How do you convert kilocalories to joules?

To convert kilocalories (kcal) to joules (J), multiply the energy in kilocalories by 4,184 (joules = kilocalories × 4,184).

What is 5 kilocalories in joules?

5 kilocalories (5 kcal) is equal to 20,920 joules (20,920 J).

Which is larger, 1 kilocalorie (food calorie) (kcal) or 1 joule (J)?

One kilocalorie (food calorie) (kcal) is larger than one joule (J). Specifically, 1 kcal contains 4,184 J, whereas 1 J is 0.000239 kcal.

How do I convert back from joules (J) to kilocalories (kcal)?

To reverse the calculation from J to kcal, multiply your joule value by the inverse factor 0.000239 (or divide by 4,184). 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 J results to?

For everyday comparisons and quick estimates, rounding to 2 decimal places is usually sufficient (for example, 5 kcal ≈ 20,920.00 J). For engineering, laboratory, or machining specifications, select 4 or 6 decimals—or Scientific (10ⁿ) mode—in the calculator toolbar above.

Kilocalories to Joules Converter

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

Joules to Kilocalories (J → kcal)

Convert Kilocalories to Joules

Enter a value in kilocalories (kcal) to convert to joules (J).

Value (kcal)

From

Result

•

20,920joules

5 kcal = 20,920 J

Result updates automatically

Get Widget

Suggested Conversions

Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)

[1–3] ↓

Kilocalorie to Joule Conversion Table

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

Kilocalories (kcal)	Joules (J)
1 kcal	4,184 J
2 kcal	8,368 J
2.5 kcal	10,460 J
5 kcal	20,920 J
10 kcal	41,840 J
15 kcal	62,760 J
20 kcal	83,680 J
25 kcal	104,600 J
30 kcal	125,520 J
50 kcal	209,200 J

How to Convert Kilocalories to Joules

To convert kilocalories to joules, multiply the energy by the following conversion ratio: 4,184 joules/kilocalorie.

Since one kilocalorie is equal to 4,184 joules, you can use this simple formula to convert:

joules = kilocalories × 4,184

The energy in joules is equal to the energy in kilocalories multiplied by 4,184.

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

joules = (5 kcal × 4,184) = 20,920 J

How Many Joules Are in a Kilocalorie?

There are 4,184 joules in a kilocalorie, which is why we use this value in the formula above.

1 kcal = 4,184 J|1 J = 0.000239006 kcal

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

Kilocalories and joules 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 Joule?

Coherent SI unit of energy and work (1 W·s = 1 N·m). It serves as a primary reference unit for measuring energy across scientific and practical applications. [2]

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

As the primary coherent reference unit for energy in this category, all other energy units are mathematically anchored to the joule (J).

In practice, joules (J) are widely used across standard energy applications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.

Learn more about joules in our Energy Converter.

When converting energy between kilocalories (kcal) and joules (J), keep full floating-point precision (1 kcal = 4,184 J; 1 J = 0.000239006 kcal) during intermediate calculations and round only the final joule figure to match your instrument tolerance.

More Kilocalorie & Joule Conversions

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

Convert from Kilocalories

Convert to Joules

Frequently Asked Questions

There are 4,184 joules (J) in 1 kilocalorie (kcal). Conversely, 1 joule (J) is equal to 0.000239 kilocalories (kcal).

Energy Converter

Quick Info

Direct Factor: 1 kilocalorie (food calorie) (kcal) equals 4,184 joules (J).
Inverse Factor: 1 joule (J) equals 0.000239 kilocalories (kcal).
Formula: joules = kilocalories × 4,184.
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).

Joule (J)

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

Kilojoule (kJ)

Equal to 1,000 Joules.

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

Related Categories

Add This Calculator to Your Site

Free HTML widget · 4 embed formats

Embed the interactive Kilocalories to Joules converter on your blog, classroom, or documentation page.

Customize & Get Embed Code

References

NIST · BIPM · ISO

[1]
NIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Kilocalories (kcal) to Joules (J)
NIST CODATA Standard
[2]
NIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Kilocalorie (Food Calorie) (kcal) & Joule (J)
NIST SP 811 Specification
[3]
BIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (kcal to J)
BIPM Reference

Measurement Navigator78 Categories9 Scientific Domains

Browse All 78 Measurement Categories

A–Z Directory →Sitemap

Common ConvertersEveryday metric, imperial, and US customary converters for length, weight, volume, temperature, area, pressure, energy, speed, time, and data.