iSolveTo← Space & Astronomy
🛰️ Space & Astronomy

Angular Size Calculator

Calculate the apparent angular diameter of an object from its physical diameter and distance.

Free toolGlobal unitsMobile friendly

Enter values

Use the inputs below to calculate the result.

Result

Calculated value—
Uses standard astronomy constants; results are mathematical estimates and should not replace mission-grade ephemerides or navigation data.

How it works

Calculate the apparent angular diameter of an object from its physical diameter and distance.

θ = 2 atan(D / 2d)

How to use this calculator

What to enter

Enter or select the following as requested: Object diameter (km); Distance (km). Follow the units, valid ranges, examples, and options displayed beside each field.

What the result means

The output estimates the stated astronomical quantity from the bodies, distances, masses, speeds, or other parameters entered. Check units, reference frame, and idealized assumptions; real trajectories and observations can involve additional effects.

When to use it

Use this for educational calculations or preliminary comparisons in astronomy and space science. Check the model assumptions before treating the result as a real mission or observational prediction.