How do you convert gigajoules to kilojoules?

To convert gigajoules (GJ) to kilojoules (kJ), multiply the energy in gigajoules by 1,000,000 (kilojoules = gigajoules × 1,000,000).

What is 5 gigajoules in kilojoules?

5 gigajoules (5 GJ) is equal to 5,000,000 kilojoules (5,000,000 kJ).

Which is larger, 1 gigajoule (GJ) or 1 kilojoule (kJ)?

One gigajoule (GJ) is larger than one kilojoule (kJ). Specifically, 1 GJ contains 1,000,000 kJ, whereas 1 kJ is 0.000001 GJ.

How do I convert back from kilojoules (kJ) to gigajoules (GJ)?

To reverse the calculation from kJ to GJ, multiply your kilojoule value by the inverse factor 0.000001 (or divide by 1,000,000). You can also click the Swap button in the tool above to flip directions in one click.

How many decimal places should I round GJ to kJ results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 5 GJ ≈ 5,000,000.00 kJ). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Gigajoules to Kilojoules Converter

Enter the energy in gigajoules below to convert it to kilojoules.

Kilojoules to Gigajoules (kJ → GJ)

Convert Gigajoules to Kilojoules

Enter a value in gigajoules (GJ) to convert to kilojoules (kJ).

Value (GJ)

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Result

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5,000,000kilojoules

5 GJ = 5,000,000 kJ

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Suggested Conversions

Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)

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Gigajoule to Kilojoule Conversion Table

Table showing various gigajoule measurements converted to kilojoules. Click any preset value or arrow to load it into the converter.

Gigajoules (GJ)	Kilojoules (kJ)
0.0000001 GJ	0.1 kJ
0.0000002 GJ	0.2 kJ
0.0000003 GJ	0.3 kJ
0.0000004 GJ	0.4 kJ
0.0000005 GJ	0.5 kJ
0.0000006 GJ	0.6 kJ
0.0000007 GJ	0.7 kJ
0.0000008 GJ	0.8 kJ
0.0000009 GJ	0.9 kJ
0.00000001 GJ	0.01 kJ

How to Convert Gigajoules to Kilojoules

To convert gigajoules to kilojoules, multiply the energy by the following conversion ratio: 1,000,000 kilojoules/gigajoule.

Since one gigajoule is equal to 1,000,000 kilojoules, you can use this simple formula to convert:

kilojoules = gigajoules × 1,000,000

The energy in kilojoules is equal to the energy in gigajoules multiplied by 1,000,000.

For example, here's how to convert 5 gigajoules to kilojoules using the formula above.

kilojoules = (5 GJ × 1,000,000) = 5,000,000 kJ

How Many Kilojoules Are in a Gigajoule?

There are 1,000,000 kilojoules in a gigajoule, which is why we use this value in the formula above.

1 GJ = 1,000,000 kJ|1 kJ = 0.000001 GJ

Our gigajoule to kilojoule calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

Gigajoules and kilojoules are both units used to measure energy. Keep reading to learn more about each unit.

What Is a Gigajoule?

A gigajoule is a unit of energy equal to 1,000,000,000 joules (J), the base unit for energy. Equal to 1,000,000,000 Joules, common in natural gas billing. [1]

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

In the metric system, "giga" is the standard SI prefix for billions, or 10⁹. This makes the gigajoule (GJ) a convenient decimal multiple of the joule (J).

In practice, gigajoules (GJ) 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 gigajoules in our Energy Converter.

What Is a Kilojoule?

A kilojoule is a unit of energy equal to 1,000 joules (J), the base unit for energy. Equal to 1,000 Joules. [2]

The kilojoule is classified as a metric and SI-compatible unit of energy. Kilojoules can be abbreviated as kJ; for example, 1 kilojoule can be written as 1 kJ.

In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilojoule (kJ) a convenient decimal multiple of the joule (J).

In practice, kilojoules (kJ) 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 kilojoules in our Energy Converter.

When converting energy between gigajoules (GJ) and kilojoules (kJ), keep full floating-point precision (1 GJ = 1,000,000 kJ; 1 kJ = 0.000001 GJ) during intermediate calculations and round only the final kilojoule figure to match your instrument tolerance.

More Gigajoule & Kilojoule Conversions

Need to calculate in the opposite direction? Use our kilojoules to gigajoules calculator to switch your starting unit immediately. You can also explore related tools such as converting kilojoules to gigajoules, converting joules to kilojoules, or converting kilocalories to kilojoules.

Convert from Gigajoules

Convert to Kilojoules

Frequently Asked Questions

There are 1,000,000 kilojoules (kJ) in 1 gigajoule (GJ). Conversely, 1 kilojoule (kJ) is equal to 0.000001 gigajoules (GJ).

Energy Converter

Quick Info

Direct Factor: 1 gigajoule (GJ) equals 1,000,000 kilojoules (kJ).
Inverse Factor: 1 kilojoule (kJ) equals 0.000001 gigajoules (GJ).
Formula: kilojoules = gigajoules × 1,000,000.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Gigajoule (GJ)

Equal to 1,000,000,000 Joules, common in natural gas billing.

Kilojoule (kJ)

Equal to 1,000 Joules.

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 — Gigajoules (GJ) to Kilojoules (kJ)
NIST CODATA Standard
[2]
NIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Gigajoule (GJ) & Kilojoule (kJ)
NIST SP 811 Specification
[3]
BIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (GJ to kJ)
BIPM Reference

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