Tool library
Energy & Power Conversion Tools
One connected toolkit for every watt, joule, kilowatt-hour, amp, and calorie conversion — free, instant, and private in your browser.
Choose a converter
Each tool runs entirely in your browser and cross-links to the rest of the cluster.
- Watts to JoulesThe full power × time energy calculator with three modes.Energy
- kWh to JoulesTurn the kWh figure on your electricity bill into joules — 1 kWh = 3,600,000 J.Energy
- Joules to kWhConvert a joule or megajoule figure into billable kilowatt-hours — divide by 3,600,000.Energy
- Watts to AmpsCalculate amps from watts and volts for DC and AC circuits — I = P ÷ V.Power
- Joules to CaloriesConvert joules into calories and food Calories (kcal) — 1 cal = 4.184 J.Energy
- Amps to WattsCalculate watts from amps and volts for DC and AC circuits — P = I × V.Power
- Volts to WattsConvert potential (volts) to power (watts) given the electric current — P = V × I.Power
- Wh to JoulesConvert watt-hours to joules — 1 Wh = 3,600 J.Energy
- BTU to JoulesConvert heating or cooling thermal units (BTU) to joules — 1 BTU = 1,055.06 J.Energy
- BTU/hr to WattsConvert heating/cooling power (BTU/hr) to electrical watts — 1 BTU/hr = 0.293071 W.Power
- mAh to JoulesConvert battery milliamp-hours (mAh) to joules given nominal voltage — E = mAh × V × 3.6.Energy
- Battery Run TimeEstimate battery run time under a given load — active hours = capacity × volts × DoD ÷ load.Energy
- Appliance Energy CostCalculate electricity cost for any appliance — cost = power × hours ÷ 1,000 × rate.Energy
- Ohm's LawSolve Voltage, Current, Resistance, and Power from any two inputs using Ohm's Law.Power
- Voltage DropCalculate voltage drop over long electrical wire runs — V_drop = 2 × K × I × L ÷ Area.Power
- AC BTUCalculate heating/cooling BTUs needed for a room — base BTU = area × 20.Power
- Watts to HPTurn watts into horsepower — 1 mechanical hp = 745.7 W.Power
- HP to WattsTurn horsepower into watts — 1 mechanical hp = 745.7 W.Power
- Joules to WattsTurn joules of energy into watts of power — W = J ÷ seconds.Power
- Watts to OhmsFind resistance in ohms from power and voltage — R = V² ÷ P.Power
- Joules to eVTurn joules into electronvolts — 1 eV = 1.602176634×10⁻¹⁹ J.Energy
- Electricity CostFind the running cost of any device — cost = (W ÷ 1000) × hours × rate.Energy
- Watts to AhSize a battery from a load — Ah = (watts × hours) ÷ volts.Energy
- Ah to WattsFind the load a battery supports — W = (Ah × volts) ÷ hours.Power
- Watts to VoltsFind voltage from power and current — V = P ÷ I.Power
- Joules to WhTurn joules into watt-hours — 1 Wh = 3,600 J.Energy
- Joules to BTUTurn joules into BTU — 1 BTU = 1,055.06 J.Energy
- Watts to Joules per SecondWatts and joules per second are the same unit — 1 W = 1 J/s.Power
Quick facts
- 1 Watt is exactly equal to 1 Joule per second.
- A typical 60W lightbulb left on for 1 hour uses 216,000 Joules of energy.
- Kilowatt-hours (kWh) are just big Joules! 1 kWh equals 3,600,000 Joules.
- Your electricity bill is priced in kWh because Joules are simply too small for practical daily use.