Engineering & Electrical calculators
Ohm's law, voltage drop, wire gauge, power, resistors and HVAC.
50 free tools
Most used
Bolt Torque CalculatorTightening torque and clamp load for inch and metric bolts by gradeBTU CalculatorFind the air conditioner or heater BTU size your room needsMetal Weight CalculatorWeigh steel, aluminum, stainless, brass and more by shape and sizeOhm's Law CalculatorSolve voltage, current, resistance and power from any two valuesResistor Color Code CalculatorDecode 4, 5 and 6-band resistors — or find the colors for any valueReynolds Number CalculatorFind the Reynolds number and whether flow is laminar or turbulentSpeeds and Feeds CalculatorSpindle RPM, feed rate and metal removal for milling, drilling, turningStress & Strain CalculatorGet stress, strain and Young's modulus for a bar under axial loadVoltage Drop CalculatorCheck voltage drop and power loss over any wire runWatts, Amps and Volts CalculatorConvert watts to amps, amps to watts, or find volts for DC and ACWire Size CalculatorFind the right AWG wire gauge for your load, distance and voltage
More engineering & electrical tools
Air Changes per Hour CalculatorTurn fan or purifier airflow and room size into air changes per hourArea Moment of Inertia CalculatorSecond moment of area, section modulus and centroid for beam sectionsBattery Life CalculatorEstimate how long a battery will last from capacity and loadBelt Length CalculatorBelt length, wrap angle and speed ratio for a two-pulley driveCFM CalculatorWork out the airflow (CFM) a room or exhaust fan needsCircuit Breaker Size CalculatorFind the right breaker size for a load using the 80% continuous ruleCoil Spring Rate CalculatorCompression spring rate, load, stress and solid height from dimensionsConduit Fill CalculatorCheck NEC conduit fill % and how many wires fit in EMT or PVCFactor of Safety CalculatorFactor of safety, margin of safety and allowable load from strength and loadFillet Weld CalculatorFind fillet weld throat, area and design strength (AISC LRFD or ASD)Gear Ratio CalculatorGet gear ratio, output RPM and output torque from tooth countsGenerator Size CalculatorFind the generator wattage you need from running and starting wattsHoop Stress CalculatorHoop and longitudinal stress in pipes, tanks and pressure vesselsHorsepower CalculatorConvert torque and RPM to horsepower and kW — or solve for torque or RPMHydraulic Cylinder CalculatorPush and pull force, rod speed, oil volume and cycle time for any cylinderkVA and Transformer Size CalculatorConvert kVA to amps (or amps to kVA) and pick a standard transformer sizeLED Resistor CalculatorFind the right current-limiting resistor and wattage for any LEDMotor Full Load Amps CalculatorLook up NEC full-load current for single- and three-phase AC motorsPipe Flow Rate CalculatorFind pipe flow in GPM or L/min from diameter and velocity — or the reversePipe Pressure Drop CalculatorFriction loss in pipes by Darcy-Weisbach (Colebrook) or Hazen-WilliamsPulley Speed CalculatorFind driven pulley RPM, the pulley size you need, ratio and belt speedPump Power CalculatorHydraulic, brake and motor power for a pump — plus yearly energy costSeries and Parallel Resistor CalculatorTotal resistance of any resistors in parallel and in series, instantlySheet Metal Bend Allowance CalculatorBend allowance, bend deduction and flat blank length for sheet metalThread CalculatorTap drill size, pitch diameter and minor diameter for metric and UNC/UNFThree-Phase Power CalculatorConvert between kW, kVA, amps and volts for balanced three-phase loadsTorque Wrench Extension CalculatorCorrect torque wrench setting when using a crowfoot or adapterViscosity CalculatorConvert dynamic viscosity to kinematic viscosity and back using densityVoltage Divider CalculatorFind Vout or the resistor you need for any two-resistor dividerBeam Deflection CalculatorMax deflection, bending moment and stress for common beam casesBearing Life CalculatorL10 rating life of ball and roller bearings in revolutions and hoursCapacitor CalculatorSeries and parallel capacitance, charge, energy and code decodingColumn Buckling CalculatorEuler critical buckling load, slenderness and Johnson check for columnsDecibel CalculatorConvert power or voltage ratios to dB and add sound levels correctlyDuct Size CalculatorSize round and rectangular HVAC ducts from airflow and velocityLMTD CalculatorLog mean temperature difference and heat exchanger area in one stepOrifice Flow CalculatorLiquid flow rate through an orifice, nozzle or hole from pressure or headPower Factor CalculatorFind power factor, kVA and kvar, and size a correction capacitorRC Time Constant CalculatorTime constant, charge/discharge curve and cutoff frequency of an RC circuit