21 Arc Seconds to Radians

21" ≈ 0.00010181 rad

Calculation: rad = 21" × 4.84814 × 10⁻⁶ ≈ 0.00010181 rad

Arc Second to Radian Converter

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Sig. Figures:

How wide is 21"?

21 arc second (0.006 degrees) is comparable to the precision of a telescope crosshair, an almost imperceptible angle.

What does 21" look like?

Illustration of a telescope crosshair reticle
21 arc second (0.006 degrees) is comparable to the precision of a telescope crosshair, an almost imperceptible angle.

How to Convert Arc Second to Radian

1 arc second = 4.84814 × 10-6 radians

Radian = Arc Second × 4.84814 × 10-6

Example: 21" × 4.84814 × 10-6 = 0.00010181 rad

Reverse Conversion

To convert radians back to arc seconds:

  • Remember, 1 radian equals 206265 arc seconds.
  • To convert 0.00010181 rad to", multiply 0.00010181 x 206265, resulting in 21".

21 " is also equal to:

  • 0.0058333 degree
  • 0.0064815 gradian

Frequently Asked Questions

How much is 21 arc seconds in radians?

21 arc seconds equals 0.00010181 radians. This is calculated by multiplying 21 by the conversion factor 4.84814 × 10⁻⁶.

What does 21 arc seconds look like in radians?

21 arc seconds equals 0.00010181 radians, a conversion used in navigation, trigonometry, and engineering design.

How do you calculate 21 arc seconds to radians?

Multiply 21 by the conversion factor 4.84814 × 10⁻⁶. The calculation is 21 × 4.84814 × 10⁻⁶ = 0.00010181 radians. This factor is defined by international measurement standards.

Share This Calculation

21 arc seconds = 0.000101811 radians
21 arc seconds = 0.000101811 radians — conversion chart

Nearby Conversions

11 arc seconds5.333 × 10⁻⁵ radians 12 arc seconds5.818 × 10⁻⁵ radians 13 arc seconds6.303 × 10⁻⁵ radians 14 arc seconds6.787 × 10⁻⁵ radians 15 arc seconds7.272 × 10⁻⁵ radians 16 arc seconds7.757 × 10⁻⁵ radians 17 arc seconds8.242 × 10⁻⁵ radians 18 arc seconds8.727 × 10⁻⁵ radians 19 arc seconds9.211 × 10⁻⁵ radians 20 arc seconds9.696 × 10⁻⁵ radians 22 arc seconds0.0001067 radians 23 arc seconds0.0001115 radians 24 arc seconds0.0001164 radians 25 arc seconds0.0001212 radians 26 arc seconds0.0001261 radians 27 arc seconds0.0001309 radians 28 arc seconds0.0001357 radians 29 arc seconds0.0001406 radians 30 arc seconds0.0001454 radians 31 arc seconds0.0001503 radians

For general conversions between arc seconds and radians, see the arc seconds to radians converter.

Conversion factors verified against BIPM, ISO 80000-3 1 turn = 2π rad = 360° (exact, ISO 80000-3). Last reviewed: March 2026
Adilson Fernandes By Adilson Fernandes
Tiago Fernandes Reviewed by Tiago Fernandes

All unit conversions on CoolConversion use conversion factors defined or documented by internationally recognised standards bodies (such as ISO and NIST), including both SI and non-SI units.