Earthquake magnitude comparison
Enter both magnitudes to see the real difference; one step means ten times the recorded shaking amplitude.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter first magnitude and second magnitude.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Amplitude ratio = 10^(M₂ − M₁) and energy ratio = 10^(1.5 × (M₂ − M₁)). Ratios are shown for the stronger quake over the weaker.
Example
Inputs: First magnitude = 5, Second magnitude = 7. Result: Energy released is greater by: 1,000 times; Shaking amplitude is greater by: 100 times; Result: The second quake (7) is stronger than the first (5).
Limits and caveats
- Real damage also depends on depth, distance, soil and buildings, not magnitude alone.
- Ratios are approximate and follow the standard logarithmic magnitude relations.
Questions about this tool
Is a magnitude 8 twice as strong as a 4?
No. It releases about a million times more energy, because the scale is logarithmic.
What is the difference between amplitude and energy ratios?
Amplitude is the size of the shaking on a seismograph; energy is what the quake actually releases, and it grows faster.
Can I enter decimals like 6.4?
Yes, enter magnitudes with one decimal as monitoring agencies publish them.