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Construction & Home

Free construction calculators: concrete, paint, flooring, tile, roofing, drywall, mulch, gravel, sod, BTU, insulation, deck, fence and stairs — with waste factored in.

35 calculators Free and online

📌 About Construction & Home

Buying the right amount of material is the difference between one trip to the store and three — or a half-finished project and a pile of leftovers. These calculators turn your room or yard dimensions into exactly how much to buy: bags of concrete, gallons of paint, boxes of flooring, squares of shingles, cubic yards of mulch, and more, always rounded up to whole purchasable units with a waste factor built in.

Each tool uses the standard industry math and real material constants — an 80 lb concrete bag yields 0.6 cubic feet, a gallon of paint covers about 350 square feet, a roofing square is 100 square feet — and shows the breakdown so you can trust the number. Use them to estimate a DIY project, check a contractor's quote, or budget materials before you start.

  • Concrete, brick and asphalt by bags, cubic yards or tons
  • Paint, drywall and wallpaper by gallons, sheets and rolls
  • Flooring and tile by boxes and individual tiles, with waste
  • Roofing in squares and shingle bundles, adjusted for roof pitch
  • Mulch, gravel, topsoil and sod for any landscaping job
  • BTU sizing for heating and cooling, plus insulation, decks, fences and stairs

🧮 Calculators in this category

Concrete & Masonry

Asphalt Calculator — Hot-Mix Blacktop Tonnage by Area & Depth
Estimate how many tons of hot-mix asphalt a driveway, lot or road patch needs from its length, width and paving depth — plus cubic yards, waste and total cost.
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Brick Calculator — How Many Bricks per Square Foot & Mortar Bags
Enter a wall's length and height to find how many bricks you need, the bricks per square foot for your brick size, mortar bags, and a rounded-up purchase quantity with a waste allowance.
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Concrete Block Calculator — How Many Cinder Blocks for a Wall
Find how many concrete (cinder) blocks and bags of mortar you need to build a wall — enter length and height in feet and get the exact whole-block count to buy.
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Rebar Calculator — Linear Feet, Spacing & Number of Bars for a Slab
Lay out a rebar grid in seconds — find how many bars run each way, the total linear feet of steel, and the number of 20 ft sticks to buy, with lap-splice waste built in.
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Concrete Calculator — How Many Bags or Yards of Concrete
Find how much concrete you need for a slab, footing or round column — in cubic feet, cubic yards and the exact number of 40, 60 or 80 lb bags to buy.
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HVAC & Insulation

BTU Calculator — What Size AC or Heater Do I Need?
Size an air conditioner or heater for any room. Enter the square footage, sun exposure, number of people and your climate zone to get the cooling and heating BTU you need.
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Insulation Calculator — Batt Rolls & Blown-In Bags by R-Value
Measure a space, pick a target R-value, and get the exact number of batt rolls or blown-in bags to buy — rounded up — plus the fill depth and a waste allowance.
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Lumber & Framing

Deck Calculator — Decking Boards, Joists & Material Estimate
Enter your deck length and width to get the deck area, the number of decking boards (with a 1/8 in gap and waste allowance) and the joist count at 16 in on-center.
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Stair Calculator — Rise, Run, Risers, Treads & Stringer Length
Enter your total rise and this stair calculator returns the number of risers, the exact riser height, the number of treads, total run and the stringer length you need to cut — all checked against IRC stair code.
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Plywood Calculator — How Many Sheets of Plywood or OSB
Find how many sheets of plywood, OSB or sheathing you need for a subfloor, wall or roof — total square footage, sheets at 4x8 or 4x10, and the rounded-up count to buy.
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Baseboard Calculator — How Much Baseboard, Trim & Molding You Need
Find how much baseboard, trim or molding you need for a room — linear feet after subtracting doorways, plus the exact number of 16 ft or 8 ft pieces to buy.
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Board Foot Calculator — Lumber Volume & Cost
Find the board feet in any piece of lumber from its thickness, width and length — then multiply by quantity and price the whole lot at a price per board foot.
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Rafter Calculator — Rafter Length, Run, Rise & Total with Overhang
Find rafter length from your building span and roof pitch — run, rise, line length and total length with overhang, plus how many rafters and what board length to buy.
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Stud Calculator — How Many Studs for a Wall (16 or 24 in OC)
Find how many wall studs you need at 16 or 24 inch on-center spacing — plus plate lumber in linear feet — with extra studs added for corners and door/window openings, rounded up and with a waste factor.
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Paint & Walls

Drywall Calculator — Sheets, Mud, Screws & Tape Needed
Enter your wall and ceiling square footage to find how many drywall sheets you need, plus joint compound, screws and tape — all rounded up to whole purchasable units with a waste factor built in.
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Paint Calculator — How Much Paint Do I Need (Gallons)
Find out how many gallons of paint you need for a room. Enter the perimeter or wall dimensions, ceiling height, and how many doors and windows to subtract — get a rounded-up gallon count for 1 or 2 coats.
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Wallpaper Calculator — How Many Rolls of Wallpaper Do I Need?
Find out how many rolls of wallpaper to buy from your wall perimeter and ceiling height — with a pattern-repeat waste allowance and a rounded-up purchase count.
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Roofing & Exterior

Fence Calculator — Posts, Rails & Pickets for Any Yard
Enter the total length of your fence line and get the exact number of posts, rails and pickets to buy — rounded up to whole units with a waste allowance built in.
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Roof Pitch Calculator — Pitch, Slope Angle & Area Multiplier
Turn rise and run into roof pitch (x/12), the slope angle in degrees, and the roof-area multiplier that scales your flat footprint up to the true sloped surface.
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Roofing Calculator — Shingle Bundles & Roofing Squares
Enter your roof's footprint length and width plus the pitch, and get the roof area, the number of roofing squares, and how many shingle bundles to buy — waste included and rounded up.
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Siding Calculator — How Many Squares of Siding You Need
Find how much siding you need for a house or wall — net wall square footage minus doors and windows, plus the exact number of siding squares to order with waste.
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Flooring & Tile

Flooring Calculator — Laminate, Hardwood & Vinyl Boxes Needed
Enter your room's length and width to get the floor area, add a waste factor, and find out exactly how many boxes of laminate, vinyl plank or hardwood you need to buy.
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Tile Calculator — How Many Tiles & Boxes You Need
Enter your floor or wall size and the tile dimensions to get exactly how many tiles — and boxes — to buy, including a waste allowance for cuts.
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Carpet Calculator — How Many Square Yards of Carpet You Need
Find how much carpet you need for one or more rooms — in square feet and square yards — plus a waste allowance for seams and the 12-foot roll width, and the cost.
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Grout Calculator — How Much Grout for Tile (lbs & Bags)
Estimate how much tile grout you need — in pounds and whole bags — from your tile size, grout-joint width, joint depth and the square footage you're tiling.
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Landscaping & Garden

Gravel Calculator — Cubic Yards & Tons of Crushed Stone
Find how much gravel or crushed stone you need in cubic yards and tons for a driveway, walkway or drainage bed — from length, width and depth — with a waste allowance and total cost.
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Mulch Calculator — Cubic Yards & Bags of Mulch You Need
Figure out how much mulch to buy for a flower bed or garden — in cubic yards for bulk delivery, or in 2-cubic-foot bags — for any depth, then estimate the cost.
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Sod Calculator — Rolls, Pallets & Cost for a New Lawn
Measure your lawn in feet, add a waste allowance, and get the exact number of sod rolls and pallets to order — plus the total cost — so you don't come up short on grass.
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Topsoil Calculator — Cubic Yards & 40 lb Bags of Dirt
Find how much topsoil you need for a garden bed or lawn: cubic yards for a bulk delivery and the number of 40 lb bags for a smaller job, with the cost.
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Sand Calculator — Cubic Yards, Tons & Bags of Sand You Need
Figure out how much sand to buy for a paver base, sandbox, fill or leveling layer — in cubic yards and tons for bulk delivery, or in 50 lb bags — at any depth, then estimate cost.
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Hardscaping

Retaining Wall Calculator — How Many Blocks for a Retaining Wall
Find how many retaining wall blocks you need by wall length and height — including the buried base course, the cap row, the number of courses, and a waste factor.
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Paver Calculator — How Many Pavers for a Patio or Walkway
Find how many pavers you need for a patio, walkway or driveway — enter the area and paver size, add a waste factor, and get the exact number of pavers to buy.
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Site Work

Excavation Calculator — Cubic Yards of Dirt & Truckloads to Haul
Find how much dirt you'll dig out — bank cubic yards, the swelled loose volume after a swell factor, and how many dump truck loads it takes to haul away.
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Accessibility

Wheelchair Ramp Calculator — ADA Ramp Length & Slope
Find how long a wheelchair ramp must be for a given rise — ramp length, slope percentage and how many level landings you need, using the ADA 1:12 maximum slope.
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Area & Measurement

Square Footage Calculator — Area in Sq Ft, Sq Yards & Acres
Find the area of a room or lot in square feet, square yards and acres — then multiply by a price per sq ft to get the total cost for flooring, paint or carpet.
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FHA vs Conventional vs VA Loan: Which Fits?
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Hourly vs Salary: How to Compare Job Offers
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❓ Frequently asked questions

How much waste should I add to a material estimate?

A 10% waste factor is standard for most materials to cover cuts, breakage and mistakes; use 15–20% for diagonal flooring, complex tile patterns or irregular rooms. Every calculator here lets you set the waste percentage.

How many bags of concrete do I need?

Find the volume in cubic feet (length × width × thickness in feet), then divide by the bag yield: an 80 lb bag makes 0.60 cu ft, a 60 lb bag 0.45, and a 40 lb bag 0.30. The concrete calculator does this and rounds up.

How much paint do I need for a room?

Calculate the wall area (perimeter × ceiling height, minus doors and windows), multiply by the number of coats, and divide by ~350 sq ft per gallon. A typical 12×12 room needs about 2 gallons for two coats.

What size air conditioner or heater do I need?

Cooling needs roughly 20 BTU per square foot as a baseline, adjusted for sun, occupants and kitchens; heating runs 30–60 BTU per square foot by climate zone. The BTU calculator sizes both from your room dimensions.