| dBu | Ratio | Voltage | dBu | Ratio | Voltage | |
| 0 | 1.00 | 0.7746 | 0 | 1.000 | 0.7746 | |
| 1 | 1.12 | 0.8691 | -1 | 0.891 | 0.6904 | |
| 2 | 1.26 | 0.9752 | -2 | 0.794 | 0.6153 | |
| 3 | 1.41 | 1.0941 | -3 | 0.708 | 0.5484 | |
| 4 | 1.58 | 1.2277 | -4 | 0.631 | 0.4887 | |
| 5 | 1.78 | 1.3774 | -5 | 0.562 | 0.4356 | |
| 6 | 2.00 | 1.5455 | -6 | 0.500 | 0.3882 | |
| 7 | 2.24 | 1.7341 | -7 | 0.447 | 0.3460 | |
| 8 | 2.51 | 1.9457 | -8 | 0.398 | 0.3084 | |
| 9 | 2.82 | 2.1831 | -9 | 0.355 | 0.2748 | |
| 10 | 3.16 | 2.4495 | -10 | 0.316 | 0.2449 | |
| 11 | 3.55 | 2.7484 | -11 | 0.282 | 0.2183 | |
| 12 | 3.98 | 3.0837 | -12 | 0.251 | 0.1946 | |
| 13 | 4.47 | 3.4600 | -13 | 0.224 | 0.1734 | |
| 14 | 5.01 | 3.8822 | -14 | 0.200 | 0.1546 | |
| 15 | 5.62 | 4.3559 | -15 | 0.178 | 0.1377 | |
| 16 | 6.31 | 4.8874 | -16 | 0.159 | 0.1228 | |
| 17 | 7.08 | 5.4837 | -17 | 0.141 | 0.1094 | |
| 18 | 7.94 | 6.1528 | -18 | 0.126 | 0.0975 | |
| 19 | 8.91 | 6.9036 | -19 | 0.112 | 0.0869 | |
| 20 | 10.00 | 7.7460 | -20 | 0.100 | 0.0775 | |
| 21 | 11.22 | 8.6911 | -21 | 0.089 | 0.0690 | |
| 22 | 12.59 | 9.7516 | -22 | 0.079 | 0.0615 | |
| 23 | 14.13 | 10.9415 | -23 | 0.071 | 0.0548 | |
| 24 | 15.85 | 12.2765 | -24 | 0.063 | 0.0489 | |
| 25 | 17.78 | 13.7745 | -25 | 0.056 | 0.0436 | |
| 26 | 19.95 | 15.4552 | -26 | 0.050 | 0.0388 | |
| 27 | 22.39 | 17.3411 | -27 | 0.045 | 0.0346 | |
| 28 | 25.12 | 19.4570 | -28 | 0.040 | 0.0308 | |
| 29 | 28.18 | 21.8311 | -29 | 0.036 | 0.0275 | |
| 30 | 31.62 | 24.4949 | -30 | 0.032 | 0.0245 | |
| 31 | 35.48 | 27.4837 | -31 | 0.028 | 0.0218 | |
| 32 | 39.81 | 30.8372 | -32 | 0.025 | 0.0195 | |
| 33 | 44.67 | 34.6000 | -33 | 0.022 | 0.0173 | |
| 34 | 50.12 | 38.8218 | -34 | 0.020 | 0.0155 | |
| 35 | 56.23 | 43.5588 | -35 | 0.018 | 0.0138 | |
| 36 | 63.10 | 48.8737 | -36 | 0.016 | 0.0123 | |
| 37 | 70.79 | 54.8372 | -37 | 0.014 | 0.0109 | |
| 38 | 79.43 | 61.5284 | -38 | 0.013 | 0.0098 | |
| 39 | 89.12 | 69.0360 | -39 | 0.011 | 0.0087 | |
| 40 | 100.00 | 77.4597 | -40 | 0.010 | 0.0077 |
The table shows the ratio and voltage equivlent to a given level in dBu from +40 dBu to -40 dBu
dBu is a logrithmic voltage notation relative to 0.7746 Volts but not related to any impedance.
dBm (the traditional unit 50 years ago) is relative to 1 mW into 600 ohms and is numerically equal to dBu.
dBV (rarely used) is relative to 1.0 Volts and like dBu, is not related to any impedance.
Comments and questions to support@sowter.co.uk
OTHER USEFUL INFORMATION
To convert max level at 50 Hz to 20 Hz subtract 7.96 dB
To convert an rms voltage to a peak voltage multiply by 1.414
To convert an rms voltage to a p-p voltage multiply by 2.828
To convert a dB value to a ratio in Excel: Ratio =POWER(10,dB/20)
To convert a ratio to a dB value in Excel: dB =20*LOG(ratio)