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AMU to Grams Converter
↔ Convert g to amu instead

Common Conversions

amu g
1 1.661e-24
2 3.321e-24
4 6.642e-24
12 1.993e-23
16 2.657e-23
18.015 2.992e-23
28 4.649e-23
32 5.314e-23
44 7.306e-23
56 9.299e-23
197 3.271e-22

Why this conversion matters in chemistry

The atomic mass unit exists because single atoms are absurdly small, and writing their masses in grams means dragging a factor of 10⁻²⁴ through every calculation. The amu (also written as u or as the dalton, Da) is scaled so that a single carbon-12 atom weighs exactly 12 u. Multiply by 1.66054 × 10⁻²⁴ g/amu and you get the absolute mass in grams — 12 u becomes 1.993 × 10⁻²³ g, a number that never feels intuitive. That's the whole point: the amu was invented so we could talk about atomic masses using numbers that fit on a periodic table.

Formula

g = amu × 1.66054 × 10⁻²⁴

Worked Examples

1 amu = 1.66054 × 10⁻²⁴ g

About the mass of one proton or neutron. The base unit in atomic-scale mass work.

12 amu = 1.99265 × 10⁻²³ g

A single carbon-12 atom. The definition point — carbon-12 is exactly 12 u by convention.

18.015 amu = 2.9915 × 10⁻²³ g

One water molecule, to the precision you usually see it reported at.

6.022 × 10²³ amu = 1.000 g

Avogadro's number of amu. The elegant coincidence that pins the mole-based chemistry we actually do to the atomic-scale masses we talk about.

Frequently Asked Questions

How do I convert amu to grams?
Multiply by 1.66054 × 10⁻²⁴. So 12 amu (one carbon-12 atom) becomes 1.993 × 10⁻²³ g. The factor is the reciprocal of Avogadro's number, expressed in grams — a neat bit of SI bookkeeping that makes the bridge from amu to moles work out.
How are amu and moles connected?
Deliberately. The amu was defined so that a mole of particles each weighing X amu has a mass of exactly X grams. A mole of carbon-12 atoms, with 12 amu each, weighs 12 g. It's the definitional trick that makes the periodic table's atomic masses double as molar masses without any conversion.
What's 1 amu in grams?
1.66054 × 10⁻²⁴ g — which is 1 divided by Avogadro's number. If you can keep Avogadro's number in your head (6.022 × 10²³), you can always reconstruct the factor on demand.
Is amu the same as dalton?
Yes. The unified atomic mass unit (u, sometimes still written amu) and the dalton (Da) are identical — same value, different notation. Biochemistry tends to prefer daltons and kilodaltons for proteins and nucleic acids; physics and inorganic chemistry tend to stick with u.