18 Seconds to Radians

18" ≈ 8.7266e-5 rad

Calculation: rad = 18" × 4.84814 × 10⁻⁶ ≈ 8.7266e-5 rad

Second to Radian Converter

Choose the type of measurement to convert
Select the source unit to convert from
Select the target unit to convert to
Enter a numeric value or fraction to convert
Sig. Figures:

How wide is 18"?

18 second (0.005 degrees) is comparable to the precision of a telescope crosshair, an almost imperceptible angle.

What does 18" look like?

Illustration of a telescope crosshair reticle
18 second (0.005 degrees) is comparable to the precision of a telescope crosshair, an almost imperceptible angle.

How to Convert Second to Radian

1 second = 4.84814 × 10-6 radians

Radian = Second × 4.84814 × 10-6

Example: 18" × 4.84814 × 10-6 = 8.7266 × 10-5 rad

Reverse Conversion

To convert radians back to seconds:

  • Remember, 1 radian equals 206265 seconds.
  • To convert 8.7266 × 10-5 rad to", multiply 8.7266 × 10-5 x 206265, resulting in 18".

18 " is also equal to:

  • 0.005 degree
  • 0.0055556 gradian
About these units

Second: An arcsecond (second of arc) is 1/60 of an arcminute.It is common in astronomy, surveying, astrometry, and precision optics for high-precision angles.

Radian: The radian (rad) is the SI derived unit of plane angle. It is defined as the angle subtended at the center of a circle by an arc equal in length to the radius.Although mathematically dimensionless, th...

Frequently Asked Questions

How much is 18 seconds in radians?

18 seconds equals 8.7266 × 10⁻⁵ radians. This is calculated by multiplying 18 by the conversion factor 4.84814 × 10⁻⁶.

What does 18 seconds look like in radians?

18 seconds (8.7266 × 10⁻⁵ radians) is a fraction of an arc minute; 3600 arc seconds make one degree.

How do you calculate 18 seconds to radians?

Multiply 18 by the conversion factor 4.84814 × 10⁻⁶. The calculation is 18 × 4.84814 × 10⁻⁶ = 8.7266 × 10⁻⁵ radians. This factor is defined by international measurement standards.

Share This Calculation

18 seconds = 8.72665 × 10⁻⁵ radians
18 seconds = 8.72665 × 10⁻⁵ radians — conversion chart

Nearby Conversions

8 seconds3.879 × 10⁻⁵ radians 9 seconds4.363 × 10⁻⁵ radians 10 seconds4.848 × 10⁻⁵ radians 11 seconds5.333 × 10⁻⁵ radians 12 seconds5.818 × 10⁻⁵ radians 13 seconds6.303 × 10⁻⁵ radians 14 seconds6.787 × 10⁻⁵ radians 15 seconds7.272 × 10⁻⁵ radians 16 seconds7.757 × 10⁻⁵ radians 17 seconds8.242 × 10⁻⁵ radians 19 seconds9.211 × 10⁻⁵ radians 20 seconds9.696 × 10⁻⁵ radians 21 seconds0.0001018 radians 22 seconds0.0001067 radians 23 seconds0.0001115 radians 24 seconds0.0001164 radians 25 seconds0.0001212 radians 26 seconds0.0001261 radians 27 seconds0.0001309 radians 28 seconds0.0001357 radians

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

Also convert Seconds to:

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.