Conversion guide

Watts to Watt-hours conversion

Calculate energy in Wh from average power in W and an explicit duration in hours. Runs locally in your browser.

Watt-hours to watts Watts to kilowatt-hours

Instant result

Result

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Enter values to convert.

Inputs —

Mode —

Formula —

Formulas

Core equations used by this converter.

EnergyE(Wh) = P(W) × Δt(h)

Exact definition1 W = 1 J/s

iAverage power is measured over the same interval as the energy. Displayed results may be rounded.

How to use

Enter average power

Use W for the first field.

Enter the duration

Use hours. The duration must be nonnegative.

Read the result

The result updates in Wh.

Example conversions

Common values with formula and result.

50 W for 2 hours

50 × 2 = 100 Wh

100 Wh

100 W for 5 hours

100 × 5 = 500 Wh

500 Wh

10 W for 24 hours

10 × 24 = 240 Wh

240 Wh

200 W for 0.5 hours

200 × 0.5 = 100 Wh

100 Wh

Watts to Watt-hours conversion specification

Version 1.1.1 · Engine tested

Calculation status

Engine tested 4 published cases
Named expert review Not performed
Calculation version 1.1.1

Review policy

Definition: Multiply average power by the elapsed time to find energy. Use hours for the duration on this page.
What it calculates: Calculate energy in Wh from average power in W and an explicit duration in hours. Runs locally in your browser.
Inputs: Average power (W)
Duration (h)
Outputs: Energy (Wh)
Formula: E(Wh) = P(W) × Δt(h)
Watts to watt-hours table: Power (W) 1 hour 5 hours 10 hours
5 W 5 Wh 25 Wh 50 Wh
10 W 10 Wh 50 Wh 100 Wh
50 W 50 Wh 250 Wh 500 Wh
100 W 100 Wh 500 Wh 1000 Wh
500 W 500 Wh 2500 Wh 5000 Wh
1000 W 1000 Wh 5000 Wh 10 000 Wh
Assumptions: Average power is measured over the same interval as the energy.
Runs locally with pinned UUCE unit definitions.
Units: W
h
Wh
Boundary conditions: Empty or invalid input yields no valid result.
Average power must be nonnegative.
Duration must be nonnegative.
Example: 50 W for 2 hours → 100 Wh
Validation cases: 50 W for 2 hours → 100 Wh
100 W for 5 hours → 500 Wh
10 W for 24 hours → 240 Wh
200 W for 0.5 hours → 100 Wh
Sources: NIST SP 330, Appendix 1 (https://www.nist.gov/pml/special-publication-330/sp-330-appendix-1)
NIST SP 330, Section 4 (https://www.nist.gov/pml/special-publication-330/sp-330-section-4)
CalculatorX UUCE snapshot 0.3.0-preview.3
Calculation version: 1.1.1

Power (W)	1 hour	5 hours	10 hours
5 W	5 Wh	25 Wh	50 Wh
10 W	10 Wh	50 Wh	100 Wh
50 W	50 Wh	250 Wh	500 Wh
100 W	100 Wh	500 Wh	1000 Wh
500 W	500 Wh	2500 Wh	5000 Wh
1000 W	1000 Wh	5000 Wh	10 000 Wh

Background

Interpretation and common distinctions.

Enter the duration in hours to calculate energy. Results for Watts to Watt-hours conversion update locally in your browser.

Frequently asked questions

Key distinctions behind the conversion.

How do you convert using Watts to Watt-hours conversion?

Multiply average power by the elapsed time to find energy. Example: 50 W for 2 hours → 100 Wh.

Can I switch direction?

Open a related calculator to use a different input and output pair.

Does this run online or locally?

Calculation runs locally in your browser. Values are not uploaded.

How precise are the results?

Results follow the formulas on this page. Round to the precision your use case needs.