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Astronomy Calculators

Angular Size Calculator

Apparent angular size of an object from its real size and distance, in degrees, arcminutes and arcseconds.

Enter values

Results update as you type.

Result

Angular size

0.517805 °

Arcminutes
31.0683
Arcseconds
1,864.1
Compared to the full Moon
0.9992 ×

About the Angular Size Calculator

Apparent angular size of an object from its real size and distance, in degrees, arcminutes and arcseconds.

Also known as: apparent size, angular diameter, arcseconds calculator, how big does it look.

How to use this calculator

  1. Enter solve for.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

θ = 2·arctan(size / 2d)

Worked example

Using the values pre-filled in the calculator above:

  • Solve for: Angular size
  • Actual size = 3,474 km
  • Distance = 384,400 km

the calculator returns:

  • Angular size: 0.517805 °
  • Arcminutes: 31.0683
  • Arcseconds: 1,864.1
  • Compared to the full Moon: 0.9992 ×