Construction Calculators
Materials, areas, volumes and site quantities for building work.
- 3-Phase Power Calculator Calculate three-phase power in kW, kVA and kVAR from voltage, current and power factor, or the current drawn by a three-phase load.
- Aggregate Calculator Convert an amount of gravel, sand, stone or other aggregate between cubic yards, US tons, cubic metres and tonnes using its typical density.
- Asphalt Millings Calculator Work out the tons of recycled asphalt millings for a driveway or lot from the compacted depth, and compare the cost with new hot-mix asphalt.
- Asphalt Tonnage Calculator Work out how many tons of hot-mix asphalt you need from the area and compacted thickness, with the spread rate, truckloads and material cost.
- Barndominium Cost Calculator Estimate the cost to build a barndominium from the living area, shop space, finish level and site work, with the total and cost per square foot.
- Baseboard Calculator How many lengths of baseboard or skirting to buy for a room, from its perimeter less the doors, with corners and finishing nails counted.
- Bathroom Remodel Calculator Estimate the cost of a bathroom remodel from its size and finish level, with plumbing changes, a contingency and the typical labour share.
- Blacktop Calculator Estimate the cost of a blacktop driveway or pad, adding the asphalt, the stone base and labour, with the total and the price per square foot.
- Block Calculator Concrete blocks for a wall from its area less openings, counted with their mortar joints, with courses and total weight — UK blocks or US CMU.
- Block Wall Calculator Lay out a concrete block wall course by course: courses, full and half blocks for running bond, cap blocks, mortar bags and footing concrete.
- Brick Calculator Bricks for a wall from its area less openings, counting the mortar joint each brick includes — the detail that turns 72 bricks per square metre into 60.
- Carpet Calculator How much carpet to buy from a 4 m, 5 m or 12 ft roll, laying it the way that wastes least, with seams, trim allowance and cost.
- Ceiling Tiles Calculator Work out the tiles and grid for a drop ceiling: 2×2 or 2×4 tiles, main tees, cross tees, wall angle and hanger wires for your room.
- Cinder Block Wall Calculator Count the cinder blocks for a wall, with openings and waste, and get the total weight, pallets to order and the cost of the blocks.
- Concrete Block Wall Calculator Work out the grout and rebar for a reinforced 8 in concrete block wall: grouted cells or solid grouting, bond beam and the bars to order.
- Concrete Calculator Concrete for slabs, columns and steps in cubic yards or cubic metres, with the ready-mix order to place and the number of premix bags as an alternative.
- Concrete Footing Calculator Concrete for strip footings under walls or pad footings under posts, with the order, bags, and proportions checked against common rules of thumb.
- Concrete Slab Calculator Concrete for a slab from its size and thickness, with waste, the ready-mix order, bags, optional cost, and what an extra inch of thickness would add.
- Countertop Square Footage Calculator Add up countertop square footage for up to three sections, including an island and backsplash, with the cost and number of stone slabs.
- Crushed Concrete Calculator Work out the tons of recycled crushed concrete for a base or driveway and compare its cost with virgin crushed stone for the same area.
- Crusher Run Calculator Work out the tons of crusher run for a compacted base, allowing for compaction, with the loose depth to spread and the number of lifts.
- Deck Board Calculator How many deck boards to buy, rows across the deck, and screws or hidden clips, from the deck size, board width, gap and length.
- Deck Calculator Framing take-off for a deck: joists, hangers, ledger, rim, beam, posts and footing concrete, from the deck size and spacings.
- Deck Footing Calculator Size deck footings from the load each post carries and the soil bearing capacity, with the concrete volume and bags for every footing.
- Deck Joist Calculator Count the deck joists you need for a given deck length and spacing, and check the joist span against IRC limits for 2×6 to 2×12 lumber.
- Deck Post Spacing Calculator Work out how many deck posts each beam needs and how far apart to set them, with cantilever checks and the total post count.
- Dirt Calculator Find how many cubic yards of dirt you need for an area and depth, with the weight, dump-truck loads and the delivered cost.
- Dirt Volume Calculator Find the volume of dirt in a pit, round hole, trench, cone-shaped pile or berm, in bank yards and loose yards after digging.
- Drywall Calculator Sheets of drywall or plasterboard for a room's walls and ceiling, less openings, with waste, screws and how many sheets other sizes would take.
- Electrical Load Calculator Estimate a home's electrical load and service size with the NEC 220.82 optional method: floor area, appliances and heating or cooling.
- Excavation Calculator Soil to dig out for a foundation, pond or trench: in-ground volume, loose volume after swell, truckloads or skips, weight and removal cost.
- Fault Current Calculator Estimate available short-circuit current at a transformer and at the end of a conductor run using the point-to-point method.
- Fence Calculator Posts, rails, boards and post-hole concrete for a wooden fence, from its length, height, post spacing, gates and board size.
- Fence Post Depth Calculator Find how deep to set fence posts from the fence height, frost depth, post type and soil, with the hole size and the post length to buy.
- Fill Dirt Calculator Work out how much loose fill dirt to order to raise the ground by a compacted height, allowing for shrinkage, with truckloads and lifts.
- Flooring Calculator Boxes of wood, vinyl or laminate flooring for a room — including L-shaped rooms — with waste set by the laying pattern and underlay rolls.
- Friction Loss Calculator Calculate water friction loss in a pipe with the Hazen–Williams formula from flow, inside diameter, length and pipe material, with head and velocity.
- Gravel Calculator Gravel for a path, driveway or border from its size and depth: tons or tonnes, cubic yards or m³, bags, bulk bags and optional cost.
- Grout Calculator Grout for a tiled area from the tile size, thickness and joint width, using the manufacturers' formula — and why small tiles use so much more.
- Gutter Fall Calculator Check an existing gutter from its measured fall: slope per 10 ft, percent and degrees, whether it drains properly and the drop it should have.
- Gutter Installation Cost Calculator Estimate the cost of installing gutters by material and length, with downspouts, gutter guards and removal of old gutters.
- Gutter Slope Calculator Set out the drop for a new gutter run: total fall at your chosen slope, chalk-line layout, split runs over 40 ft and the number of hangers.
- Hardwood Floor Calculator Cartons of solid hardwood flooring with waste set by grade and pattern, plus a moisture check between the boards and the subfloor.
- Heat Pump Cost Calculator Estimate the size and installed cost of a heat pump from your home's area and system type, with rebates and payback against a conventional system.
- Home Addition Cost Calculator Estimate the cost of a home addition from its size and type, a room addition, second storey, sunroom or garage, with design, permits and contingency.
- Insulation Calculator How thick insulation must be to reach a target R-value, in US or SI units, for common materials, with the amount to buy and the resulting U-value.
- Laminate Flooring Calculator Planks and packs of laminate for a room, plus a row plan that shows how wide the last row will be and when to rip the first row.
- Landscape Material Calculator Get quantities of mulch, topsoil, compost, decorative gravel and paver sand for one area at once, in cubic yards, tons and retail bags.
- Limestone Calculator Work out how many tons of crushed limestone you need by grade, #57, #411, #3 or screenings, with truckloads and cost for driveways and bases.
- LVL Span Calculator Estimate how far a 1¾ in LVL beam can span for its depth, number of plies and the floor load it carries, with bending, shear and deflection checks.
- Material Calculator Work out the volume and weight of any bulk material, from gravel and sand to mulch and concrete, for an area and depth, or with your own density.
- Mortar Calculator Mortar for brick or block walls from the wall area, with the cement bags and sand to buy at your mix ratio — allowing for dry materials shrinking when mixed.
- Mulch Calculator Mulch for beds and borders from the area and depth: cubic yards or m³ with settling, bags, bulk bags, coverage and optional cost.
- Paint Calculator Paint for a room's walls and ceiling from its size, coats and the paint's coverage, rounded to the cans you can actually buy.
- Pavement Calculator Find how far a load of asphalt will pave at your width and thickness, using the spread rate in pounds per square yard, and the yield per ton.
- Pea Gravel Calculator Work out how much pea gravel you need and whether buying 0.5 cubic foot bags or a bulk delivery by the ton is cheaper for your project.
- Plaster Calculator Bags of plaster for a wall or ceiling from the area, coat thickness and product coverage, for finish skims and undercoats alike.
- Pond Calculator Work out a garden pond's water volume in gallons, the pump size for your turnover time and the liner size from its dimensions and depth.
- Pond Size Calculator Work out how big a pond your koi or goldfish need: minimum gallons, surface area at your depth and pond dimensions to dig.
- Post Hole Concrete Calculator Concrete for fence and deck post holes, less the volume the post itself fills, in bags per hole and in total, with sizing rules of thumb.
- Primer Calculator Primer or a mist coat for a room from its size and the surface, which sets how far a litre goes — with the water to add for a mist coat on new plaster.
- Rafter Dimensions Calculator Work out rafter cut angles and birdsmouth dimensions from the pitch and rafter size: plumb and seat cuts, heel depth, height above plate and line length.
- Rafter Length Calculator Common rafter length from the building span, roof pitch, overhang and ridge board, with the stock length to buy and the plumb cut angle.
- Rebar Calculator Bars, total length, laps and weight for a reinforcing grid in a slab or footing, in US bar sizes or metric — with bars counted as spaces plus one.
- Recessed Lighting Calculator Work out how many recessed lights a room needs from its size, its use and the lumens of each fixture, with the total lumens and watts.
- Recessed Lighting Layout Calculator Lay out recessed lights in an even grid from the room size and ceiling height: rows, columns, spacing and the distance from each wall.
- Rip Rap Calculator Estimate the tons of rip rap stone to armour a bank or shoreline from its length, height and slope, with the layer thickness set by stone size.
- River Rock Calculator Find the tons of river rock for a landscape bed by stone size, with the right depth for each size, coverage per ton, bags and fabric.
- Rock Calculator Estimate the weight of a boulder or landscape rock from its size, shape and rock type, and see what equipment you need to move it.
- Roof Pitch Calculator Convert a roof’s rise and run, or its angle, into pitch in 12, degrees, percent grade and pitch factor, with what the slope suits.
- Roofing Calculator The area of a roof in square feet, square metres and roofing squares, from the building footprint, overhang and pitch, with waste by roof shape.
- Sand Calculator Sand for paver bedding, a pool base or a sandpit from the area and depth: tons or tonnes, cubic yards or m³, bags and optional cost.
- Septic System Size Calculator Size a septic drain field from bedrooms and the perc test rate: absorption area in square feet, trench length and the number of trenches.
- Septic Tank Size Calculator Find the septic tank size you need in gallons from the number of bedrooms, with garbage disposal sizing and a pumping interval estimate.
- Shingle Calculator Bundles of asphalt shingles for a roof, plus hip and ridge cap, starter strip and roofing nails, from the roof area and edge lengths.
- Soffit Calculator Work out the soffit panels and J-channel for your eaves, and how much vented soffit gives enough attic intake air under the 1/300 rule.
- Soil Yard Calculator Convert bags of soil to cubic yards or yards to bags for any bag size, and compare the cost of bagged soil with bulk soil by the yard.
- Spray Foam Insulation Calculator Work out the board feet of open-cell or closed-cell spray foam to reach a target R-value, with thickness, kits to buy and installed cost.
- Stair Calculator Number of risers and treads, riser height, total run, stringer length and angle for a straight stair, with a comfort and code check.
- Stud Calculator Studs and plates for a framed wall at 16 or 24 in or metric centres, counted as spaces plus one, with extras for corners and openings.
- Subcooling Calculator Calculate HVAC subcooling from liquid line pressure and temperature for R-410A, R-22 or R-134a, and compare it with the target charge.
- Superheat Calculator Calculate HVAC superheat from suction pressure and suction line temperature for R-410A, R-22 or R-134a, with a fixed-orifice target.
- Tile Calculator Tiles and boxes for a floor or wall from the area and tile size, counted with the grout joint and a waste allowance set by the layout pattern.
- Topsoil Calculator Topsoil for a lawn or garden bed from the area and depth: cubic yards or m³ with settling included, the weight, bags, bulk bags and optional cost.
- Wainscoting Calculator Work out the panels or boards for wainscoting around a room, less doors, with chair rail and baseboard trim, at a height you choose.
- Wallpaper Calculator Rolls of wallpaper for a room counted by full-height drops, with the pattern repeat included — the detail that area-based estimates miss.
- Well Drilling Cost Calculator Estimate the cost of drilling a water well from its depth and price per foot, with casing, pump system, permit and water testing.
- Wire Calculator Find the copper or aluminum wire size for a circuit from its amps, length and voltage, checking ampacity and keeping voltage drop within limits.
- Yards of Gravel Calculator Find how many cubic yards of gravel a rectangle, circle or triangle needs, with the order size, wheelbarrow loads and pickup trips.
A Guide to Construction Calculators
Every material calculator on a building site answers the same underlying question: how much do I buy so that I do not run out and do not throw money away. The arithmetic is volume or area divided by coverage. What makes these calculators worth using is everything around that division: the waste allowance, the units the supplier actually sells in, and the compaction or spread rate that turns a measured volume into a delivered quantity.
Eighty-nine calculators here, grouped by trade. All of them detect whether you are working in metric or imperial and report back in the same system, and all of them show their working, so you can check the figure against your own estimate before you order.
Concrete
Five calculators. The Concrete Calculator is the general one, with the Concrete Slab Calculator and Concrete Footing Calculator shaped around the two pours most jobs need. The Post Hole Concrete Calculator handles the annulus around a post, which is the case people most often get wrong by treating the hole as solid. The Rebar Calculator works out bar lengths and spacing, including the laps.
Concrete is sold by the cubic yard or cubic metre and delivered in whole loads, so these calculators report both the raw volume and what you will have to order.
Landscaping and aggregate
The largest group, at twenty-three calculators, because the material names are not interchangeable and the coverage rates differ. Gravel, Pea Gravel, Crusher Run, Crushed Concrete, Limestone, River Rock, Rip Rap, Rock, Sand and the general Aggregate and Landscape Material calculators each use the bulk density of that material rather than a single average, which is what makes the tonnage figure usable.
For soil there are Topsoil, Fill Dirt, Dirt, Dirt Volume and Soil Yard calculators, plus Excavation for material coming out rather than going in. Excavated soil bulks up when it is dug and compacts when it is placed, and the two directions do not cancel, which is why the calculator asks which you are doing.
Mulch is sold by volume and spread by depth, and the Asphalt Millings Calculator covers reclaimed material used as a surface. The Material Calculator is the catch-all when you know the density and want the arithmetic done.
Two calculators cover water features: Pond for volume and liner, and Pond Size for working the other way from a stocking or pump requirement. The Yards of Gravel Calculator exists because that is how the question is usually phrased to a supplier.
Paving and asphalt
Asphalt Tonnage, Blacktop and Pavement calculators work from area and compacted depth. Asphalt is ordered by weight and laid by thickness, so the conversion depends on the mix density and the compaction factor, both of which the calculator states rather than hiding in a constant.
Masonry
Six calculators. Brick, Block, Block Wall, Cinder Block Wall and Concrete Block Wall calculators count units for a wall of given dimensions, allowing for the mortar joint, which is the difference between a figure that works and one that leaves you a course short. The Mortar Calculator gives the bedding material for that unit count.
Framing, walls and structures
The Stud Calculator spaces a wall, Drywall sheets it, and Insulation and Spray Foam Insulation fill it. The Plaster calculator covers the wet finish.
For structures, the Deck Calculator and Deck Board Calculator size the surface, while Deck Joist, Deck Post Spacing and Deck Footing calculators handle what holds it up. The LVL Span Calculator covers engineered beams, and the Stair Calculator works out rise and run together, since changing one forces the other.
Fencing has three: Fence for materials, Fence Post Depth for how deep the posts have to go, and the post hole concrete calculator above for setting them.
Roofing and rainwater
Eight calculators. The Roof Pitch Calculator is the one to start from, because pitch determines the true surface area, and a roof measured as a flat footprint is always undersized. From there, Roofing and Shingle calculators give the covering, Rafter Length and Rafter Dimensions the structure, and Soffit the eaves.
For rainwater, Gutter Slope and Gutter Fall calculators handle the drop along a run, which is the same quantity expressed two ways because both phrasings are in common use.
Flooring and finishes
For floors: Flooring, Tile, Hardwood Floor, Laminate Flooring and Carpet calculators, with Grout for the joints. Each applies a waste allowance appropriate to the material, because a tiled floor with a diagonal lay wastes far more than a carpet roll.
For surfaces and finishes: Paint and Primer calculators work from area and coverage per coat, and Wallpaper accounts for pattern repeat, which can change the roll count substantially. Ceiling Tiles, Wainscoting, Baseboard and Countertop Square Footage cover the remaining measured items.
Electrical
Six calculators. The Electrical Load Calculator totals demand, the Wire Calculator sizes the conductor for that load and run length, and the Fault Current Calculator gives the figure protective devices are rated against. The 3-Phase Power Calculator handles the three-phase relations, where the factor of root three is the usual source of error.
For lighting, Recessed Lighting gives the fitting count and Recessed Lighting Layout the spacing, including the smaller offset from the walls that keeps the edges of a room from going dark.
Plumbing, HVAC and septic
The Friction Loss Calculator gives pressure loss along a pipe run, which is what decides pump sizing.
For refrigeration, the Superheat Calculator and Subcooling Calculator are the two measurements used to judge a charge, and they diagnose opposite faults, so both are needed.
Septic Tank Size and Septic System Size calculators work from occupancy and daily flow against the minimums that regulations set.
Project costs
Six calculators for whole-job budgets rather than single materials: Bathroom Remodel, Home Addition, Barndominium, Heat Pump, Gutter Installation and Well Drilling.
These are the roughest figures on the site and they are presented as ranges for that reason. Labour rates vary by region far more than material prices do, and a cost calculator that returns a single number for a kitchen is giving false precision. Use them to sanity-check a quote, not to replace one.
The three mistakes that cost the most
Most ordering errors on a site are not arithmetic. They are one of three substitutions.
The first is measuring a sloped surface as a flat one. A roof, a ramp or a bank has a true area larger than its footprint, and the gap grows quickly: a 6-in-12 pitch is about twelve percent more surface than the plan area, and a 12-in-12 is forty-one percent more. This is why the roof pitch calculator comes before the shingle calculator rather than after it.
The second is confusing loose volume with compacted volume. Aggregate, soil and asphalt all occupy less space once placed and compacted than they did in the truck, and the factor is material-specific. Ordering the compacted volume leaves you short every time.
The third is treating a hollow shape as a solid one. A post hole with a post in it, a block wall with cores, a slab with a service void: each needs the displaced volume subtracted, and on small jobs that subtraction is a large fraction of the total.
A word on waste and ordering
The quantity you need and the quantity you buy are different numbers. Sheet goods come in fixed sizes, concrete in whole loads, aggregate in whole tons, paint in fixed tin sizes. Every calculator here reports the measured requirement and the practical order quantity separately, so you can see how much of the difference is waste allowance and how much is just the supplier's unit.
Measure twice. A one percent error in a length becomes a two percent error in an area and a three percent error in a volume, which on a concrete pour is the difference between one load and two.