Enter a mass (amu, g, kg, or lb) or an energy value, and the calculator will compute the other using mass–energy equivalence (E = mc²) with the speed of light in vacuum (c = 299,792,458 m/s).
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Amu To Joules Formula
The following formula is used to calculate the rest-energy equivalent in Joules from a mass given in atomic mass units (amu). Since E = mc2 requires mass in kilograms, the amu value must be converted to kg first.
E = m_{\text{amu}} \times (1.66053906660\times 10^{-27}) \times c^2Variables:
- E is the energy in Joules (J)
- mamu is the mass in atomic mass units (amu)
- 1 amu = 1.66053906660×10-27 kg
- c is the speed of light in vacuum in meters per second (m/s), which is 299,792,458 m/s (≈ 3.00 × 108 m/s)
To calculate the energy in Joules, first convert the mass from amu to kilograms using 1 amu = 1.66053906660×10-27 kg, then multiply that mass (in kg) by the square of the speed of light in vacuum. The result is the energy in Joules.
| Mass (amu) | Energy (J) | Energy (eV) |
|---|---|---|
| 0.5 | 7.46e-11 | 4.66e8 |
| 1 | 1.49e-10 | 9.31e8 |
| 2 | 2.98e-10 | 1.86e9 |
| 4 | 5.97e-10 | 3.73e9 |
| 12 | 1.79e-9 | 1.12e10 |
| 14 | 2.09e-9 | 1.30e10 |
| 16 | 2.39e-9 | 1.49e10 |
| 18 | 2.69e-9 | 1.68e10 |
| 20 | 2.98e-9 | 1.86e10 |
| 24 | 3.58e-9 | 2.24e10 |
| 28 | 4.18e-9 | 2.61e10 |
| 32 | 4.78e-9 | 2.98e10 |
| 35.5 | 5.30e-9 | 3.31e10 |
| 40 | 5.97e-9 | 3.73e10 |
| 56 | 8.36e-9 | 5.22e10 |
| 63.5 | 9.48e-9 | 5.91e10 |
| 79.9 | 1.19e-8 | 7.36e10 |
| 107.9 | 1.61e-8 | 1.01e11 |
| 197 | 2.94e-8 | 1.84e11 |
| 238 | 3.55e-8 | 2.22e11 |
| Constants: 1 amu = 1.66053906660×10-27 kg; c = 299,792,458 m/s. Per amu: 1 amu ≈ 1.492418×10-10 J ≈ 9.31494×108 eV. | ||
What is Amu To Joules?
Amu to Joules is a conversion from atomic mass units (amu) (a unit of mass) to Joules (J) (a unit of energy) using mass–energy equivalence. Specifically, it converts a mass value to its rest-energy equivalent using Einstein’s equation E = mc2 after converting amu to kilograms.
How to Calculate Amu To Joules?
The following steps outline how to calculate the energy in Joules (J) from a mass in amu.
- First, determine the mass in atomic mass units (amu).
- Convert the mass to kilograms (kg) using 1 amu = 1.66053906660×10-27 kg.
- Use the speed of light in vacuum, c = 299,792,458 m/s (≈ 3.00 × 108 m/s).
- Apply the formula E = mkg × c2 to calculate the energy in Joules (J).
- After inserting the variables and calculating the result, check your answer with a calculator.
Example Problem:
Use the following variables as an example problem to test your knowledge.
mass (m) in atomic mass units (amu) = 5
speed of light (c) in meters per second (m/s) = 299,792,458 (≈ 3.00 × 108)
Solution (rest-energy equivalent): Convert mass to kilograms: m = 5 amu × 1.66053906660×10-27 kg/amu = 8.302695333×10-27 kg. Then E = m c2 ≈ (8.302695333×10-27 kg) × (299,792,458 m/s)2 ≈ 7.46×10-10 J.
