Construction Calculator Tools: 24 Free Calculators for Contractors

What a construction calculator is actually for

A construction calculator does one job: it turns a measurement into a quantity you can buy. Square feet become gallons. Roof area becomes bundles. A trench becomes tons of base.

Get the quantity wrong and every number downstream is wrong with it. The markup is right, the labor rate is right, and the bid still loses money because the takeoff was short.

So these are grouped by job, not by formula. Find the trade you are bidding, take the quantity, and move on. They are free, and none of them asks you to sign up first.

Concrete and masonry: the construction calculator set for site work

• Concrete Slab Cost Calculator

  Turns slab dimensions into cubic yards, bag counts and a delivered price. It orders 4 to 10 percent over plan, the range NRMCA CIP 31 publishes.

  Inputs: length, width, thickness, waste percentage

• Concrete Cubic Yard Calculator

  Answers the only question the batch plant asks: how many yards is the pour.

  Inputs: length, width, depth, shape

• Rebar Quantity Calculator

  Counts bars, lineal feet and weight for a slab mat, off the bar properties in the WSDOT Bridge Design Manual.

  Inputs: slab dimensions, bar spacing, bar size, lap length

• Gravel and Base Yardage Calculator

  Converts a pad or drive into cubic yards and tons of base. Wisconsin DOT 305.4 puts dense base at 1.85 tons a cubic yard.

  Inputs: area, compacted depth, aggregate type

• Concrete Driveway Cost

  Prices a full driveway: concrete, mesh, crew hours and haul-off of the old slab.

  Inputs: driveway size, thickness, reinforcement, removal

• Asphalt Driveway Cost Calculator

  Turns a drive into tons of hot mix and a price. Iowa DOT 2303 sets the unit weight at 145 pounds a cubic foot.

  Inputs: area, mat thickness, base depth, tack

Roofing, siding and gutters

• Roofing Squares Calculator

  Square feet to squares to bundles, using the coverage each maker publishes. A TAMKO Elite Glass-Seal square is 3 bundles over 100 square feet; an IKO Armourshake square is 5.

  Inputs: roof area, pitch, shingle line, ridge and starter

• Roof Replacement Cost

  Prices the whole re-roof: tear-off, underlayment, shingles and labor, per square and per job.

  Inputs: squares, shingle grade, existing layers, pitch

• Siding Squares Calculator

  Wall area to cartons of lap or vinyl. James Hardie publishes one SQ as 100 square feet of coverage less openings.

  Inputs: wall dimensions, openings, profile, exposure

• Gutter Installation Cost

  Gutter, downspout and guard priced by the foot, with a crew rate on top.

  Inputs: run length, downspout count, gutter size, guard

Paint and drywall

• Paint Coverage Calculator

  Square feet to gallons at the planning rate Sherwin-Williams publishes, about 350 to 400 square feet a gallon.

  Inputs: wall area, coats, doors and windows

• Paint Cost Calculator

  Gallons, coats and what the paint actually costs at the line you spec.

  Inputs: room size, coats, paint line, ceiling height

• Drywall Calculator

  Room size to sheets, mud, tape and screws. USG submittals put all-purpose compound at 10 gallons a 1,000 square feet.

  Inputs: room dimensions, ceiling height, sheet length, finish level

• Insulation Calculator

  Area and target R-value to bags of blown fill or bundles of batts.

  Inputs: area, insulation type, cavity depth, R-value

• Framing Calculator

  Wall length to studs, plates, headers and a cut list, at 16 or 24 in on center.

  Inputs: wall length, height, spacing, openings, corners

SimplyWise Cost Estimator turns a photo into an itemized, branded estimate in about 6 seconds, with material, labor and fee lines broken out.

Flooring and tile

• Flooring Calculator, Square Feet to Boxes

  Boxes to order with the cutting allowance in. Bruce installation instructions call for 5 percent straight and 10 percent on a diagonal.

  Inputs: room area, carton coverage, layout, grade

• Flooring Cost Calculator

  Material cost by flooring type, from laminate through solid hardwood.

  Inputs: area, material, waste percentage, underlayment

• Tile Material Calculator

  Square feet to boxes of tile, with the cuts and the pattern accounted for.

  Inputs: area, tile size, pattern, waste percentage

Decks, fencing and landscaping

• Deck Material Calculator

  Joists, beams, boards, fasteners and railing off one deck size, run against the span tables in American Wood Council DCA 6.

  Inputs: deck size, joist spacing, board width, height

• Paver Calculator

  Patio size to pavers, base gravel and bedding sand, with the waste in.

  Inputs: area, paver size, joint, base and sand depth

• Retaining Wall Calculator

  Wall length and height to blocks, caps, base gravel and drainage stone, with the buried course and waste in.

  Inputs: wall length, exposed height, block size, waste

• Stair Calculator

  Total rise to riser count, riser height, run and stringer length, checked against the IRC stair limits.

  Inputs: total rise, riser target, tread depth, width

• Fence Cost Calculator

  Posts, panels, concrete and the price for a run of fence.

  Inputs: run length, post spacing, height, material

• Mulch Calculator

  Cubic yards, bags and cost for a bed. Clemson Extension puts one cubic yard over 324 square feet at an inch deep.

  Inputs: bed area, depth, bulk or bagged, delivery

Plumbing, electrical and septic

• Plumber Hourly Rate

  Builds a billable hour from the published wage up, through burden, overhead and margin. The BLS OEWS code is 47-2152.

  Inputs: wage percentile, burden, overhead, target margin

• Electrical Panel Upgrade Cost

  Prices a 100, 150 or 200 amp service change, panel and breakers and permit included.

  Inputs: service size, panel model, breaker count, permit fee

• Septic System Cost

  Tank, drainfield and permit, sized off the trench tables in the Virginia code at 12VAC5-610.

  Inputs: bedrooms, soil class, trench length, stone depth

Hauling and site cleanup

• Dumpster Rental Prices by Size

  Which box the debris fits, what the weight limit is, and what the haul runs.

  Inputs: debris volume, material, rental days, tonnage

• Junk Removal Cost by Load Size

  What to charge by load fraction, with the dump fee carried through.

  Inputs: load fraction, material weight, dump fee, drive time

How to run a takeoff with a construction calculator

The order matters, because every construction calculator on this page answers one line and hands the next one to you. Run them in this sequence and the bid adds up.

1. Measure once, in the units the material sells in

   Concrete sells by the yard, shingles by the square, drywall by the sheet. Take the field measurement in feet and let the calculator do the conversion.

2. Add the waste the maker publishes, not a habit

   NRMCA says order 4 to 10 percent over plan on concrete. Bruce says 5 percent straight and 10 percent diagonal on wood floors. Those numbers are printed. Use them.

3. Price the quantity at your supplier, not a national mean

   Every price on these pages carries a capture date and a seller. Treat it as a sanity check on your own quote, never as your quote.

4. Put crew hours on a loaded rate

   A published wage is not a billable hour. Run it through burden, overhead and margin before it touches the bid.