Engineering & build calculators
Gears, torque, concrete, roofs and the quantities you have to order before you start.
Spur Gear GeneratortoolInvolute spur gears from module and tooth count — download SVG or DXF.Finger Joint Box GeneratortoolLaser-cut boxes with finger joints — enter three dimensions, download the cut file.Bolt Circle GeneratortoolHole positions on a pitch circle, with coordinates and a cut file.Gear Ratio CalculatorRatio, output speed and torque multiplication for a gear pair or train.Torque CalculatorTorque from force and radius, converted between every common unit.Pulley & Belt CalculatorDriven speed, ratio and belt length for a two-pulley drive.Kinetic & Potential Energy CalculatorEnergy and momentum of a moving or raised mass.Projectile Motion CalculatorRange, peak height and flight time for a launch angle and speed.Concrete CalculatorVolume of concrete for a slab, footing or column, and bags needed.Roof Pitch CalculatorPitch, angle, rafter length and the area multiplier.Paint CalculatorHow much paint a room needs, after doors, windows and coats.Board Foot CalculatorBoard feet and cost for rough lumber.Tile & Flooring CalculatorTiles, boxes and adhesive for a floor or wall.Electricity Cost CalculatorWhat an appliance costs to run, per day, month and year.BTU & Air Conditioner Size CalculatorCooling capacity a room needs, adjusted for the things that matter.Molarity & Dilution CalculatorConcentration, mass needed, and the dilution equation.Ideal Gas Law CalculatorSolve PV = nRT for whichever term you are missing.Tap Drill & Thread Size CalculatorTap drill size, clearance hole and thread engagement for metric and unified threads.Cutting Speed, RPM & Feed Rate CalculatorSpindle speed and feed from surface speed and chip load — milling, turning, drilling.Sheet Metal Bend Allowance CalculatorBend allowance, bend deduction and flat pattern length from the K-factor.Bolt Torque CalculatorTightening torque from size, grade and lubrication — with the preload it produces.Beam Deflection CalculatorMaximum deflection, moment and bending stress for the standard load cases.Section Modulus & Moment of Inertia CalculatorArea, I, section modulus and weight per metre for the common structural shapes.Stress, Strain & Elongation CalculatorAxial stress, strain, extension and safety factor from load and section.Belt Length & Pulley CalculatorBelt length, wrap angle and centre distance for open and crossed drives.Compression Spring CalculatorSpring rate, shear stress and solid height from wire size and coil geometry.Hydraulic Cylinder Force CalculatorPush and pull force, speed and flow demand from bore, rod and pressure.Pipe Flow & Pressure Drop CalculatorVelocity, Reynolds number and friction pressure loss in a round pipe.Pump Power CalculatorHydraulic power, shaft power, motor size and running cost from flow and head.Thermal Expansion CalculatorLength change with temperature, and the stress if the part cannot move.Bearing Life CalculatorL10 life in revolutions and hours from dynamic capacity, load and speed.Stair CalculatorRiser height, tread depth, stringer length and the code checks, from total rise.Rebar CalculatorBar count, total length, weight and laps for a slab or footing mat.Tank Volume CalculatorTotal and filled volume for cylindrical, rectangular and spherical tanks.Drywall CalculatorSheets, screws, tape and compound for a room, minus the openings.Gravel, Soil & Mulch CalculatorVolume, weight and bag count for any loose material spread to a depth.Wall Framing CalculatorStuds, plates, headers and noggins for a timber-framed wall.