Magnitude → energy calculator
Enter a magnitude to see the energy it releases in everyday equivalents. Energy uses the Gutenberg–Richter relation.
Compare two magnitudes
How much stronger is one earthquake than another?
Energy uses log₁₀E = 1.5M + 4.8 (radiated seismic energy, joules); TNT at 4.184×10⁹ J per ton; Hiroshima ≈ 15 kilotons. These are physical energy estimates at the source — felt shaking also depends on depth, distance and ground (see below).
Magnitude classes at a glance
Colours match the dots on the tracker map. Frequencies are rough global averages from USGS.
| Magnitude | Class | What it feels like & typical effects | About how often (world) |
|---|---|---|---|
| < 2.0 | Micro | Not felt by people. Detected only by seismographs. | Millions / year |
| 2.0 – 2.9 | Minor | Rarely felt; recorded by instruments. No damage. | ~1,000,000 / year |
| 3.0 – 3.9 | Minor | Often felt indoors as a brief tremor; hanging objects sway. Very rarely any damage. | ~100,000 / year |
| 4.0 – 4.9 | Light | Noticeable shaking, rattling dishes and windows. Slight damage possible to weak structures. | ~10,000–15,000 / year |
| 5.0 – 5.9 | Moderate | Felt widely; can damage poorly built or older buildings near the epicentre. Well-built structures usually survive. | ~1,000–1,500 / year |
| 6.0 – 6.9 | Strong | Destructive in populated areas up to ~100 km across; serious damage to vulnerable buildings. | ~100–150 / year |
| 7.0 – 7.9 | Major | Serious, widespread damage over large regions; can cause many casualties. | ~10–20 / year |
| 8.0 – 8.9 | Great | Severe destruction across very large areas; can trigger major tsunamis. | ~1 / year |
| 9.0 + | Great | Devastating over vast regions. The largest recorded was M9.5 (Chile, 1960). | ~1 per 10–50 years |
Source: USGS earthquake magnitude classes and frequency estimates. Effects vary a lot with depth, distance and local ground — see the notes below.
Richter vs. moment magnitude (Mw)
Why news reports rarely say "Richter" any more.
Richter scale (ML), 1935
Measures the size of the squiggles a seismograph records. Simple and historic, but it "saturates" for big earthquakes — above about magnitude 7 it stops rising accurately, so a great quake looks smaller than it really is.
Moment magnitude (Mw), today's standard
Based on the physical size of the fault that slipped and the energy released, so it stays accurate at every size. This is what USGS and the tracker report. For moderate quakes Mw and Richter roughly agree, so "magnitude 5.6" means about the same on either.
Each step is a big jump
Magnitude is logarithmic, so the steps are far bigger than they look:
| Difference | Shaking amplitude | Energy released |
|---|---|---|
| +0.1 | ~1.3× larger | ~1.4× more |
| +1.0 | ~10× larger | ~32× more |
| +2.0 | ~100× larger | ~1,000× more |
So a magnitude 7 releases about 32 times the energy of a magnitude 6, and roughly 1,000 times that of a magnitude 5 — even though the numbers look close.
Magnitude isn't the whole story
The single magnitude number describes the earthquake at its source. How strongly you actually feel it — the intensity, measured on the Modified Mercalli scale — also depends on:
- Depth: shallow quakes (less than ~70 km) shake the surface harder than deep ones of the same magnitude.
- Distance: shaking fades quickly with distance from the epicentre.
- Ground type: soft soils and sediment amplify shaking; solid bedrock dampens it.
That's why the tracker shows depth alongside magnitude, and why a shallow M4 next door can feel stronger than a deep M6 far away. Learn more about how seismic waves travel.