The Electronic Industries Association (EIA), and then statued by IEC publication 60063, specify standard values for resistors, sometimes referred to as the "preferred value" system. The 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. A value of 105 ohm resistor falls within the 10% tolerance range of the 100 ohm resistor, so the next value outside the range is 120. A 120 ohm resistor has a value ranging between 110 and 130 ohms and the next value might be 150 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, ... (see table below). This gives the E12 series which contains 12 elements. The EIA "E" series specify the preferred values for various tolerances. The number following the "E" specifies the number of logarithmic steps per decade, or the values in the series. The tables below are 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: - E3 50% tolerance (no longer used) - E6 20% tolerance (now seldom used) -E12 10% tolerance -E24 5% tolerance (and usually 2% tolerance) -E48 2% tolerance (also for inventory cost control in place of E96) -E96 1% tolerance -E192 0.5%, 0.25%, 0.1% and higher tolerances. A formula to approximate a value for a member in a class is: V(n) = Round(100*exp((n-1)/N*ln(10))) where V(n) is value for the n-th member in class E-N (i.e. N=192,96,48,24,12,6,3). E-3 (50%) 100 220 470 E-6 (20%) 100 150 220 330 470 680 E-12 (10%) 100 150 220 330 470 680 120 180 270 390 560 820 E-24 (2% and 5%) 100 150 220 330 470 680 110 160 240 360 510 750 120 180 270 390 560 820 130 200 300 430 620 910 E-48 (2%) 100 133 174 226 301 402 536 715 105 140 178 237 316 422 562 750 110 147 187 249 332 442 590 787 115 154 196 261 348 464 619 825 121 162 205 274 365 487 649 866 127 169 215 287 383 511 681 909 E-96 (1%) 100 147 215 316 464 681 102 150 221 324 475 698 105 154 226 332 487 715 107 158 232 340 499 732 110 162 237 348 511 750 113 165 243 357 523 768 115 169 249 365 536 787 118 174 255 374 549 806 121 178 261 383 562 825 124 182 267 392 576 845 127 187 274 402 590 866 130 191 280 412 604 887 133 196 287 422 619 909 137 200 294 432 634 931 140 205 301 442 649 953 143 210 309 453 665 976 E-192 (0.1%, 0.25% and 0.5%) 100 121 147 178 215 261 316 383 464 562 681 825 101 123 149 180 218 264 320 388 470 569 690 835 102 124 150 182 221 267 324 392 475 576 698 845 104 126 152 184 223 271 328 397 481 583 706 856 105 127 154 187 226 274 332 402 487 590 715 866 106 129 156 189 229 277 336 407 493 597 723 876 107 130 158 191 232 280 340 412 499 604 732 887 109 132 160 193 234 284 344 417 505 612 741 898 110 133 162 196 237 287 348 422 511 619 750 909 111 135 164 198 240 291 352 427 517 626 759 920 113 137 165 200 243 294 357 432 523 634 768 931 114 138 167 203 246 298 361 437 530 642 777 942 115 140 169 205 249 301 365 442 536 649 787 953 117 142 172 208 252 305 370 448 542 657 796 965 118 143 174 210 255 309 374 453 549 665 806 976 120 145 176 213 258 312 379 459 556 673 816 988

 
 
US MICROWAVES
Advanced Microwave Components		 Standard EIA Decade Values
 
 

The Electronic Industries Association (EIA), and then statued by IEC publication 60063, specify standard values for resistors, sometimes referred to as the "preferred value" system.
The 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. A value of 105 ohm resistor falls within the 10% tolerance range of the 100 ohm resistor, so the next value outside the range is 120. A 120 ohm resistor has a value ranging between 110 and 130 ohms and the next value might be 150 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, ... (see table below). This gives the E12 series which contains 12 elements.
The EIA "E" series specify the preferred values for various tolerances. The number following the "E" specifies the number of logarithmic steps per decade, or the values in the series. The tables below are 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:

- E3 50% tolerance (no longer used)
- E6 20% tolerance (now seldom used)
-E12 10% tolerance
-E24 5% tolerance (and usually 2% tolerance)
-E48 2% tolerance (also for inventory cost control in place of E96)
-E96 1% tolerance
-E192 0.5%, 0.25%, 0.1% and higher tolerances.

A formula to approximate a value for a member in a class is:
V(n) = Round(100*exp((n-1)/N*ln(10)))
where V(n) is value for the n-th member in class E-N
(i.e. N=192,96,48,24,12,6,3).

E-3 (50%)
100 220 470

E-6 (20%)
100 150 220 330 470 680

E-12 (10%)
100 150 220 330 470 680
120 180 270 390 560 820

E-24 (2% and 5%)
100 150 220 330 470 680
110 160 240 360 510 750
120 180 270 390 560 820
130 200 300 430 620 910
E-48 (2%)
100 133 174 226 301 402 536 715
105 140 178 237 316 422 562 750
110 147 187 249 332 442 590 787
115 154 196 261 348 464 619 825
121 162 205 274 365 487 649 866
127 169 215 287 383 511 681 909

E-96 (1%)
100 147 215 316 464 681
102 150 221 324 475 698
105 154 226 332 487 715
107 158 232 340 499 732
110 162 237 348 511 750
113 165 243 357 523 768
115 169 249 365 536 787
118 174 255 374 549 806
121 178 261 383 562 825
124 182 267 392 576 845
127 187 274 402 590 866
130 191 280 412 604 887
133 196 287 422 619 909
137 200 294 432 634 931
140 205 301 442 649 953
143 210 309 453 665 976

E-192 (0.1%, 0.25% and 0.5%)
100 121 147 178 215 261 316 383 464 562 681 825
101 123 149 180 218 264 320 388 470 569 690 835
102 124 150 182 221 267 324 392 475 576 698 845
104 126 152 184 223 271 328 397 481 583 706 856
105 127 154 187 226 274 332 402 487 590 715 866
106 129 156 189 229 277 336 407 493 597 723 876
107 130 158 191 232 280 340 412 499 604 732 887
109 132 160 193 234 284 344 417 505 612 741 898
110 133 162 196 237 287 348 422 511 619 750 909
111 135 164 198 240 291 352 427 517 626 759 920
113 137 165 200 243 294 357 432 523 634 768 931
114 138 167 203 246 298 361 437 530 642 777 942
115 140 169 205 249 301 365 442 536 649 787 953
117 142 172 208 252 305 370 448 542 657 796 965
118 143 174 210 255 309 374 453 549 665 806 976
120 145 176 213 258 312 379 459 556 673 816 988

Last updated: July 01, 2009
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