Home & Construction calculators
Free home and construction calculators: concrete yards and slab cost, paint, siding and Hardie plank, flooring, roofing shingles, roof pitch and replacement cost, insulation and blown-in R-value, cinder block, board feet, feet-inch-fraction math, NEC wire size, water line size and GPM, Sonotube concrete, bolt circle coordinates, cubic yards of dirt, gravel and mulch, asphalt tonnage, cords of firewood, renovation cost, cubic and linear feet, and weight per gallon.
Sonotube Concrete Calculator
How much concrete for a Sonotube or round column? Enter diameter, depth and count to get cubic yards and 40, 60 or 80 lb bags.
Bolt Circle Calculator
Get X-Y coordinates for every hole on a bolt circle from diameter, hole count and start angle, plus chord spacing between holes.
Water Line Size & GPM Calculator
Size PEX, copper or CPVC water lines from GPM or fixture units, convert GPM to ft/s, estimate pressure loss, and find pipe volume or GPM from a bucket test.
Wire Size Calculator (Amps to AWG)
Compute wire size from amps, conductor metal, temperature, continuous load and run length. Includes NEC 310.16 ampacity, voltage drop and a full AWG chart.
Weight per Gallon Calculator
How much does a gallon of water, diesel, gasoline, propane, milk or paint weigh? Convert any volume to pounds and kilograms.
Linear Feet Calculator
Convert inches, meters or square feet to linear feet, add up multiple pieces, and estimate cost per linear foot for boards, trim, fencing and countertops.
Cubic Feet Calculator (ft³)
Calculate cubic feet for a box, room, cylinder, sphere or cone from inches, feet, yards or meters, and convert to cubic yards, liters and gallons.
Current Divider Calculator (Parallel Resistors)
Split current across parallel resistors from total current or voltage: branch currents, % share, power and equivalent resistance (parallel resistor formula).
Renovation Cost Calculator: Bathroom, Kitchen, Lighting
Estimate bathroom, kitchen, flooring or lighting renovation costs from your own quotes: area, items and labor plus contingency, with Census median spending.
Cubic Yard Calculator: Dirt, Gravel & Mulch
Calculate cubic yards of mulch, gravel or soil, then get tons to order, bags and weight. Includes mulch and gravel yards-to-tons tables and concrete yard weight.
Asphalt Calculator (Tons of Hot Mix)
How many tons of asphalt do you need? Area × thickness to tons of hot mix, bitumen and millings, plus a driveway estimate priced from state DOT unit prices.
Cord of Wood Calculator
Convert any firewood stack to cords, face cords (ricks) and cubic feet. A cord is 4×4×8 ft = 128 ft³ (NIST). Plus weight per cord by species.
Paint Calculator: How Much Paint Do I Need?
How much paint do I need? Enter walls, doors, windows and coats to get gallons and quarts, plus how many square feet 1 or 5 gallons of paint covers.
Board Foot Calculator (Lumber Board Feet)
Calculate board feet from thickness, width and length. Build a lumber list with nominal or actual sizes, waste and price per board foot.
Concrete Calculator: Cubic Yards & Bags
How many yards of concrete do I need? Enter slab, footing or column size, or square feet and thickness, to get cubic yards, premix bags and weight.
Concrete Slab Cost Calculator
Estimate concrete slab cost from size, thickness and your price per cubic yard, with delivery, base, rebar and labor lines plus public DOT bid benchmarks per sq ft.
Siding Calculator: Squares, Hardie Planks & Cost
Figure siding for a house: wall and gable area minus openings, squares, Hardie plank count by exposure, J-channel and trim, and the cost to side a house.
Insulation Calculator: R-Value, Batts & Rolls
Find the recommended R-value for your climate zone and attic, walls or floor, then count batts or rolls for your area and stud spacing, with cost.
Blown-In Insulation Calculator
Estimate bags of blown-in fiberglass or cellulose for your attic and target R-value from bag label charts. Get installed and settled depth, bags and cost.
Cinder Block Calculator (CMU Blocks, Mortar & Fill)
How many cinder blocks for a wall? Count 8x8x16 CMU blocks, mortar bags and core-fill grout in cubic yards for fully or partially grouted walls.
Roofing Shingles Calculator: Squares & Bundles
How many bundles of shingles do I need? Enter the roof footprint and pitch, or roof area, to get squares, bundles, starter, ridge cap and underlayment.
Roof Replacement Cost Calculator
Estimate roof replacement cost from roof size, pitch and your price per square, with tear-off layers, dumpster and permit, plus 2025 national averages explained.
Roof Pitch Calculator: Slope Factor & Rafter Length
Calculate roof pitch from rise and run, convert it to degrees and percent, and get the roof slope factor and rafter length with overhang. Full pitch chart.
Flooring Calculator: Square Feet & Boxes
Calculate flooring square feet for one or more rooms, add waste for the layout, and get boxes of laminate, vinyl plank, hardwood or tile, plus cost.
Construction Calculator: Feet, Inches & Fractions
Free online construction calculator: add, subtract, multiply and divide feet, inches and fractions, then convert to decimal feet, metric, area or volume.