Arcseconds to radians
Type a value in arcseconds to see it in radians straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the arcseconds box.
- Read the result in radians as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
rad = " × 0.000004848136811
Multiply the value in arcseconds by 0.000004848136811 to get radians.
Example
To convert 25 " to radians: 25 × 0.000004848136811 = 0.000121203 rad.
Conversion table
| Arcseconds (") | Radians (rad) |
|---|---|
| 1 | 0.00000484814 |
| 2 | 0.00000969627 |
| 3 | 0.0000145444 |
| 5 | 0.0000242407 |
| 10 | 0.0000484814 |
| 20 | 0.0000969627 |
| 25 | 0.000121203 |
| 50 | 0.000242407 |
| 100 | 0.000484814 |
| 250 | 0.00121203 |
| 500 | 0.00242407 |
| 1,000 | 0.00484814 |
About the units
- Arcsecond
- An arcsecond is 1/60 of an arcminute, or 1/3600 of a degree, used in astronomy and precise coordinates.
- Radian
- The radian is the SI unit of angle: the angle subtended by an arc equal in length to the radius. It equals 180/π degrees, about 57.2958 degrees.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many radians are in one arcsecond?
1 " = 0.00000484814 rad exactly.
How do I convert arcseconds to radians?
Use rad = " × 0.000004848136811. For example, 25 " = 0.000121203 rad.
How many arcseconds are in one radian?
1 rad = 206,265 ".
Why does my calculator give a strange answer for sine?
It is probably set to radians (RAD) while you are entering degrees. The sine of 30 degrees is 0.5, but the sine of 30 radians is about -0.988, so switch to DEG first.
What is the difference between MOA and MIL on a rifle scope?
MOA is an arcminute, 1/60 of a degree, while a MIL is a milliradian, about 3.438 MOA. At 100 meters a 0.1 MIL click moves impact 1 cm, and 1 MOA moves it about 2.9 cm.