Conversion guide

Watts to Kilojoules conversion

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

Kilojoules to watts Watts to joules

Instant result

Result

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Enter values to convert.

Inputs —

Mode —

Formula —

Formulas

Core equations used by this converter.

EnergyE(kJ) = P(W) × Δt(s) ÷ 1000

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 seconds. The duration must be nonnegative.

Read the result

The result updates in kJ.

Example conversions

Common values with formula and result.

1000 W for 3 s

1000 × 3 ÷ 1000 = 3 kJ

3 kJ

500 W for 10 s

500 × 10 ÷ 1000 = 5 kJ

5 kJ

100 W for 60 s

100 × 60 ÷ 1000 = 6 kJ

6 kJ

2000 W for 1 hour (3600 s)

2000 × 3600 ÷ 1000 = 7200 kJ

7200 kJ

Watts to Kilojoules 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 seconds for the duration on this page.
What it calculates: Calculate energy in kJ from average power in W and an explicit duration in seconds. Runs locally in your browser.
Inputs: Average power (W)
Duration (s)
Outputs: Energy (kJ)
Formula: E(kJ) = P(W) × Δt(s) ÷ 1000
Watts to kilojoules table: Power (W) Energy in 1 s (kJ) Energy in 1 min (kJ) Energy in 1 h (kJ)
100 W 0.1 6 360
500 W 0.5 30 1800
1000 W 1.0 60 3600
2000 W 2.0 120 7200
5000 W 5.0 300 18 000
Assumptions: Average power is measured over the same interval as the energy.
Runs locally with pinned UUCE unit definitions.
Units: W
s
kJ
Boundary conditions: Empty or invalid input yields no valid result.
Average power must be nonnegative.
Duration must be nonnegative.
Example: 1000 W for 3 s → 3 kJ
Validation cases: 1000 W for 3 s → 3 kJ
500 W for 10 s → 5 kJ
100 W for 60 s → 6 kJ
2000 W for 1 hour (3600 s) → 7200 kJ
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)	Energy in 1 s (kJ)	Energy in 1 min (kJ)	Energy in 1 h (kJ)
100 W	0.1	6	360
500 W	0.5	30	1800
1000 W	1.0	60	3600
2000 W	2.0	120	7200
5000 W	5.0	300	18 000

Background

Interpretation and common distinctions.

Enter the duration in seconds to calculate energy. Results for Watts to Kilojoules conversion update locally in your browser.

Frequently asked questions

Key distinctions behind the conversion.

How do you convert using Watts to Kilojoules conversion?

Multiply average power by the elapsed time to find energy. Example: 1000 W for 3 s → 3 kJ.

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.