Table of approximate worst-case (highest) ESR values for new electrolytic capacitors at 20 degrees C (68'F). ESR generally decreases with increasing temperature.

       10V      16V     25V     35V     63V    100V    250V
     _______________________________________________________
    |       |       |       |       |       |       |       |
1uF |   xxx |   xxx |   xxx |  < 14 |  < 16 |  < 18 |  < 20 |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
2.2uF  xxx  | xxx   | 6.0   | 8.0   | < 10  | < 10  | < 18  |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
4.7uF  xxx  | xxx   | 15    | 7.5   | 4.2   | 2.3   | 5.0   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
10uF   xxx  | 8.0   | 5.3   | 3.2   | 2.4   | 3.0   | 2.5   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
22uF   5.4  | 3.6   | 2.1   | 1.5   | 1.5   | 1.5   | 1.8   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
47uF   2.2  | 1.6   | 1.2   | 0.68  | 0.56  | 0.7   | 0.8   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
100uF  1.2  | 0.7   | 0.32  | 0.32  | 0.3   | 0.15  | 0.8   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
220uF  0.6  | 0.33  | 0.23  | 0.17  | 0.16  | 0.09  | 0.5   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
470uF  0.24 | 0.18  | 0.12  | 0.09  | 0.09  | 0.05  | 0.3   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
1,000uF 0.12| 0.09  | 0.08  | 0.07  | 0.05  | 0.06  | xxx   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
4,700uF 0.23| 0.20  | 0.12  | 0.08  | 0.04  | xxx   | xxx   |
    |_______|_______|_______|_______|_______|_______|_______|
    |       |       |       |       |       |       |       |
10,000uF 0.12 0.08  | 0.06  | 0.04  | xxx   | xxx   | xxx   |
    |_______|_______|_______|_______|_______|_______|_______|

Notes: These figures are a guide only! Some electrolytics (especially high temperature types) can give higher readings and still be OK. Others can read significantly lower and be OK. In general, be wary of a capacitor with an ESR reading more than double the figures shown here. If you get a reading less than half, check the capacitor with an ohm meter... it might be shorted.

Written November '98, by Bob Parker.

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