How much bigger is one whole magnitude step?

A one-unit increase corresponds to 10 times the recorded seismic-wave amplitude and about 31.6 times the energy release. Those are different quantities, so this calculator reports both.

Does this calculate Richter magnitude from a seismogram?

No. It compares two magnitude values you already have. Calculating local magnitude (ML) from a seismogram requires measured amplitude plus instrument and distance corrections.

Is Richter magnitude the same as moment magnitude?

Not exactly. “Richter scale” usually refers to local magnitude (ML), developed for nearby Southern California earthquakes. Moment magnitude (Mw) is now generally used for large earthquakes. The comparison formulas here operate on the two supplied magnitude values; check the source scale before comparing catalog values.

Can magnitude be negative?

Yes. Because earthquake magnitude is logarithmic, instruments can record very small events with negative magnitudes. This calculator accepts values from −3.0 to 10.0, matching the range used by the USGS comparison calculator.

Can magnitude alone predict damage?

No. Damage and felt intensity also depend on distance, depth, local ground conditions, building construction, and other factors. This tool intentionally does not estimate damage or casualties.

Earthquake Magnitude Comparison

Compare two earthquake magnitudes and see both standard logarithmic results: the seismic-wave amplitude ratio and the approximate energy ratio.

Compare reported magnitudes

Earthquake A magnitude

Earthquake B magnitude

Accepted range: −3.0 to 10.0. Decimals are supported.

Formula examples

Magnitude difference

1.0

Earthquake A has the larger reported magnitude.

Wave amplitude

10×

Difference in recorded seismic-wave amplitude: 10^ΔM.

Approximate energy

31.6×

Difference in energy release: 10^1.5ΔM.

Estimated energy for each magnitude

Earthquake A · M 7.0

1.995 × 10¹⁵ J

Earthquake B · M 6.0

6.310 × 10¹³ J

Approximation: log₁₀ E(J) = 1.5M + 4.8. It is useful for scale comparison, not a site-specific shaking or damage forecast.

Method and limitations

Magnitude is one value for an earthquake; felt intensity varies by location. A one-unit magnitude increase means 10× recorded amplitude and approximately 31.6× energy.

“Richter” commonly refers to local magnitude (ML). Modern catalogs generally use moment magnitude (Mw) for large earthquakes. Compare values from the same scale when precision matters.

This calculator does not predict damage. Distance, depth, geology and construction all affect observed shaking and losses.

Summary

Compare two earthquake magnitudes and see both standard logarithmic results: the seismic-wave amplitude ratio and the approximate energy ratio.

How it works

Enter two reported magnitudes from −3.0 through 10.0. Negative magnitudes are valid for very small recorded events.
The calculator finds the absolute magnitude difference ΔM and calculates the amplitude ratio as 10^ΔM.
It calculates the approximate energy ratio as 10^(1.5 × ΔM), and estimates each event’s energy with log₁₀ E(J) = 1.5M + 4.8.
Use the two results separately: “times bigger” refers to recorded wave amplitude, while “times stronger” commonly refers to energy release.

Use cases

Compare the wave amplitude of two reported earthquake magnitudes.
Compare the approximate energy released by two earthquakes.
Demonstrate why a one-unit magnitude increase means 10× amplitude but about 31.6× energy.
Explore small negative magnitudes and large reported magnitudes with the same logarithmic formulas.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu