check
Calculators here estimate quantities. They do not design structures.
Transparent formulas
Each calculator lists the steps from your inputs to the result, so you can verify the math by hand.
Editable assumptions
Waste, compaction, density and bag size are starting points. Change them to match your job and your supplier.
Estimates, not designs
Slab thickness, footing size, spans and loads depend on local code and soil. Ask your building department or a licensed professional.
See how every number is chosen
Sources, exact unit conversions, rounding and allowances are explained on the methodology page. Please read the calculation disclaimer before you order materials.