Kilograms to Daltons (kg to Da)
1 kilogram equals 6.022140754×10²⁶ daltons (rounded).
How to convert kilograms to daltons
To convert kilograms to daltons, multiply the number of kilograms by 6.022140754×10²⁶. The factor is rounded to 10 significant digits. To go the other way, multiply daltons by 1.660539069×10⁻²⁷ (rounded).
daltons = kilograms × 6.022140754×10²⁶
Example: 10 kilograms = 6.022140754×10²⁷ daltons.
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 these units
Kilogram (kg)
The SI base unit of mass. Since 2019 it is defined by fixing the value of the Planck constant, replacing the old platinum-iridium cylinder in Paris.
Oddly for a base unit, the kilogram began life as a derived one. In 1793 revolutionary France defined the grave as the mass of one litre of water, and a decree of 1795 then replaced it with the kilogramme, a name built from the Greek khilioi (a thousand) and gramma, a Late Latin word for a small weight. In 1799 a platinum cylinder, the Kilogramme des Archives, became the physical standard, matching a cubic decimetre of water at its densest, around 4 degrees Celsius. In 1889 the metric community adopted a platinum-iridium cylinder made in 1879, the International Prototype of the Kilogram, nicknamed Le Grand K.
The kilogram is still the only SI base unit with a prefix in its name. Because SI forbids stacked prefixes, a millionth of a kilogram is a milligram rather than a microkilogram, so every mass prefix is attached to the gram. Calibrating every national standard against one object in a vault near Paris meant that all of them drifted relative to it, so in November 2018 member states voted to tie the kilogram to a fixed value of the Planck constant. The change took effect on 20 May 2019. Day to day nothing shifted, but the definition no longer depends on a single piece of metal.
The kilogram is the reference unit for weight & mass on this site.
Sources: NIST: Kilogram introduction (SI redefinition); Wikipedia: Kilogram
Dalton (Da)
About 1.66054×10⁻²⁷ kg, one twelfth of the mass of a carbon-12 atom. Used for atoms, molecules and proteins.
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.
1 dalton = 1.660539069×10⁻²⁷ kilograms (approximately).
Sources: Wikipedia: Dalton (unit); NIST CODATA: unified atomic mass unit
Related conversions
- Daltons to kilograms (reverse)
- Kilograms to grams
- Kilograms to metric tons
- Kilograms to pounds
- Kilograms to ounces
- Kilograms to milligrams
- Kilograms to micrograms
- Kilograms to carats
- Kilograms to stone
- Kilograms to short tons
- Kilograms to long tons
- Kilograms to troy ounces
- Kilograms to Earth masses
- Grams to daltons
- Metric tons to daltons
- Pounds to daltons
- Ounces to daltons
See all weight & mass units.