How to use the schwarzschild radius calculator
Find the event horizon radius of a black hole. Enter mass in the field above; the schwarzschild radius is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “how small must the sun be to be a black hole”, “event horizon size”, “calculate schwarzschild radius”, “find schwarzschild radius”.
Formula
Variables
- M — Mass (solar masses)
Worked example
With mass = 1 solar masses, the calculator gives schwarzschild radius ≈ 2.953339 km.
Frequently asked questions
What is the schwarzschild radius calculator used for?
Find the event horizon radius of a black hole. It helps with questions such as “how small must the sun be to be a black hole”, “event horizon size”, “calculate schwarzschild radius”.
What is the formula for the schwarzschild radius calculation?
Schwarzschild radius (km) = 2 × GCONST × M × MSUN / CLIGHT^2 / 1000. Here M is mass (solar masses).
What inputs do I need for the schwarzschild radius (black hole) calculator?
You need mass in solar masses. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the schwarzschild radius calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the schwarzschild radius result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.