Astronomy Schwarzschild Radius

A GR event-horizon scale for study problems. Not a Kerr (spinning) calculator.

Rs = 2GM/c² in meters.

Tip: Enter a realistic “Mass M (kg)” value, then compare the Astronomy Schwarzschild Radius result to the worked example on this page.

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The Schwarzschild radius is 2GM/c² for a non-rotating black hole teaching model.

Enter mass in kilograms. Uses G = 6.6743×10⁻¹¹ and c = 299792458 m/s.

Mass in kilograms

Schwarzschild Radius

Understanding Astronomy Schwarzschild Radius

How we calculate. Rs = 2GM/c² in meters. The form uses the same arithmetic as the worked examples on this page. See our methodology and accuracy policy.

Real-world scenario: M = 1.989×10³⁰ kg (≈1 M☉). Use those inputs in the Astronomy Schwarzschild Radius form to verify the on-page formula.

What is Astronomy Schwarzschild Radius?

A GR event-horizon scale for study problems. Not a Kerr (spinning) calculator.

  • Mass in kg
  • Non-spinning model
  • Result in meters

The Formula

Schwarzschild Radius
Rs = 2 G M ÷ c²

Worked Example

Scenario: M = 1.989×10³⁰ kg (≈1 M☉).
Step 1: 2GM/c² ≈ 2950
Answer: Schwarzschild radius is approximately 2950 m.

Common Use Cases

  • Homework: black-hole scales
  • Study: compare to stellar radii
  • Lab: constant drills

Pro Tips

  • Convert solar masses → kg
  • Not Kerr metric
  • Educational only

Limitations: Astronomy Schwarzschild Radius results are educational astronomy study aids—not navigation, mission planning, or professional observing advice. Confirm constants and units with your textbook or instructor.

FAQ

Does spin change Rs?

Yes in Kerr geometry—this page is the non-spinning Schwarzschild teaching formula only.

Same as escape-velocity radius?

Related idea; this page computes Rs = 2GM/c² directly.

Authoritative References

For astronomy study concepts, consult:

  • OpenStax Astronomy — free textbook reference
  • NASA — mission and outreach context
  • IAU — astronomical constants and naming