Energy and power calculator
Kinetic and potential energy, work, power, and what they cost in electricity.
How it works
Calculates kinetic energy, gravitational potential energy, work and power, and converts the result into kilowatt-hours and a running cost.
Kinetic energy scales with the square of speed, and that single fact explains most of road safety. Doubling speed quadruples the energy that has to be dissipated in a crash, and roughly quadruples the braking distance. A car at 60 km/h carries four times the energy it does at 30, not twice.
Potential energy is mgh, which makes the numbers involved in lifting things surprisingly small compared with heating them. Lifting a 70 kg person ten metres takes about 6,900 joules — less than two watt-hours, and about a thousandth of what boiling a kettle uses.
Power is energy per unit time. A joule per second is a watt, and a kilowatt-hour is 3.6 million joules.
This tool runs entirely in your browser. Nothing you enter is sent to a server, logged or stored, and the page keeps working with the network disconnected.
Common questions
- Why does speed matter so much in a crash?
- Kinetic energy is proportional to velocity squared. Doubling speed quadruples the energy that has to go somewhere.
- How many joules in a kilowatt-hour?
- 3,600,000. A kilowatt for an hour is 1,000 joules per second for 3,600 seconds.
Related pages
- Percentage calculator Work out a percentage of a number, what percent one number is of another, and percentage change.
- Loan and EMI calculator Monthly payment, total interest and total repaid for any loan amount, rate and term.
- BMI calculator Body mass index from height and weight, in metric or imperial, with what the number does and does not mean.
- Tip calculator Work out a tip and split the bill, with the per-person figure rounded sensibly.
- Age calculator Exact age in years, months and days from a date of birth, plus total days and the next birthday.
- Paint calculator How much paint a room needs, allowing for doors, windows and the number of coats.
- Compound interest calculator Growth of a lump sum plus regular contributions, with the interest shown separately.
- Calorie and BMR calculator Resting metabolic rate and daily calorie needs by activity level.
- Dog age calculator A dog's age in human years, using the research formula rather than multiplying by seven.
- Discount calculator Find the sale price and how much you save, including stacked discounts and tax.
Sources
- Calculated on this page — At One Place