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The Electronic
Industries Association (EIA), and other authorities, specify standard
values for resistors, sometimes referred to as the "preferred value"
system. The preferred value system has its origins in the early years of
the last century at a time when most resistors were carbon-graphite with
relatively poor manufacturing tolerances. The rationale is simple - select
values for components based on the tolerances with which they are able to
be manufactured. Using 10% tolerance devices as an example, suppose that
the first preferred value is 100 ohms. It makes little sense to produce a
105 ohm resistor since 105 ohms falls within the 10% tolerance range of
the 100 ohm resistor. The next reasonable value is 120 ohms because the
100 ohm resistor with a 10% tolerance is expected to have a value
somewhere between 900 and 110 ohms. The 120 ohm resistor has a value
ranging between 110 and 130 ohms. Following this logic, the preferred
values for 10% tolerance resistors between 100 and 1,000 ohms would be
100, 120, 150, 180, 220, 270, 330 and so on (rounded appropriately); this
is the E12 series shown in the table below.
The EIA "E" series specify the preferred values for various
tolerances. The number following the "E" specifies the number of
logarithmic steps per decade. The table below is normalized for the decade
between 100 and 1,000. The values in any decade can be derived by merely
dividing or multiplying the table entries by powers of 10. The series are
as follows:
E6 20% tolerance,
E12 10% tolerance,
E24 5% tolerance (and usually 2% tolerance),
E48 2% tolerance,
E96 1% tolerance,
E192 .5, .25, .1% and higher tolerances.
Standard EIA Decade Values Table (100 to 1,000 Decade)
E6 |
E12 |
E24 |
E48 |
E96 |
E192 |
100 |
100 |
100 |
100 |
100 |
100 |
101 |
102 |
102 |
104 |
105 |
105 |
105 |
106 |
107 |
107 |
109 |
110 |
110 |
110 |
110 |
111 |
113 |
113 |
114 |
115 |
115 |
115 |
117 |
118 |
118 |
120 |
120 |
120 |
121 |
121 |
121 |
123 |
124 |
124 |
126 |
127 |
127 |
127 |
129 |
130 |
130 |
132 |
130 |
133 |
133 |
133 |
135 |
137 |
137 |
138 |
140 |
140 |
140 |
142 |
143 |
143 |
145 |
150 |
150 |
150 |
147 |
147 |
147 |
149 |
150 |
150 |
152 |
154 |
154 |
154 |
156 |
158 |
158 |
160 |
160 |
162 |
162 |
162 |
164 |
165 |
165 |
167 |
169 |
169 |
169 |
172 |
174 |
174 |
176 |
180 |
180 |
178 |
178 |
178 |
180 |
182 |
182 |
184 |
187 |
187 |
187 |
189 |
191 |
191 |
193 |
200 |
196 |
196 |
196 |
198 |
200 |
200 |
203 |
205 |
205 |
205 |
208 |
210 |
210 |
213 |
|
E6 |
E12 |
E24 |
E48 |
E96 |
E192 |
220 |
220 |
220 |
215 |
215 |
215 |
218 |
221 |
221 |
223 |
226 |
226 |
226 |
229 |
232 |
232 |
234 |
240 |
237 |
237 |
237 |
240 |
243 |
243 |
246 |
249 |
249 |
249 |
252 |
255 |
255 |
258 |
270 |
270 |
261 |
261 |
261 |
264 |
267 |
267 |
271 |
274 |
274 |
274 |
277 |
280 |
280 |
284 |
300 |
287 |
287 |
287 |
291 |
294 |
294 |
298 |
301 |
301 |
301 |
305 |
309 |
309 |
312 |
330 |
330 |
330 |
316 |
316 |
316 |
320 |
324 |
324 |
328 |
332 |
332 |
332 |
336 |
340 |
340 |
344 |
360 |
348 |
348 |
348 |
352 |
357 |
357 |
361 |
365 |
365 |
365 |
370 |
374 |
374 |
379 |
390 |
390 |
383 |
383 |
383 |
388 |
392 |
392 |
397 |
402 |
402 |
402 |
407 |
412 |
412 |
417 |
430 |
422 |
422 |
422 |
427 |
432 |
432 |
437 |
442 |
442 |
442 |
448 |
453 |
453 |
459 |
|
E6 |
E12 |
E24 |
E48 |
E96 |
E192 |
470 |
470 |
470 |
464 |
464 |
464 |
470 |
475 |
475 |
481 |
487 |
487 |
487 |
493 |
499 |
499 |
505 |
510 |
511 |
511 |
511 |
517 |
523 |
523 |
530 |
536 |
536 |
536 |
542 |
549 |
549 |
556 |
560 |
560 |
562 |
562 |
562 |
569 |
576 |
576 |
583 |
590 |
590 |
590 |
597 |
604 |
604 |
612 |
620 |
619 |
619 |
619 |
626 |
634 |
634 |
642 |
649 |
649 |
649 |
657 |
665 |
665 |
673 |
680 |
680 |
680 |
681 |
681 |
681 |
690 |
698 |
698 |
706 |
715 |
715 |
715 |
723 |
732 |
732 |
741 |
750 |
750 |
750 |
750 |
759 |
768 |
768 |
777 |
787 |
787 |
787 |
796 |
806 |
806 |
816 |
820 |
820 |
825 |
825 |
825 |
835 |
845 |
845 |
856 |
866 |
866 |
866 |
876 |
887 |
887 |
898 |
910 |
909 |
909 |
909 |
920 |
931 |
931 |
942 |
953 |
953 |
953 |
965 |
976 |
976 |
988 |
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