Arcsecond (″)
Exactly 1/3600 of a degree.
What is an arcsecond?
- Symbol
- ″
- Quantity
- Angle
- Unit system
- SI-accepted
- Definition
- Exactly 1/3600 of a degree.
- Exact
- Yes, the value is exact by definition
- Source
- SI Brochure, 9th edition (BIPM, 2019)
Common applications
Used in astronomy for the apparent size of stars and planets, and in precise surveying.
Arcsecond in other angle units
- 1 ″ ≈ 0.000004848136811 radRadian
- 1 ″ ≈ 0.004848136811 mradMilliradian
- 1 ″ ≈ 0.0002777777778 °Arcsecond to Degree converter
- 1 ″ ≈ 0.01666666667 ′Arcminute
- 1 ″ ≈ 0.0003086419753 gradGradian (gon)
- 1 ″ ≈ 7.716049383e-7 revTurn (revolution)
Arcsecond quick reference
| Arcsecond | Degree | Radian | Milliradian |
|---|---|---|---|
| 1 ″ | ≈ 0.0002777777778 ° | ≈ 0.000004848136811 rad | ≈ 0.004848136811 mrad |
| 10 ″ | ≈ 0.002777777778 ° | ≈ 0.00004848136811 rad | ≈ 0.04848136811 mrad |
| 100 ″ | ≈ 0.02777777778 ° | ≈ 0.0004848136811 rad | ≈ 0.4848136811 mrad |
| 1000 ″ | ≈ 0.2777777778 ° | ≈ 0.004848136811 rad | ≈ 4.848136811 mrad |
Where the arcsecond fits
The next larger angle unit is the arcminute (′). 1 ″ ≈ 0.01666666667 ′, and 1 ′ = 60 ″.
Frequently asked questions
- How many degrees are in one arcsecond?
- One arcsecond ≈ 0.0002777777778 ° (degrees).
- How many radians are in one arcsecond?
- One arcsecond ≈ 0.000004848136811 rad (radians).
- How many milliradians are in one arcsecond?
- One arcsecond ≈ 0.004848136811 mrad (milliradians).