The dB is used to compare two values (numerator vs. denominator) in a logarithmic scale. It may be used as a relative (both values are variable) or absolute (one value is set as a reference) metric.
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For Power Quantities (such as Watts or Watts/m2 )
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For Non-Power Quantities (such as Pa, V, inches/sec, G)
or
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|
Quantity |
Formula |
Reference |
| Voltage (dBV) | Non Power | 1 VRMS |
| dBm | Power | 1 mWatt |
| dBu | Non Power | 0.775 VRMS |
| Sound Pressure | Non Power | 20 μPa |
| Sound Intensity | Power | 1 pWatt/m2 |
| Sound Power | Power | 1 pWatt |
| Acceleration | Non Power | 1 µm/s2 * |
| Velocity | Non Power | 1 nm/s * |
| *Non-standard references often used especially in USA and machine vibration | ||
| dB | Non Power Ratio |
Power Ratio |
|
dB | Non Power Ratio |
Power Ratio |
| 0.0 | 1.000 | 1.000 | 6 | 1.995 | 3.981 | |
| 0.1 | 1.012 | 1.023 | 7 | 2.239 | 5.012 | |
| 0.2 | 1.023 | 1.047 | 8 | 2.512 | 6.310 | |
| 0.3 | 1.035 | 1.072 | 9 | 2.818 | 7.943 | |
| 0.4 | 1.047 | 1.096 | 10 | 3.162 | 10.000 | |
| 0.5 | 1.059 | 1.122 | 12 | 3.981 | 15.849 | |
| 0.6 | 1.072 | 1.148 | 14 | 5.012 | 25.119 | |
| 0.7 | 1.084 | 1.175 | 16 | 6.310 | 39.811 | |
| 0.8 | 1.096 | 1.202 | 18 | 7.943 | 63.096 | |
| 0.9 | 1.109 | 1.230 | 20 | 10.000 | 1.0E+02 | |
| 1.0 | 1.122 | 1.259 | 30 | 31.623 | 1.0E+03 | |
| 1.5 | 1.189 | 1.413 | 40 | 100.000 | 1.0E+04 | |
| 2.0 | 1.259 | 1.585 | 50 | 316.228 | 1.0E+05 | |
| 3.0 | 1.413 | 1.995 | 60 | 1.0E+03 | 1.0E+06 | |
| 4.0 | 1.585 | 2.512 | 70 | 3.2E+03 | 1.0E+07 | |
| 5.0 | 1.778 | 3.162 | 80 | 1.0E+04 | 1.0E+08 |
