Earthquake Magnitude Calculator
Calculate moment magnitude Mw from seismic moment or Richter scale.
Returns energy in joules, TNT equivalent in kilotons, and Mercalli intensity description.
Magnitude & Energy
Moment Magnitude (Mw) Mw = (2/3) × log₁₀(Mo) − 10.7, where Mo is the seismic moment in dyne·cm. This is the modern standard scale used by seismologists worldwide.
Richter (Local) Magnitude The original Richter scale (ML) is empirical and works well for small-to-moderate earthquakes. For large earthquakes (ML > 7), moment magnitude is more accurate.
Energy Released log₁₀(E) = 11.8 + 1.5 × Mw (E in ergs). Each whole-number increase in Mw releases about 31.6 times more energy.
TNT Equivalent 1 ton of TNT = 4.184 × 10⁹ J. This converts the released energy into a familiar explosive reference.