Utilities

  • Volts, Amps, Watts, Ohms Calculator
    Ohm's law calculator: enter any two of voltage, current, resistance or power and instantly compute the other two using V=IR, P=VI, P=I²R, P=V²/R.
  • Pool Water Volume Calculator
    Calculate swimming pool water volume in gallons and liters from length, width, and average depth in feet or meters. Fast, accurate, and free.
  • Flight CO₂ Emissions Calculator
    Estimate the CO₂ emissions of any flight from distance, flight type and passenger count. See kg, tonnes and trees needed to offset your air travel.
  • Monthly Electricity Bill Estimator
    Estimate your monthly electricity bill from kWh usage, your rate per kWh, and any fixed service charge. See monthly and annual cost instantly.
  • Car CO2 Emissions Calculator
    Estimate the CO2 emissions and carbon footprint of your car trips from distance, fuel economy and fuel type (gasoline or diesel).
  • Dew Point Calculator
    Calculate dew point from air temperature and relative humidity using the Magnus-Tetens formula. Instant results in °C with dew point spread.
  • Appliance Electricity Cost Calculator
    Calculate how much an appliance costs to run. Enter watts, hours used, days and your kWh rate to get daily, monthly and yearly electricity cost.
  • LED vs Incandescent Bulb Savings Calculator
    Calculate how much money and electricity you save each year by switching from incandescent bulbs to LEDs based on wattage, usage hours and energy price.
  • Natural Gas Cost Calculator
    Estimate your natural gas bill from therms used, price per therm, and any fixed monthly charge. Fast, free natural gas cost calculator.
  • Water Tank Volume Calculator
    Calculate water tank capacity in liters, US & UK gallons, and cubic meters. Works for cylindrical and rectangular tanks using simple dimensions.
  • Propane Tank Usage Calculator
    Find out how long your propane tank will last. Enter gallons of propane and your appliance's BTU/hour to get run time in hours and days.
  • Torque Conversion Calculator
    Convert torque between Newton-meters, pound-feet, pound-inches and kilogram-force meters instantly. Free, accurate torque unit converter with formula.
  • Data Transfer Rate Converter
    Convert data transfer rates between bps, Kbps, Mbps, Gbps, and B/s, KB/s, MB/s, GB/s instantly. Free online bandwidth and speed unit converter.
  • Length Conversion Calculator
    Convert length between mm, cm, m, km, inches, feet, yards and miles. Fast, accurate metric-to-imperial length unit converter with formula.
  • Heating & Cooling Load Calculator (Quick Manual J)
    Estimate your home's heating and cooling load in BTU/hr with this quick Manual J-style calculator. Based on US ACCA rule-of-thumb factors.
  • Rainwater Harvesting Calculator
    Calculate how many gallons of rainwater you can harvest from your roof based on catchment area, rainfall depth, and runoff coefficient.
  • Air Conditioner BTU Calculator
    Find the right air conditioner BTU for any room. Enter length, width, occupants, and sun exposure to size your AC unit instantly.
  • Metric (SI Prefix) Units Conversion Calculator
    Convert a value between SI metric prefixes (giga, mega, kilo, milli, micro, nano and more) for any base unit. Instant powers-of-ten conversion factor.
  • Kilowatts to Amps Calculator
    Convert kilowatts (kW) to amps for DC, single-phase and three-phase AC circuits. Enter power, voltage and power factor to get current in amperes.
  • Amps to Watts Calculator
    Convert amps to watts for DC, AC single-phase and three-phase circuits. Enter current, voltage and power factor to get watts and kilowatts instantly.
  • Water Heating Energy Calculator
    Calculate the energy needed to heat water using Q = m·c·ΔT. Enter volume, start/end temperature and efficiency to get kWh, kJ and joules.
  • Fuel Economy Unit Converter (km/L ⇔ mpg ⇔ L/100km)
    Convert fuel economy between km/L, L/100km, L/km, US mpg and Imperial mpg, plus gal/100mi. Enter one value and get all eight units at once.
  • Watts to Amps Calculator
    Convert watts to amps for DC and single-phase AC circuits. Enter power, voltage and power factor to get current in amps instantly.
  • 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.

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