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Gigajoule to Megajoule Converter

Convert gigajoules to megajoules with our free online energy converter.

Quick Answer

1 Gigajoule = 1000 megajoules

Formula: Gigajoule × conversion factor = Megajoule

Use the calculator below for instant, accurate conversions.

Our Accuracy Guarantee

All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.

Last verified: February 2026Reviewed by: Sam Mathew, Software Engineer

Gigajoule to Megajoule Calculator

How to Use the Gigajoule to Megajoule Calculator:

  1. Enter the value you want to convert in the 'From' field (Gigajoule).
  2. The converted value in Megajoule will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Energy category.
  4. Click the swap button (⇌) to reverse the conversion direction.
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How to Convert Gigajoule to Megajoule: Step-by-Step Guide

Converting Gigajoule to Megajoule involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

MJ = GJ × 1000

Example Calculation:

1 GJ = 1000 MJ

Disclaimer: For Reference Only

These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.

Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.

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📋 Unit Symbols

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What is a Gigajoule and a Megajoule?

1 GJ = 1,000,000,000 joules (J)

1 MJ = 1,000,000 J = 1,000 kJ = 0.278 kWh = 948 BTU = 239 kcal

Note: The Gigajoule is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Megajoule belongs to the imperial/US customary system.

Common Uses and Applications: gigajoules vs megajoules

Explore the typical applications for both Gigajoule (imperial/US) and Megajoule (imperial/US) to understand their common contexts.

Common Uses for gigajoules

Used in physics, engineering, energy systems, and scientific calculations where this energy scale is appropriate for the application.

When to Use megajoules

Automotive: Crash test energy, fuel energy content specifications. Energy: Natural gas content, biomass energy, fuel comparisons. Manufacturing: Industrial heating, process energy requirements. Nutrition: Large-scale food production energy calculations.

Additional Unit Information

About Gigajoule (GJ)

How do I convert GJ to joules?

Formula: J = GJ × 1,000,000,000

Gigajoule to Joules converter →

How do I convert GJ to kWh?

To convert to kilowatt-hours, first convert to joules, then divide by 3,600,000.

Gigajoule to kWh converter →

What is Gigajoule used for?

Gigajoule is used in contexts where the energy scale makes it convenient compared to very large or very small joule values. It provides a practical measurement unit for specific applications.

About Megajoule (MJ)

How do I convert MJ to kWh?

Formula: kWh = MJ × 0.278 (or MJ ÷ 3.6)

Examples:

  • 1 MJ = 0.278 kWh
  • 10 MJ = 2.78 kWh
  • 100 MJ = 27.8 kWh
  • 3.6 MJ = 1 kWh

MJ to kWh converter →

How many MJ in a liter of gasoline?

1 liter of gasoline ≈ 32 MJ (varies slightly by formulation)

Other fuels:

  • Diesel: ~36 MJ/liter (higher energy density)
  • E85 ethanol: ~24 MJ/liter
  • LPG: ~26 MJ/liter
  • Jet fuel: ~35 MJ/liter

How do I convert MJ to joules?

Formula: J = MJ × 1,000,000

Examples:

  • 1 MJ = 1,000,000 J
  • 0.1 MJ = 100,000 J = 100 kJ
  • 10 MJ = 10,000,000 J = 10,000 kJ

MJ to Joules converter →

How many MJ does a car use per 100 km?

Typical fuel consumption:

  • Small car (5 L/100km): ~160 MJ/100km
  • Medium car (8 L/100km): ~256 MJ/100km
  • SUV (12 L/100km): ~384 MJ/100km
  • Electric car (20 kWh/100km): ~72 MJ/100km

Gasoline cars use roughly 2-3x more energy than EVs due to engine efficiency losses.

Conversion Table: Gigajoule to Megajoule

Gigajoule (GJ)Megajoule (MJ)
0.5500
11,000
1.51,500
22,000
55,000
1010,000
2525,000
5050,000
100100,000
250250,000
500500,000
1,0001,000,000

People Also Ask

How do I convert Gigajoule to Megajoule?

To convert Gigajoule to Megajoule, enter the value in Gigajoule in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our energy converter page to convert between other units in this category.

Learn more →

What is the conversion factor from Gigajoule to Megajoule?

The conversion factor depends on the specific relationship between Gigajoule and Megajoule. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.

Can I convert Megajoule back to Gigajoule?

Yes! You can easily convert Megajoule back to Gigajoule by using the swap button (⇌) in the calculator above, or by visiting our Megajoule to Gigajoule converter page. You can also explore other energy conversions on our category page.

Learn more →

What are common uses for Gigajoule and Megajoule?

Gigajoule and Megajoule are both standard units used in energy measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our energy converter for more conversion options.

For more energy conversion questions, visit our FAQ page or explore our conversion guides.

Helpful Conversion Guides

Learn more about unit conversion with our comprehensive guides:

📚 How to Convert Units

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🔢 Conversion Formulas

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⚖️ Metric vs Imperial

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⚠️ Common Mistakes

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All Energy Conversions

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Other Energy Units and Conversions

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Verified Against Authority Standards

All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.

NIST Reference on Constants, Units and Uncertainty

National Institute of Standards and Technology — Fundamental physical constants and unit conversions

BIPM SI Units

Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards

ISO 80000

International Organization for Standardization — Quantities and units international standards series

Last verified: February 19, 2026