Wh to kWh Calculator
Watt-hours and kilowatt-hours are both units of energy. Enter any Wh value to convert it directly to kWh and estimate its electricity cost; no time period is needed.
Quick answerDivide watt-hours by 1,000 to get kilowatt-hours. Exactly 1 Wh = 0.001 kWh, 100 Wh = 0.1 kWh, 1,000 Wh = 1 kWh, and 2,500 Wh = 2.5 kWh. At $0.17/kWh, 2,500 Wh costs about $0.43.
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How it works
Kilowatt-hours = watt-hours ÷ 1,000. Cost = kilowatt-hours × electricity rate. The conversion is exact because kilo means 1,000: 2,500 Wh ÷ 1,000 = 2.5 kWh, and 2.5 kWh × $0.17/kWh = $0.425, displayed as $0.43.
Wh to kWh conversion table
Divide any watt-hour value by 1,000 to get kilowatt-hours. These energy conversions are exact.
| Watt-hours | Kilowatt-hours |
|---|---|
| 1 Wh | 0.001 kWh |
| 10 Wh | 0.01 kWh |
| 50 Wh | 0.05 kWh |
| 100 Wh | 0.1 kWh |
| 250 Wh | 0.25 kWh |
| 500 Wh | 0.5 kWh |
| 1,000 Wh | 1 kWh |
| 2,000 Wh | 2 kWh |
| 2,500 Wh | 2.5 kWh |
| 5,000 Wh | 5 kWh |
| 10,000 Wh | 10 kWh |
To convert in the opposite direction, multiply kWh by 1,000 or use the linked kWh to Wh calculator.
Worked example: convert 2,500 Wh to kWh and cost
Divide 2,500 Wh by 1,000. The result is 2.5 kWh. Both values describe the same amount of energy; only the scale and unit label change.
At an electricity rate of $0.17/kWh, cost = 2.5 kWh × $0.17/kWh = $0.425, which rounds to $0.43. The cost field does not add fixed service charges, taxes, demand charges, or battery losses.
Wh to kWh is energy to energy—not watts to kWh
Watt-hours and kilowatt-hours measure energy, so their conversion always uses the fixed 1,000-to-1 factor. Watts measure power. To turn watts into kWh, you must also know time: kWh = watts × hours ÷ 1,000.
For example, a 500 W appliance does not have one fixed kWh value. It uses 0.5 kWh in one hour, 1 kWh in two hours, or 4 kWh in eight hours. Use the watts-to-kWh calculator when your starting value is W rather than Wh.
Where Wh and kWh are normally used
Portable batteries, power banks, small solar generators, and device measurements are often labelled in Wh because their energy is below 1 kWh. Electricity bills, electric vehicles, home batteries, and household consumption normally use kWh so the numbers stay compact.
Convert both values to the same unit before comparing capacity or energy use. Rated battery capacity is not always the energy delivered at an outlet: inverter, voltage-conversion, standby, temperature, and discharge losses can reduce usable output.
Why the division by 1,000 is exact
The International Bureau of Weights and Measures defines the SI prefix kilo as 10³, or 1,000. NIST lists 1 Wh as 3.6 × 10³ joules and 1 kWh as 3.6 × 10⁶ joules. Dividing those energy factors gives the same exact ratio: 1 kWh = 1,000 Wh, so 1 Wh = 0.001 kWh.
The unit conversion itself requires no efficiency assumption. Efficiency matters only when comparing rated stored energy with energy actually delivered or when estimating the input required to charge a battery.
Sources used for assumptions: BIPM — SI Brochure, 9th edition: kilo is 10³; NIST — Guide to the SI, Appendix B.9: Wh and kWh energy factors.
Frequently asked questions
How do I convert Wh to kWh?
Divide watt-hours by 1,000. For example, 2,500 Wh ÷ 1,000 = 2.5 kWh.
How many Wh are in 1 kWh?
Exactly 1,000 Wh. In the reverse direction, 1 Wh equals 0.001 kWh.
How many kWh is 100 Wh?
100 Wh equals 0.1 kWh because 100 ÷ 1,000 = 0.1.
How many kWh is 500 Wh?
500 Wh equals 0.5 kWh. At $0.17/kWh, that energy costs about $0.09 before fixed charges or taxes.
Is Wh to kWh the same as watts to kWh?
No. Wh and kWh are energy units and use a fixed division by 1,000. Watts measure power, so a watts-to-kWh conversion also requires operating time in hours.
Why do batteries use Wh instead of kWh?
Wh keeps capacities below 1 kWh easy to read. A 500 Wh battery could also be labelled 0.5 kWh; the amount of rated energy is the same.
Is Wh the same as mAh?
No. Wh measures energy and mAh measures electric charge. Converting mAh to Wh also requires voltage.
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