Octave & third-octave bands
Exact centre and edge frequencies of octave and third-octave bands, and combining band levels.
Combine three third-octave bands into one octave
dB
dB
dB
Octave band level
75.07dB
Band table
| Nominal | Exact centre | Lower edge | Upper edge |
|---|---|---|---|
| 12.5 Hz | 12.589 Hz | 11.22 Hz | 14.125 Hz |
| 16 Hz | 15.849 Hz | 14.125 Hz | 17.783 Hz |
| 20 Hz | 19.953 Hz | 17.783 Hz | 22.387 Hz |
| 25 Hz | 25.119 Hz | 22.387 Hz | 28.184 Hz |
| 31.5 Hz | 31.623 Hz | 28.184 Hz | 35.481 Hz |
| 40 Hz | 39.811 Hz | 35.481 Hz | 44.668 Hz |
| 50 Hz | 50.119 Hz | 44.668 Hz | 56.234 Hz |
| 63 Hz | 63.096 Hz | 56.234 Hz | 70.795 Hz |
| 80 Hz | 79.433 Hz | 70.795 Hz | 89.125 Hz |
| 100 Hz | 100 Hz | 89.125 Hz | 112.2 Hz |
| 125 Hz | 125.89 Hz | 112.2 Hz | 141.25 Hz |
| 160 Hz | 158.49 Hz | 141.25 Hz | 177.83 Hz |
| 200 Hz | 199.53 Hz | 177.83 Hz | 223.87 Hz |
| 250 Hz | 251.19 Hz | 223.87 Hz | 281.84 Hz |
| 315 Hz | 316.23 Hz | 281.84 Hz | 354.81 Hz |
| 400 Hz | 398.11 Hz | 354.81 Hz | 446.68 Hz |
| 500 Hz | 501.19 Hz | 446.68 Hz | 562.34 Hz |
| 630 Hz | 630.96 Hz | 562.34 Hz | 707.95 Hz |
| 800 Hz | 794.33 Hz | 707.95 Hz | 891.25 Hz |
| 1k Hz | 1000 Hz | 891.25 Hz | 1122 Hz |
| 1.25k Hz | 1258.9 Hz | 1122 Hz | 1412.5 Hz |
| 1.6k Hz | 1584.9 Hz | 1412.5 Hz | 1778.3 Hz |
| 2k Hz | 1995.3 Hz | 1778.3 Hz | 2238.7 Hz |
| 2.5k Hz | 2511.9 Hz | 2238.7 Hz | 2818.4 Hz |
| 3.15k Hz | 3162.3 Hz | 2818.4 Hz | 3548.1 Hz |
| 4k Hz | 3981.1 Hz | 3548.1 Hz | 4466.8 Hz |
| 5k Hz | 5011.9 Hz | 4466.8 Hz | 5623.4 Hz |
| 6.3k Hz | 6309.6 Hz | 5623.4 Hz | 7079.5 Hz |
| 8k Hz | 7943.3 Hz | 7079.5 Hz | 8912.5 Hz |
| 10k Hz | 10000 Hz | 8912.5 Hz | 11220 Hz |
| 12.5k Hz | 12589 Hz | 11220 Hz | 14125 Hz |
| 16k Hz | 15849 Hz | 14125 Hz | 17783 Hz |
| 20k Hz | 19953 Hz | 17783 Hz | 22387 Hz |
Exact frequencies use the base-10 system of IEC 61260 (octave ratio 10^0.3). Band levels add on a power basis.
How it works
Analyzers and acoustic data use standard bands. The nominal labels (such as 31.5 Hz or 12.5 kHz) are rounded; the exact frequencies follow a base-10 series so that ten third-octaves make exactly one decade.
Formulas
- f_m = 1000 Hz · 10^(3x / 10b)
- edges = f_m · 10^(±3 / 20b)
- L_octave = 10 · log₁₀( Σ 10^(L/10) )
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