Electricity Calculator

  • Battery Discharge Time Calculator
    Estimate how long a battery will last from its amp-hour capacity, load current, and usable depth of discharge. Free runtime calculator: t = (Ah × DoD) / A.
  • kWh from Amps, Volts and Hours Calculator
    Calculate electricity usage in kWh from amps, volts and hours. Enter current, voltage and run time to get energy used, power in watts and cost.
  • Electricity Bill Calculator
    Estimate your electricity bill from units consumed (kWh), the per-unit rate, and any fixed charge. Free, fast, and works with any currency.
  • Power from Torque and RPM Calculator
    Calculate mechanical power in kW, watts and horsepower from torque (N·m) and rotational speed (RPM) using P = T × RPM / 9549.
  • EV vs Gas Cost per Mile Calculator
    Compare the cost per mile of driving an electric vehicle versus a gas car. Enter kWh/mile, electricity price, gas price, and MPG to see your savings.
  • EV kWh per 100 km Calculator
    Calculate your electric vehicle energy consumption in kWh per 100 km from the energy used and distance driven. Get km/kWh and Wh/km too.
  • Milliamps to Amps Calculator
    Convert milliamps (mA) to amps (A) instantly. Enter a current in mA and get the value in amperes using A = mA / 1000.
  • kWh to BTU Calculator
    Convert kilowatt-hours (kWh) to British Thermal Units (BTU) instantly. Enter kWh and get BTU using the factor 1 kWh = 3412.142 BTU.
  • Amps to Milliamps Calculator
    Convert amps (A) to milliamps (mA) instantly. Enter a current value in amperes and get the equivalent in milliamps using mA = A × 1000.
  • Battery Amp-Hours Needed Calculator
    Calculate the battery amp-hours (Ah) needed from watts, runtime hours and voltage. Includes depth-of-discharge adjustment for any 12V, 24V or 48V battery.
  • Battery State of Charge Calculator
    Estimate battery State of Charge (SOC %) from a measured voltage reading using linear interpolation between empty (Vmin) and full (Vmax) voltages.
  • Kilowatts to Watts Calculator
    Convert kilowatts (kW) to watts (W) instantly. Enter a power value in kW and get the exact result in watts using W = kW × 1000.
  • Watts to Kilowatts Calculator
    Convert watts (W) to kilowatts (kW) instantly. Just divide power in watts by 1000 to get kilowatts. Fast, accurate, free W to kW converter.
  • Solar Panel Battery Charge Time Calculator
    Estimate how many hours of sunlight a solar panel needs to charge a battery from your battery Wh, panel watts, and system efficiency.
  • Lumens Needed Calculator
    Calculate how many lumens you need to light a room. Multiply floor area (m²) by the recommended lux level to get total lumens for any space.
  • Thevenin Equivalent Calculator
    Compute the Thevenin equivalent of a circuit. Enter open-circuit voltage and short-circuit current to find Thevenin voltage Vth and resistance Rth.
  • Peak-to-Peak Voltage Calculator
    Convert between peak-to-peak (Vpp), peak (Vpeak) and RMS (Vrms) voltage for a sine wave. Enter any one value to get the others instantly.
  • Resistance Temperature Coefficient Calculator
    Calculate how a conductor resistance changes with temperature using R = R₀(1 + α·ΔT). Enter reference resistance, temperature coefficient and temperatures.
  • Battery C-Rate Calculator
    Calculate charge/discharge current from battery capacity and C-rate using I = C-rate × Capacity. Get amps plus the theoretical full charge/discharge time.
  • Synchronous Speed Calculator
    Calculate the synchronous speed of an AC motor or generator from supply frequency and number of poles using Ns = 120f/P. Get results in RPM and rev/s.
  • Volts to Watts Calculator
    Convert volts to watts instantly. Enter voltage (V) and current (A) to calculate electrical power in watts using P = V × I.
  • mAh to Wh Battery Capacity Calculator
    Convert battery capacity from mAh to Wh instantly. Enter milliamp-hours and voltage to get watt-hours and kilowatt-hours for any battery.
  • IoT Sensor Battery Life Calculator
    Estimate how long an IoT sensor or wireless device will run from its battery using capacity (mAh), average current draw (mA), and a usable-capacity derating factor.
  • Solar Panel Payback & ROI Calculator
    Calculate your solar panel payback period and ROI. Enter system cost, annual savings, and lifespan to see break-even years, lifetime savings, and return.

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