Earthquake Calculator — Magnitude, Energy & Comparison
Enter an earthquake magnitude to see the energy released in joules and its USGS severity category. Add a reference magnitude to instantly find how many times stronger the two quakes are in amplitude and energy.
Moderate — widely felt
How does this calculator work?
Each magnitude step means 10× more ground shaking and ~31.6× more energy (log₁₀ E = 1.5M + 4.8 joules). A M5 releases ~2.8 GJ; a M7 releases ~1,000× more energy than a M5. Compare any two magnitudes to get exact amplitude and energy ratios on the logarithmic scale.
Formula
How this is calculated
The Richter scale (and its modern replacement, moment magnitude Mw) is logarithmic: each whole-number step means 10 times greater ground motion amplitude and about 31.6 times more energy released. The calculator uses the Gutenberg–Richter energy relation, log₁₀(E) = 1.5M + 4.8, to convert any magnitude to total seismic energy in joules. A magnitude 5 quake releases roughly 2.8 GJ — comparable to a small nuclear device — while a magnitude 9 releases about 32 EJ.
The comparison feature computes two ratios for any pair of magnitudes. The amplitude ratio (10^ΔM) reflects the peak ground shaking — important for structural damage assessments. The energy ratio (10^(1.5·ΔM)) captures total seismic energy; a difference of just 2 magnitude units means 1,000 times more energy released. This non-linear scaling explains why a M7 earthquake is thousands of times more destructive than a M5.
Severity categories follow USGS guidelines: micro (<2) are not felt; minor (2–3.9) rarely felt; light (4–4.9) noticeable indoors; moderate (5–5.9) widely felt; strong (6–6.9) potentially destructive; major (7–7.9) serious damage over wide areas; great (≥8) total devastation. The Gutenberg–Richter formula is calibrated for tectonic earthquakes; explosions or volcanic tremor have different seismic efficiencies.
Frequently asked questions
In ground shaking amplitude, a M7 is 100× stronger than a M5 (10² = 100). In energy released it is about 1,000× greater (10^(1.5×2) ≈ 1,000). This dramatic difference explains why a two-unit magnitude increase represents a vastly more destructive event.
The original Richter scale (ML) was designed for local Southern California earthquakes. Modern moment magnitude (Mw) works globally for all sizes and is now the USGS standard. For M4–7 events the two scales give very similar values.
Yes. The scale has no lower bound — very small tremors are sometimes assigned negative magnitudes. A M−1 quake releases about the energy of a large firecracker and is detectable only by sensitive instruments close to the source.
TG we-Calculate Editorial Team. (2026). Earthquake Calculator — Magnitude, Energy & Comparison [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/earthquake-calculator
TG we-Calculate Editorial Team. "Earthquake Calculator — Magnitude, Energy & Comparison." TG we-Calculate. 2026. https://we-calculate.com/calculator/earthquake-calculator.
TG we-Calculate Editorial Team, "Earthquake Calculator — Magnitude, Energy & Comparison," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/earthquake-calculator
@misc{wecalculate_earthquake_calculator, title = {Earthquake Calculator — Magnitude, Energy & Comparison}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/earthquake-calculator}}, year = {2026}, note = {TG we-Calculate} }
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