Declination to Decimal Degrees Converter

About this calculator

Astronomical declination — a celestial object’s angular distance north or south of the celestial equator — is traditionally written in degrees, arcminutes and arcseconds (DMS), mirroring how latitude was once expressed. Converting it to a single signed decimal number uses decimal = sign × (D + M/60 + S/3600), where the sign is negative for southern declinations.

Star catalogs, planetarium software and telescope mounts increasingly work with plain decimal degrees because they’re easier to compute with — sorting, averaging and coordinate transforms all become simple arithmetic instead of sexagesimal bookkeeping. Amateur and professional astronomers use this conversion when entering a star’s equatorial coordinates (right ascension and declination) into go-to telescope controllers, imaging software, or astrometry scripts that expect decimal input.