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Earthquake Energy Calculator
Convert earthquake magnitude into joules and TNT equivalent, compare it to bombs and eruptions, and compare two magnitudes side by side.
This works right here on your device — nothing gets sent out.
Moment magnitude (Mw), the modern standard scale used for magnitude ≥ ~3.5. Accepts −2 to 10.
Radiated energy
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TNT equivalent
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Roughly equivalent to
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How Earthquake Energy Calculator works
- Enter a moment magnitude (Mw), drag the slider, or load a known historical earthquake from the dropdown.
- The calculator applies the Gutenberg-Richter relation to convert magnitude into radiated energy in joules, then converts that into a TNT equivalent and a magnitude classification.
- The "Roughly equivalent to" panel scales that energy against reference events — a lightning bolt, the Hiroshima and Nagasaki bombs, Krakatoa, and Tsar Bomba — so the number is easier to picture.
- Switch to "Compare two magnitudes" to see the energy ratio and seismogram amplitude ratio between any two earthquakes.
- Use "Copy summary" to grab a plain-text line with the magnitude, energy, and TNT equivalent.
The formula
Radiated seismic energy is estimated from moment magnitude using the Gutenberg-Richter energy-magnitude relation:
log₁₀(E) = 1.5 × M + 4.8 (E in joules)
Comparing two magnitudes M₁ and M₂, the energy ratio is 10^(1.5 × ΔM) and the seismogram amplitude ratio is 10^(ΔM), where ΔM = M₂ − M₁.
FAQ
What formula converts earthquake magnitude to energy?
The Gutenberg-Richter energy-magnitude relation: log₁₀(E) = 1.5 × M + 4.8, where E is radiated energy in joules and M is moment magnitude (Mw). Each whole-number increase in magnitude means about 31.6× more energy — a difference of 2.0 in magnitude means 1,000× more energy.
Why does a 1-point jump in magnitude mean 31.6× the energy?
Because energy scales with magnitude raised through the 1.5 exponent in the formula: 10^1.5 ≈ 31.6. Magnitude itself is logarithmic in ground-motion amplitude (each point is 10× the amplitude), but energy grows faster than amplitude, which is why the energy multiplier per magnitude point is larger than the amplitude multiplier.
Is this the same as the Richter scale?
Richter (“ML”) was the original 1930s scale and saturates — it underestimates very large earthquakes. Moment magnitude (Mw), used here, is the modern standard reported by USGS and other seismological agencies for anything above about magnitude 3.5-4, and is what “magnitude” refers to in virtually all recent earthquake reporting.
Does the energy number tell me how much damage an earthquake caused?
Not directly. This is the total energy radiated at the source. Actual damage depends heavily on depth, distance from population centers, local soil conditions, and building construction — a deep magnitude 7 offshore can cause far less damage than a shallow magnitude 6 under a city.
Where do the TNT and reference-event comparisons come from?
1 ton of TNT is defined as 4.184 gigajoules. The reference yields (Hiroshima/Nagasaki bombs, Tsar Bomba, Krakatoa) are widely published historical estimates used for scale, not this tool’s own measurements — treat them as order-of-magnitude comparisons.
How we compare
| Feature | Online Tool Store | Omni Calculator | Gelogia |
|---|---|---|---|
| Magnitude → energy (joules) and TNT equivalent | Included | Included | Included |
| Reference-event comparisons (bombs, eruptions, lightning) | Included | Not included | Included |
| Compare two magnitudes: energy and amplitude ratio | Included | Included | Not included |
| Full magnitude classification table with live highlight | Included | Not included | Summary table, not interactive |
| Preset picker for well-known historical earthquakes | Included | Not included | Not included |
| Runs fully in your browser, nothing uploaded | Included | Included | Included |
| Copy a plain-text result summary | Included | Share-link based | Not included |
Choose Earthquake Energy Calculator when you want both a quick single-magnitude readout and a side-by-side comparison of two earthquakes, with historical presets and reference-event comparisons in one place.