Seismic Magnitude Converter

Convert seismic magnitude to energy released (Joules, TNT equivalent) and Modified Mercalli Intensity (MMI).

Inputs

Earthquake Magnitude

Magnitude Scale

Tab to move between fields

Results

Magnitude

Energy Released

1,995,000,000,000 J

MMI (Mercalli Intensity)

ScaleRichter (ML)

TNT Equivalent476.88 tons

Intensity DescriptionVery strong

Energy Ratio vs M4.031.62×

Approx. Global/Year1,300

How to Use This Calculator

Enter the Earthquake Magnitude value from seismograph recordings.
Select the Magnitude Scale: Richter (ML) for local earthquakes or Moment Magnitude (Mw) for global events.
Review Energy Released in Joules and the TNT Equivalent to grasp the scale of energy.
Check the Modified Mercalli Intensity (MMI) and its description to understand felt shaking severity.
Use Energy Ratio vs M4.0 to appreciate the logarithmic nature of the magnitude scale.

How the result changes with Earthquake Magnitude

Earthquake Magnitude	Magnitude	Energy Released	MMI (Mercalli Intensity)
1	1	1,995,000 J	1
3.5	3.5	11,220,000,000 J	4
6.5	6.5	354,800,000,000,000 J	9
9	9	1,995,000,000,000,000,000 J	12

What each input means

Earthquake Magnitude: Earthquake magnitude on the selected scale. Each whole number increase represents ~31.6x more energy.
Magnitude Scale: Richter scale is used for local events; Moment magnitude is preferred for large earthquakes.

How this is calculated

Formula

E = 10^(1.5M + 4.8) Joules

Worked example, using the default values

Identify Input Parameters
Earthquake Magnitude = 5, Magnitude Scale = 1 = 2 input(s) provided
Calculate Magnitude
Magnitude = m
5 = 5
Calculate Energy Released
Energy Released = Number(energyJoules.toExponential(3))
1995000000000 = 1995000000000
Calculate MMI
MMI
7 = 7
Calculate Scale
Richter (ML) = Richter (ML)
Calculate TNT Equivalent
TNT Equivalent
476.88 = 476.88

Engine last updated July 21, 2026. Checked against 3 independently-derived tests — how we verify calculators.

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