Right Ascension to Degrees Converter

Enter right ascension as hours, minutes and seconds to convert to degrees.

Result

101.29°

How it is calculated

The tool turns the three fields into a single number of hours and multiplies by 15: degrees = 15 × (h + m ÷ 60 + s ÷ 3600). Here h is hours, m is minutes of time and s is seconds of time. The factor 15 is 360° divided by 24 hours. Minutes and seconds may be left empty and are then treated as 0; hours are required. Negative values give no result. The engine does not wrap or limit the input, so 25 hours and 75 minutes simply give 393.75°, beyond a full circle. The answer is shown with two decimals and a degree sign.

Worked example

Convert a right ascension of 6 h 45 m 9 s. Minutes as hours: 45 ÷ 60 = 0.75. Seconds as hours: 9 ÷ 3600 = 0.0025. Total: 6 + 0.75 + 0.0025 = 6.7525 h. Multiply by 15: 6.7525 × 15 = 101.2875, displayed as 101.29°. The two-decimal display rounds the value, so keep the unrounded figure if you chain further calculations.

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Common mistakes

  • Treating the minutes and seconds as arcminutes and arcseconds. In right ascension they are minutes and seconds of time, so one minute is 15 arcminutes, not 1.
  • Typing a declination (for example +41° 16′) into these fields. Declination is already in degrees and needs no ×15 conversion.
  • Entering a decimal-hour value in the hours field and then also filling minutes. Put 6.75 in hours with the others empty, or use 6 h 45 m, not both.
  • Typing a negative RA to mean west or before zero. Right ascension runs 0 to 24 h and the tool returns nothing for negative values; add 24 h first.
  • Expecting values over 24 h to wrap back into 0°–360°. The tool does not wrap them.

About this calculator

Right ascension (RA) is the celestial equivalent of longitude, used in the equatorial coordinate system to locate stars and deep-sky objects. Astronomers traditionally express it in hours, minutes and seconds (since the full 360° circle corresponds to the 24-hour rotation of the sky), which means 1 hour of RA equals exactly 15 degrees (360° ÷ 24h) — the conversion this calculator performs, along with the proportional scaling of minutes and seconds.

Converting RA into decimal degrees is a routine step whenever you need to feed coordinates into telescope-pointing software, plate-solving tools, or any calculation (like angular separation between two objects) that requires both RA and declination expressed in the same degree-based units.

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