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.
  • 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.
  • Watt-hour Calculator
    Calculate energy in watt-hours (Wh) and kilowatt-hours (kWh) from power in watts and run time in hours. Free, instant Wh = P × t calculator.
  • 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.
  • Smart Thermostat Savings Calculator
    Estimate how much money a smart thermostat can save you each year on heating and cooling. Enter your annual energy cost and savings percentage.
  • Parallel Resistor Calculator
    Enter resistor values in ohms (Ω), separated by commas, to instantly find the equivalent resistance of multiple resistors connected in parallel.
  • MPGe Calculator
    Calculate MPGe (miles per gallon equivalent) for electric vehicles from miles driven and kWh used, using the 33.7 kWh/gallon standard.
  • Miles Per kWh Calculator
    Calculate your electric vehicle's efficiency in miles per kWh. Enter miles driven and kWh used to get mi/kWh, kWh/100mi, and Wh/mile instantly.
  • LED Savings Calculator
    Calculate how much money you save each year by switching from incandescent or halogen bulbs to energy-efficient LED lighting.
  • Gas vs Electric Dryer Cost Calculator
    Compare the annual running cost of a gas vs electric clothes dryer (US). Enter loads, energy use and utility rates to see which is cheaper and your savings.
  • Electricity Cost – Single Usage Calculator
    Calculate the electricity cost of running a single appliance: enter its power in watts, hours used, and your price per kWh to get the exact cost.
  • Battery Capacity Calculator
    Convert battery capacity from mAh to watt-hours (Wh). Enter mAh and voltage to instantly find energy in Wh, kWh, and charge in Ah.
  • Battery Life Calculator
    Estimate how long a battery lasts from its capacity (mAh), the device load current (mA), and an efficiency factor. Instant runtime in hours and days.
  • Battery Life / Runtime Calculator
    Estimate how long a battery will last from its mAh capacity, the device's current draw in mA, and an efficiency factor. Get runtime in hours and minutes.
  • Amp Hours (Ah) Calculator
    Convert watt-hours to amp-hours instantly. Enter battery energy in Wh and voltage to find capacity in Ah and mAh using Ah = Wh / V.
  • 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.
  • Cost Per kWh Calculator
    Find your effective electricity rate per kWh by dividing your total monthly bill by the kilowatt-hours used. Fast, free energy cost calculator.
  • 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.
  • 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.
  • 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.
  • Heat Pump COP Calculator
    Calculate a heat pump's Coefficient of Performance (COP) from heat output and electrical input in kW. Free, instant efficiency 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).
  • 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.

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