How do you convert kilocalories to gigajoules?

To convert kilocalories (kcal) to gigajoules (GJ), multiply the energy in kilocalories by 0.00000418 (gigajoules = kilocalories × 0.00000418).

What is 5 kilocalories in gigajoules?

5 kilocalories (5 kcal) is equal to 0.00002092 gigajoules (0.00002092 GJ).

Which is larger, 1 kilocalorie (food calorie) (kcal) or 1 gigajoule (GJ)?

One gigajoule (GJ) is larger than one kilocalorie (food calorie) (kcal). Specifically, 1 GJ equals 239,005.73613766 kcal, while 1 kcal is 0.00000418 GJ.

How do I convert back from gigajoules (GJ) to kilocalories (kcal)?

To reverse the calculation from GJ to kcal, multiply your gigajoule value by the inverse factor 239,005.73613766 (or divide by 0.00000418). You can also click the Swap button in the tool above to flip directions in one click.

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

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

Kilocalories to Gigajoules Converter

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

Gigajoules to Kilocalories (GJ → kcal)

Convert Kilocalories to Gigajoules

Enter a value in kilocalories (kcal) to convert to gigajoules (GJ).

Value (kcal)

From

Result

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0.00002092gigajoules

5 kcal = 0.00002092 GJ

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Suggested Conversions

Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)

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Kilocalorie to Gigajoule Conversion Table

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

Kilocalories (kcal)	Gigajoules (GJ)
1 kcal	0.000004184 GJ
10 kcal	0.00004184 GJ
100 kcal	0.0004184 GJ
1,000 kcal	0.004184 GJ
10,000 kcal	0.04184 GJ
100,000 kcal	0.4184 GJ
1,000,000 kcal	4.184 GJ
5,000,000 kcal	20.92 GJ
10,000,000 kcal	41.84 GJ
25,400,000 kcal	106.2736 GJ

How to Convert Kilocalories to Gigajoules

To convert kilocalories to gigajoules, multiply the energy by the following conversion ratio: 0.000004184 gigajoules/kilocalorie.

Since one kilocalorie is equal to 0.000004184 gigajoules, you can use this simple formula to convert:

gigajoules = kilocalories × 0.000004184

The energy in gigajoules is equal to the energy in kilocalories multiplied by 0.000004184.

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

gigajoules = (5 kcal × 0.000004184) = 0.00002092 GJ

How Many Gigajoules Are in a Kilocalorie?

There are 0.000004184 gigajoules in a kilocalorie, which is why we use this value in the formula above.

1 kcal = 0.000004184 GJ|1 GJ = 239,005.7361377 kcal

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

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

What Is a Kilocalorie?

A kilocalorie is a unit of energy equal to 4,184 joules (J), the base unit for energy. Dietary Calorie equal to 1,000 small calories (4,184 Joules). [1]

The kilocalorie is classified as a standard unit of energy. Kilocalories can be abbreviated as kcal; for example, 1 kilocalorie can be written as 1 kcal.

In the metric system, "kilo" is the standard SI prefix for thousands, or 10³. This makes the kilocalorie (kcal) a convenient decimal multiple of the calorie (cal).

In practice, kilocalories (kcal) are widely used across large-scale industrial, bulk, and macro-level energy specifications within international standard workflows, engineering documentation, and technical data sheets.

Learn more about kilocalories in our Energy Converter.

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. [2]

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.

When converting energy between kilocalories (kcal) and gigajoules (GJ), keep full floating-point precision (1 kcal = 0.000004184 GJ; 1 GJ = 239,005.7361377 kcal) during intermediate calculations and round only the final gigajoule figure to match your instrument tolerance.

More Kilocalorie & Gigajoule Conversions

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

Convert from Kilocalories

Convert to Gigajoules

Frequently Asked Questions

There are 0.00000418 gigajoules (GJ) in 1 kilocalorie (kcal). Conversely, 1 gigajoule (GJ) is equal to 239,005.73613766 kilocalories (kcal).

Energy Converter

Quick Info

Direct Factor: 1 kilocalorie (food calorie) (kcal) equals 0.00000418 gigajoules (GJ).
Inverse Factor: 1 gigajoule (GJ) equals 239,005.73613766 kilocalories (kcal).
Formula: gigajoules = kilocalories × 0.00000418.
Verified Precision: Anchored to official NIST SP 811 and ISO/IEC 80000 standards.

Units Comparison

Kilocalorie (Food Calorie) (kcal)

Dietary Calorie equal to 1,000 small calories (4,184 Joules).

Gigajoule (GJ)

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

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

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