Angular Size Calculator
Fill in the values and the answer updates as you type.
How the Angular Size Calculator works
Angular size = 2 × arctan(diameter ÷ (2 × distance)). The result is in degrees, then multiplied by 60 for arcminutes and 3,600 for arcseconds. The Moon is about 0.52° across and the Sun about 0.53°, which is why total solar eclipses are possible. Use the same unit for the diameter and distance. Example: with Object diameter 3474 km and Distance to the object 384400 km, the result is Angular size (degrees) = 0.52; Angular size (arcminutes) = 31.07; Angular size (arcseconds) = 1,864.
Inputs and results
The Angular Size Calculator takes 2 inputs and gives 3 results.
What you enter
- Object diameter (km) — starts at 3474.
- Distance to the object (km) — starts at 384400.
What you get
- Angular size (degrees)
- Angular size (arcminutes)
- Angular size (arcseconds)
Example: Angular Size Calculator with the starting values
With object diameter 3474 km and distance to the object 384400 km, the calculator returns:
| Angular size (degrees) | 0.52 |
|---|---|
| Angular size (arcminutes) | 31.07 |
| Angular size (arcseconds) | 1,864 |
Change any value above and the results update straight away.
Angular Size Calculator FAQ
How do I use the Angular Size Calculator?
Enter object diameter and distance to the object in the fields, then read angular size (degrees), angular size (arcminutes) and angular size (arcseconds) in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Angular Size Calculator calculate?
How large an object appears in the sky from its size and distance. It returns angular size (degrees), angular size (arcminutes) and angular size (arcseconds) from the 2 values you provide.
What values does the Angular Size Calculator start with?
It opens with object diameter 3474 km and distance to the object 384400 km so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Angular Size Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Angular Size Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.