Dalton (Da)
About 1.66054×10⁻²⁷ kg, one twelfth of the mass of a carbon-12 atom. Used for atoms, molecules and proteins.
1 dalton = 1.660539069×10⁻²⁷ kilograms (approximately).
Approximate value. Standards for the dalton varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.
About the dalton
Chemists and biologists quote the mass of a protein as so many kilodaltons, a habit that goes back to John Dalton, who in 1803 suggested taking the lightest atom, hydrogen, as the natural yardstick for atomic weights. The unit itself took other forms for a long time. Around 1903 chemists settled on one sixteenth of an oxygen atom, and in 1960 and 1961 the physics and chemistry unions replaced that with a carbon-12 standard, calling it the unified atomic mass unit with the symbol u.
The name dalton, symbol Da, was proposed by IUPAC in 1993 and endorsed by IUPAP in 2005. It is the same unit as u and is defined as one twelfth of the mass of a free carbon-12 atom at rest in its ground state. The 2022 CODATA value, listed by NIST and in Wikipedia, is 1.66053906892 x 10^-27 kg, with a small uncertainty in the final digits. A helium-4 atom weighs about 4.0026 Da, and the giant protein titin about 3 to 3.7 MDa. The BIPM accepts the unit for use with the SI, and the 2019 redefinition of the kilogram left its definition unchanged.
Sources: Wikipedia: Dalton (unit); NIST CODATA: unified atomic mass unit
Dalton conversion chart
1 dalton expressed in every other weight & mass unit:
| Unit | 1 dalton |
|---|---|
| Kilograms | 1.660539069×10⁻²⁷ |
| Grams | 1.660539069×10⁻²⁴ |
| Metric Tons | 1.660539069×10⁻³⁰ |
| Pounds | 3.660861996×10⁻²⁷ |
| Ounces | 5.857379193×10⁻²⁶ |
| Milligrams | 1.660539069×10⁻²¹ |
| Micrograms | 1.660539069×10⁻¹⁸ |
| Carats | 8.302695345×10⁻²⁴ |
| Stone | 2.614901426×10⁻²⁸ |
| Short Tons | 1.830430998×10⁻³⁰ |
| Long Tons | 1.634313391×10⁻³⁰ |
| Troy Ounces | 5.338757077×10⁻²⁶ |
| Earth Masses | 2.780447857×10⁻⁵² |
| Solar Masses | 8.350837925×10⁻⁵⁸ |
| Quintals | 1.660539069×10⁻²⁹ |
| Grains | 2.562603397×10⁻²³ |
| Drams | 9.371806709×10⁻²⁵ |
| Hundredweight (US) | 3.660861996×10⁻²⁹ |
| Hundredweight (UK) | 3.268626782×10⁻²⁹ |
| Quarters (UK) | 1.307450713×10⁻²⁸ |
| Slugs | 1.137830693×10⁻²⁸ |
| Troy Pounds | 4.448964231×10⁻²⁷ |
| Pennyweights | 1.067751415×10⁻²⁴ |
| Scruples | 1.281301699×10⁻²⁴ |
| Apothecaries' Drams | 4.271005662×10⁻²⁵ |
| Roman Pounds | 5.048765792×10⁻²⁷ |
| Roman Ounces | 6.060361565×10⁻²⁶ |
| Attic Talents | 6.338903149×10⁻²⁹ |
| Attic Minas | 3.803341889×10⁻²⁷ |
| Attic Drachmas | 3.803341889×10⁻²⁵ |
| Obols | 2.282005134×10⁻²⁴ |
| Shekels (biblical) | 1.443947016×10⁻²⁵ |
| Hebrew Talents | 5.765760656×10⁻²⁹ |
| Monme | 4.428104184×10⁻²⁵ |
| Kin | 2.767565115×10⁻²⁷ |
| Kan | 4.428104184×10⁻²⁸ |
| Qian (Chinese) | 3.321078138×10⁻²⁵ |
| Liang (Chinese) | 3.321078138×10⁻²⁶ |
| Jin (Chinese) | 3.321078138×10⁻²⁷ |
| Dan (Chinese) | 3.321078138×10⁻²⁹ |
| Catties (Hong Kong) | 2.745646497×10⁻²⁷ |
| Taels (Hong Kong) | 4.393034395×10⁻²⁶ |
| Tola | 1.423668554×10⁻²⁵ |
| Seers | 1.779585692×10⁻²⁷ |
| Maunds | 4.448964231×10⁻²⁹ |
| Zolotniks | 3.892675531×10⁻²⁵ |
| Funts | 4.054870345×10⁻²⁷ |
| Poods | 1.013717586×10⁻²⁸ |
| Libras (Castilian) | 3.609137868×10⁻²⁷ |
| Arrobas (Spanish) | 1.443655147×10⁻²⁸ |
| Arrobas (Brazilian) | 1.107026046×10⁻²⁸ |
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