Electricity Calculator

  • Watts to BTU/hr Calculator
    Convert watts (W) to BTU per hour instantly. Enter power in watts to get BTU/hr using the factor 1 W = 3.412142 BTU/hr. Free and accurate.
  • Electricity Savings Calculator
    Calculate how much money and energy you save by switching to lower-wattage appliances or bulbs. Estimate daily, monthly and annual electricity savings.
  • BTU/hr to Watts Calculator
    Convert BTU/hr to watts instantly. Enter power in BTU per hour and get the equivalent in watts and kilowatts using W = BTU/hr ÷ 3.412.
  • kWh to kW Calculator
    Convert energy in kilowatt-hours (kWh) to power in kilowatts (kW) by dividing energy by time in hours. Fast, accurate kWh to kW conversion.
  • Running Amps and Startup Load Calculator
    Size a generator by adding running watts plus the largest startup surge. Enter your appliances to find the minimum wattage and a recommended size.
  • Cost to Run a Device per Hour Calculator
    Calculate the electricity cost to run any device per hour from its wattage and your kWh rate. Also shows daily, monthly and yearly running costs.
  • Solar Battery Bank Size Calculator
    Calculate the battery bank size in amp-hours (Ah) for your solar/off-grid system from daily energy use, days of autonomy, voltage and depth of discharge.
  • Wire Gauge (AWG) Calculator
    Convert American Wire Gauge (AWG) to conductor diameter and cross-sectional area, and estimate copper wire current capacity (ampacity) by density.
  • VinFast Charging Time From % to % Calculator
    Estimate how long your VinFast EV takes to charge from one battery percentage to another based on battery size, charger power, and charging efficiency.
  • VinFast Charging Speed (Miles Added per Hour) Calculator
    Estimate how many miles of range your VinFast EV gains per hour of charging from charger power, efficiency, battery size, and EPA range.
  • Watts to Amps Calculator
    Convert watts to amps instantly. Enter power in watts and voltage to find the current in amps using amps = watts ÷ volts. Free DC power calculator.
  • Photon Energy Calculator
    Calculate photon energy from wavelength or frequency using E = hf = hc/λ. Get results in joules, electronvolts, frequency (THz) and wavelength (nm).
  • Watts to kVA Calculator
    Convert watts (W) to kilovolt-amps (kVA) using the power factor. Fast, accurate W to kVA conversion for AC electrical systems.
  • Solar Panel Tilt Angle Calculator
    Find the optimal solar panel tilt angle from your latitude. Get year-round, summer, and winter tilt settings to maximize energy production.
  • Solar Charge Controller Sizing Calculator
    Size your solar charge controller in amps from panel wattage and battery voltage. Includes a 1.25 safety factor for MPPT/PWM controller selection.
  • Series/Parallel Battery Pack Calculator
    Calculate battery pack voltage, capacity (Ah) and energy (Wh) from cell specs and your series/parallel (SxP) configuration. Free, instant results.
  • Impedance Calculator (Z from R and X)
    Calculate AC impedance Z from resistance R and reactance X using Z = √(R² + X²). Also returns the phase angle θ in degrees instantly.
  • kW to HP Calculator
    Convert kilowatts (kW) to mechanical horsepower (hp) instantly. Uses HP = kW / 0.7457 for accurate power conversion of engines and motors.
  • HP to kW Calculator
    Convert horsepower (HP) to kilowatts (kW) instantly. Enter any HP value to get the equivalent power in kW using kW = HP × 0.7457.
  • kVA to kW Calculator
    Convert apparent power (kVA) to real power (kW) using the power factor. Free kVA to kW calculator with reactive power (kVAR) output.
  • Power Dissipation in a Resistor Calculator
    Calculate the power dissipated by a resistor using P = I²·R or P = V²/R. Enter current and resistance, or voltage and resistance, to get watts instantly.
  • Appliance Run Time Battery Calculator
    Estimate how long a battery will power an appliance from its Ah capacity, voltage, load watts and system efficiency. Free runtime calculator.
  • Motor Power Calculator
    Calculate mechanical motor power from torque and RPM. P = T × 2π·RPM/60, with instant output in watts, kilowatts and horsepower.
  • Energy Cost Per Hour Calculator
    Calculate the electricity cost per hour of any appliance from its wattage and your kWh rate. See hourly, daily, monthly and yearly running costs instantly.

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