How do you convert megajoules to megawatt-hours?

To convert megajoules (MJ) to megawatt-hours (MWh), multiply the energy in megajoules by 0.00027777 (megawatt-hours = megajoules × 0.00027777).

What is 5 megajoules in megawatt-hours?

5 megajoules (5 MJ) is equal to 0.00138888 megawatt-hours (0.00138888 MWh).

Which is larger, 1 megajoule (MJ) or 1 megawatt-hour (MWh)?

One megawatt-hour (MWh) is larger than one megajoule (MJ). Specifically, 1 MWh equals 3,600 MJ, while 1 MJ is 0.00027777 MWh.

How do I convert back from megawatt-hours (MWh) to megajoules (MJ)?

To reverse the calculation from MWh to MJ, multiply your megawatt-hour value by the inverse factor 3,600 (or divide by 0.00027777). You can also click the Swap button in the tool above to flip directions in one click.

How many decimal places should I round MJ to MWh results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 5 MJ ≈ 0.00 MWh). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Megajoules to Megawatt-hours Converter

Enter the energy in megajoules below to convert it to megawatt-hours.

Megawatt-hours to Megajoules (MWh → MJ)

Convert Megajoules to Megawatt-hours

Enter a value in megajoules (MJ) to convert to megawatt-hours (MWh).

Value (MJ)

From

Result

•

0.001388889megawatt-hours

5 MJ = 0.001388889 MWh

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Suggested Conversions

Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)

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Megajoule to Megawatt-hour Conversion Table

Table showing various megajoule measurements converted to megawatt-hours. Click any preset value or arrow to load it into the converter.

Megajoules (MJ)	Megawatt-hours (MWh)
1 MJ	0.000277778 MWh
2 MJ	0.000555556 MWh
2.5 MJ	0.000694444 MWh
5 MJ	0.0013889 MWh
10 MJ	0.0027778 MWh
15 MJ	0.0041667 MWh
20 MJ	0.0055556 MWh
25 MJ	0.0069444 MWh
30 MJ	0.0083333 MWh
50 MJ	0.0138889 MWh

How to Convert Megajoules to Megawatt-hours

To convert megajoules to megawatt-hours, multiply the energy by the following conversion ratio: 0.000277778 megawatt-hours/megajoule.

Since one megajoule is equal to 0.000277778 megawatt-hours, you can use this simple formula to convert:

megawatt-hours = megajoules × 0.000277778

The energy in megawatt-hours is equal to the energy in megajoules multiplied by 0.000277778.

For example, here's how to convert 5 megajoules to megawatt-hours using the formula above.

megawatt-hours = (5 MJ × 0.000277778) = 0.0013889 MWh

How Many Megawatt-hours Are in a Megajoule?

There are 0.000277778 megawatt-hours in a megajoule, which is why we use this value in the formula above.

1 MJ = 0.000277778 MWh|1 MWh = 3,600 MJ

Our megajoule to megawatt-hour calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

Megajoules and megawatt-hours are both units used to measure energy. Keep reading to learn more about each unit.

What Is a Megajoule?

A megajoule is a unit of energy equal to 1,000,000 joules (J), the base unit for energy. Equal to 1,000,000 Joules. [1]

The megajoule is classified as an International System of Units (SI) unit of energy. Megajoules can be abbreviated as MJ; for example, 1 megajoule can be written as 1 MJ.

In the metric system, "mega" is the standard SI prefix for millions, or 10⁶. This makes the megajoule (MJ) a convenient decimal multiple of the joule (J).

In practice, megajoules (MJ) are widely used across large-scale industrial, bulk, and macro-level energy specifications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.

Learn more about megajoules in our Energy Converter.

What Is a Megawatt-hour?

A megawatt-hour is a unit of energy equal to 3,600,000,000 joules (J), the base unit for energy. Equal to 1,000 kilowatt-hours (3.6 Gigajoules). [2]

The megawatt-hour is classified as a metric and SI-compatible unit of energy. Megawatt-hours can be abbreviated as MWh; for example, 1 megawatt-hour can be written as 1 MWh.

In the metric system, "mega" is the standard SI prefix for millions, or 10⁶. This makes the megawatt-hour (MWh) a convenient decimal multiple of the joule (J).

In practice, megawatt-hours (MWh) are widely used across large-scale industrial, bulk, and macro-level energy specifications within SI metric workflows, engineering documentation, and technical data sheets.

Learn more about megawatt-hours in our Energy Converter.

When converting energy between megajoules (MJ) and megawatt-hours (MWh), keep full floating-point precision (1 MJ = 0.000277778 MWh; 1 MWh = 3,600 MJ) during intermediate calculations and round only the final megawatt-hour figure to match your instrument tolerance.

More Megajoule & Megawatt-hour Conversions

Need to calculate in the opposite direction? Use our megawatt-hours to megajoules calculator to switch your starting unit immediately. You can also explore related tools such as converting megawatt-hours to megajoules, converting joules to calories, or converting calories to joules.

Convert from Megajoules

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Frequently Asked Questions

There are 0.00027777 megawatt-hours (MWh) in 1 megajoule (MJ). Conversely, 1 megawatt-hour (MWh) is equal to 3,600 megajoules (MJ).

Energy Converter

Quick Info

Direct Factor: 1 megajoule (MJ) equals 0.00027777 megawatt-hours (MWh).
Inverse Factor: 1 megawatt-hour (MWh) equals 3,600 megajoules (MJ).
Formula: megawatt-hours = megajoules ÷ 3600.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Megajoule (MJ)

Equal to 1,000,000 Joules.

Megawatt-hour (MWh)

Equal to 1,000 kilowatt-hours (3.6 Gigajoules).

Joule (J)

Coherent SI unit of energy and work (1 W·s = 1 N·m).

References

[1]NIST CODATA · CODATA Energy & Thermodynamic Constants
Source
[2]NIST SP 811 · NIST SP 811 App. B.9 (Energy, Work & Heat)
Source
[3]BIPM · Derived SI Unit: Joule (J)
Source

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References

NIST · BIPM · ISO

[1]
NIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Megajoules (MJ) to Megawatt-hours (MWh)
NIST CODATA Standard
[2]
NIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Megajoule (MJ) & Megawatt-hour (MWh)
NIST SP 811 Specification
[3]
BIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (MJ to MWh)
BIPM Reference

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