What does each step on the Richter scale mean?

The Richter scale is logarithmic. Each whole-number step represents about 10 times more ground shaking amplitude and roughly 31.6 times more energy released. A magnitude 7.0 quake releases about 31.6 times more energy than a 6.0 quake.

Is the Richter scale still used today?

Modern seismologists primarily use the Moment Magnitude Scale (Mw), which is more accurate for large earthquakes. However, for moderate quakes the two scales give very similar values, and "Richter scale" remains the common public term.

What is the energy ratio formula used here?

Energy ratio = 10^(1.5 × ΔM), where ΔM is the difference between the two magnitudes. This comes from the empirical relation log₁₀(E) ≈ 1.5 × M + 4.8.

What magnitude is considered dangerous?

Quakes below 2.0 are usually not felt. Magnitude 3–4 may be felt but rarely cause damage. From magnitude 5.0 upward damage becomes possible, and above 7.0 earthquakes can cause widespread destruction.

Can I enter decimal magnitudes?

Yes. Real-world seismograms produce fractional values such as 6.8 or 9.1. The calculator accepts any value between 0.0 and 10.0.

Richter Magnitude Calculator

Name: Richter Magnitude Calculator
Availability: InStock
Author: Nham Vu

Compare two earthquake magnitudes on the Richter scale — see the energy ratio and descriptive categories with real-world impact.

Enter Magnitudes

Earthquake A — Magnitude

Earthquake B — Magnitude

Historical Examples

Earthquake A

7.0

Earthquake B

5.0

Energy Comparison

—

times more energy

B A

Bar widths are proportional (log scale capped at 100x)

Richter Scale Reference

Summary

Compare two earthquake magnitudes on the Richter scale — see the energy ratio and descriptive categories with real-world impact.

How it works

Enter the two earthquake magnitudes you want to compare (decimals like 6.8 or 9.1 are accepted).
The tool computes the energy ratio 10^(1.5 × (M1 − M2)), derived from the relationship E ∝ 10^(1.5 × M).
Each magnitude is assigned a descriptive category from standard USGS ranges (minor, moderate, strong, major, great).
The result shows how many times more energy the larger quake releases, plus the impact category for each.

Use cases

Understand how much more destructive a magnitude 7.0 quake is versus a 5.0.
Quickly look up the category (minor, moderate, strong, major, great) for any felt quake.
Educate students on the logarithmic nature of the Richter scale.
Compare historical earthquakes (e.g., 1906 San Francisco M7.9 vs 2011 Tohoku M9.1).

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu