g to SI Acceleration Conversion
Converting acceleration expressed in multiples of g to SI units (m/s^2) and to imperial units (in/s^2), with the standard gravitational acceleration values.
Conversion factors
Acceleration in seismic engineering is commonly expressed as a fraction or multiple of the acceleration due to gravity (g). To convert to SI units, multiply by the standard gravitational acceleration. In SI: 1g = 9.80665 m/s^2 (commonly rounded to 9.81 m/s^2). In imperial units: 1g = 386.09 in/s^2 (commonly rounded to 386 in/s^2).
Common conversions
| Acceleration (g) | SI (m/s^2) | Imperial (in/s^2) | Context |
|---|---|---|---|
| 0.05 | 0.491 | 19.3 | Low seismic hazard |
| 0.10 | 0.981 | 38.6 | Moderate seismic hazard |
| 0.20 | 1.961 | 77.2 | Moderate spectral amplification |
| 0.30 | 2.942 | 115.8 | High spectral amplification |
| 0.50 | 4.903 | 193.0 | High seismic demand |
| 0.75 | 7.355 | 289.6 | Severe seismic demand |
| 1.00 | 9.807 | 386.1 | 1g reference |
| 2.00 | 19.613 | 772.2 | Floor amplification peak |
Notes
- Always confirm the g value used by the solver — some solvers use 9.81, others 9.80665
- Response spectra are often tabulated in g; the solver must convert to the model unit system
- Zero-period acceleration (ZPA) is typically expressed in g and represents the peak ground acceleration