Handy Reference Data

Decibel Conversion : Resistor Color Codes : Wire Resistance

Decibel Conversion

dB = 10 log (P/Po) = 20 log (V/Vo), since P = V2 / R

Decibel Percent Voltage Percent Power Comments
0 100% 100%
-0.01 99.9% 99.7%
-0.1 99% 97.7%
-0.2 98% 95.5% Effectively zero.
-0.5 95% 89% Maximum acceptible tolerance for most audio components.
-1 90% 80% Audible
-3 70% 50% Serious
-20 10% 1% The rest included for completeness.
-40 1% 0.01%
-60 0.1% 0.0001%
-80 0.01% 0.000001%
-100 0.001% 0.00000001%

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Resistor Color Codes

Color Significant
Figures		 Multiplier Tolerance
Black 0 1 --
Brown 1 10 ±1%
Red 2 100 ±2%
Orange 3 1,000 ±3%
Yellow 4 10,000 ±4%
Green 5 100,000 --
Blue 6 1,000,000 --
Violet 7 10,000,000 --
Gray 8 100,000,000 --
White 9 -- --
Gold -- 0.1 ±5%
Silver -- 0.01 ±10%
No Color -- -- ±20%

Available Resistance Values

10% tolerance:

10 12 15 18 22 27 33 39 47 56 68 82

5% tolerance:

10 11 12 13 15 16 18 20 22 24 27 30
33 36 39 43 47 51 56 62 68 75 82 91

1% tolerance:

10.0 10.2 10.5 10.7 11.0 11.3 11.5 11.8 12.1 12.4 12.7 13.0
13.3 13.7 14.0 14.3 14.7 15.0 15.4 15.8 16.2 16.5 16.9 17.4
17.8 18.2 18.7 19.1 19.6 20.0 20.5 21.0 21.5 22.1 22.6 23.2
23.7 24.3 24.9 25.5 26.1 26.7 27.4 28.0 28.7 28.4 30.1 30.9
31.6 32.4 33.2 34.0 34.8 35.7 36.5 37.4 38.3 39.2 40.2 41.2
42.2 43.2 44.2 45.3 46.4 47.5 48.7 49.9 51.1 52.3 53.6 54.9
56.2 57.6 59.0 60.4 61.9 63.4 64.9 66.5 68.1 69.8 71.5 73.2
75.0 76.8 78.7 80.6 82.5 84.5 86.6 88.7 90.9 93.1 95.3 97.6

... and multiples thereof.

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Wire Resistance

Wire Size AWG Diameter, mm Area, mm2 Resistance, milliohms/m
10 2.588 5.261 3.277
12 2.05 3.31 5.21
14 1.63 2.08 8.28
16 1.29 1.31 13.2
18 1.02 .823 21.0
20 .813 .519 33.2
22 .643 .324 53.2
24 .511 .205 84.2