Instant · Precise · Universal
34 units available
6 categories total
To convert u to kg: multiply by 1.6605390666 × 10⁻²⁷. To convert u to MeV/c²: multiply by 931.494.
1 u = 1.6605390666 × 10⁻²⁷ kg = 1/Nₐ grams ≈ 931.494 MeV/c².
For example, 1 Atomic Mass Unit (u) = 8.350838e-58 Sun's Mass (M☉).
| Atomic Mass Unit (u) | Sun's Mass (M☉) |
|---|---|
| 0.1 | 8.350838e-59 |
| 0.5 | 4.175419e-58 |
| 1 | 8.350838e-58 |
| 2 | 1.670168e-57 |
| 5 | 4.175419e-57 |
| 10 | 8.350838e-57 |
| 25 | 2.087709e-56 |
| 50 | 4.175419e-56 |
| 100 | 8.350838e-56 |
| 500 | 4.175419e-55 |
| 1000 | 8.350838e-55 |
The atomic mass unit (unified) is defined as 1/12 the mass of a carbon-12 atom, approximately 1.661 × 10⁻²⁷ kilograms.
1 u = 1.6605390666 × 10⁻²⁷ kg = 1/Nₐ grams ≈ 931.494 MeV/c².
To convert u to kg: multiply by 1.6605390666 × 10⁻²⁷. To convert u to MeV/c²: multiply by 931.494.
Molecular weight calculations, mass spectrometry data interpretation, and chemical stoichiometry.
A proton has a mass of ~1.007 u, a neutron ~1.009 u. The discrepancy from 1.000 reflects nuclear binding energy.
Confusing 'amu' (the old, obsolete term) with 'u' (the unified standard). Also, forgetting that 1 u ≠ 1 gram.
Think of u as 'approximately the mass of one proton or neutron.' Carbon-12 = 12 u exactly (by definition).
The solar mass is the mass of the Sun, approximately 1.989 × 10³⁰ kilograms — about 333,000 times the mass of Earth.
M☉ = 1.98847 × 10³⁰ kg ≈ 333,000 M⊕ ≈ 1,048 M_Jupiter.
To convert solar masses to kg: multiply by 1.98847 × 10³⁰.
Expressing stellar masses: Betelgeuse ≈ 15 M☉, Sirius ≈ 2 M☉, a typical neutron star ≈ 1.4 M☉.
The Sun loses about 5 million tonnes per second through nuclear fusion (E=mc²), but that's only 10⁻¹³ M☉ per year.
The Sun is losing mass continuously through radiation and solar wind — its mass is not quite constant over billions of years.
Almost everything in astronomy uses solar masses: stars (0.1–100 M☉), galaxies (10⁹–10¹² M☉), black holes (3–10⁹ M☉).



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