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Millijoules to Attojoules Converter

Enter the energy in millijoules below to convert it to attojoules.

Convert Millijoules to Attojoules

Enter a value in millijoules (mJ) to convert to attojoules (aJ).

Result
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5e+15attojoules
5 mJ = 5e+15 aJ
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Reference:NIST CODATA (CODATA Energy & Thermodynamic Constants)
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Millijoule to Attojoule Conversion Table

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

Millijoules (mJ)Attojoules (aJ)
0.0000001 mJ100,000,000 aJ
0.0000002 mJ200,000,000 aJ
0.0000003 mJ300,000,000 aJ
0.0000004 mJ400,000,000 aJ
0.0000005 mJ500,000,000 aJ
0.0000006 mJ600,000,000 aJ
0.0000007 mJ700,000,000 aJ
0.0000008 mJ800,000,000 aJ
0.0000009 mJ900,000,000 aJ
0.00000001 mJ10,000,000 aJ

How to Convert Millijoules to Attojoules

To convert millijoules to attojoules, multiply the energy by the following conversion ratio: 1e+15 attojoules/millijoule.

Since one millijoule is equal to 1e+15 attojoules, you can use this simple formula to convert:

attojoules = millijoules × 1e+15

The energy in attojoules is equal to the energy in millijoules multiplied by 1e+15.

For example, here's how to convert 5 millijoules to attojoules using the formula above.

attojoules = (5 mJ × 1e+15) = 5e+15 aJ

How Many Attojoules Are in a Millijoule?

There are 1e+15 attojoules in a millijoule, which is why we use this value in the formula above.

1 mJ = 1e+15 aJ|1 aJ = 1e-15 mJ

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

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

What Is a Millijoule?

A millijoule is a unit of energy equal to 1/1,000 of a joule (0.001 J). One-thousandth of a Joule. [1]

The millijoule is classified as a metric and SI-compatible unit of energy. Millijoules can be abbreviated as mJ; for example, 1 millijoule can be written as 1 mJ.

In the metric system, "milli" is the standard SI prefix for thousandths, or 10⁻³. This makes the millijoule (mJ) a convenient decimal multiple of the joule (J).

In practice, millijoules (mJ) are widely used across fine-tolerance laboratory, analytical, and micro-scale energy measurements within SI metric workflows, engineering documentation, and technical data sheets.

What Is an Attojoule?

An attojoule is a unit of energy equal to 1/999,999,999,999,999,900 of a joule (1e-18 J). 10⁻¹⁸ Joules. [2]

The attojoule is classified as a metric and SI-compatible unit of energy. Attojoules can be abbreviated as aJ; for example, 1 attojoule can be written as 1 aJ.

When working with attojoules (aJ) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.

In practice, attojoules (aJ) are widely used across fine-tolerance laboratory, analytical, and micro-scale energy measurements within SI metric workflows, engineering documentation, and technical data sheets.

When converting energy between millijoules (mJ) and attojoules (aJ), keep full floating-point precision (1 mJ = 1e+15 aJ; 1 aJ = 1e-15 mJ) during intermediate calculations and round only the final attojoule figure to match your instrument tolerance.

More Millijoule & Attojoule Conversions

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

Frequently Asked Questions

There are 1.000000e+15 attojoules (aJ) in 1 millijoule (mJ). Conversely, 1 attojoule (aJ) is equal to 1.000000e-15 millijoules (mJ).

References

NIST · BIPM · ISO
  1. [1]
    NIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Millijoules (mJ) to Attojoules (aJ)
    NIST CODATA Standard
  2. [2]
    NIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Millijoule (mJ) & Attojoule (aJ)
    NIST SP 811 Specification
  3. [3]
    BIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (mJ to aJ)
    BIPM Reference
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