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) = 1.660539e-9 Femtogram (fg).
| Atomic Mass Unit (u) | Femtogram (fg) |
|---|---|
| 0.1 | 1.660539e-10 |
| 0.5 | 8.302695e-10 |
| 1 | 1.660539e-9 |
| 2 | 3.321078e-9 |
| 5 | 8.302695e-9 |
| 10 | 1.660539e-8 |
| 25 | 4.151348e-8 |
| 50 | 8.302695e-8 |
| 100 | 1.660539e-7 |
| 500 | 8.302695e-7 |
| 1000 | 0.000001660539067 |
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 femtogram is a unit of mass equal to 10⁻¹⁵ grams or 10⁻¹⁸ kilograms — one quadrillionth of a gram.
1 fg = 10⁻¹⁵ g = 10⁻¹⁸ kg = 1,000 ag.
To convert fg to kg: multiply by 10⁻¹⁸. To convert fg to pg: divide by 1,000.
Expressing the mass of individual bacterial cells (~100 fg for E. coli) and subcellular components.
A single E. coli bacterium has a mass of about 600–700 fg. A single mitochondrion is roughly 1 fg.
Mixing up fg (femtogram) with fm (femtometer) — one is mass, the other is length.
A bacterium weighs ~500 fg — this gives you a tangible anchor for the femtogram scale.



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