How to read SMD resistor codes
SMD resistors of size 0603 and larger usually carry a short code. There are three systems, and you can tell them apart by the number of digits and whether there is a letter at the end. Resistors of size 0402 and smaller usually have no marking, so you have to measure them.
- 3-digit code, usually ±5%: the first two digits are the value and the third is the number of zeros. 103 is 10 followed by three zeros, which is 10 kΩ. 472 is 4.7 kΩ.
- 4-digit code, usually ±1%: the first three digits are the value and the fourth is the number of zeros. 1002 is 100 followed by two zeros, which is 10 kΩ. 4701 is 4.7 kΩ.
- EIA-96 code, ±1%: two digits and a letter, used on small 1% parts. The digits are a position in the E96 series (table below) and the letter is the multiplier. 01C is 100 × 100 = 10 kΩ.
In 3-digit and 4-digit codes the letter R marks the decimal point: 4R7 is 4.7 Ω, R47 is 0.47 Ω and R010 is 0.01 Ω, a typical current sense resistor. A code of 0, 000 or 0000 is a zero-ohm resistor used as a jumper.
EIA-96 multiplier letters
| Letter | Multiplier | Example |
|---|---|---|
| Z | ×0.001 | 01Z = 0.1 Ω |
| Y or R | ×0.01 | 01Y = 1 Ω |
| X or S | ×0.1 | 01X = 10 Ω |
| A | ×1 | 01A = 100 Ω |
| B or H | ×10 | 01B = 1 kΩ |
| C | ×100 | 01C = 10 kΩ |
| D | ×1,000 | 01D = 100 kΩ |
| E | ×10,000 | 01E = 1 MΩ |
| F | ×100,000 | 01F = 10 MΩ |
EIA-96 code table
Find the two digits of the code, take the value next to them and multiply it by the letter. 68X is 499 × 0.1 = 49.9 Ω.
| Code | Value | Code | Value | Code | Value |
|---|---|---|---|---|---|
| 01 | 100 | 33 | 215 | 65 | 464 |
| 02 | 102 | 34 | 221 | 66 | 475 |
| 03 | 105 | 35 | 226 | 67 | 487 |
| 04 | 107 | 36 | 232 | 68 | 499 |
| 05 | 110 | 37 | 237 | 69 | 511 |
| 06 | 113 | 38 | 243 | 70 | 523 |
| 07 | 115 | 39 | 249 | 71 | 536 |
| 08 | 118 | 40 | 255 | 72 | 549 |
| 09 | 121 | 41 | 261 | 73 | 562 |
| 10 | 124 | 42 | 267 | 74 | 576 |
| 11 | 127 | 43 | 274 | 75 | 590 |
| 12 | 130 | 44 | 280 | 76 | 604 |
| 13 | 133 | 45 | 287 | 77 | 619 |
| 14 | 137 | 46 | 294 | 78 | 634 |
| 15 | 140 | 47 | 301 | 79 | 649 |
| 16 | 143 | 48 | 309 | 80 | 665 |
| 17 | 147 | 49 | 316 | 81 | 681 |
| 18 | 150 | 50 | 324 | 82 | 698 |
| 19 | 154 | 51 | 332 | 83 | 715 |
| 20 | 158 | 52 | 340 | 84 | 732 |
| 21 | 162 | 53 | 348 | 85 | 750 |
| 22 | 165 | 54 | 357 | 86 | 768 |
| 23 | 169 | 55 | 365 | 87 | 787 |
| 24 | 174 | 56 | 374 | 88 | 806 |
| 25 | 178 | 57 | 383 | 89 | 825 |
| 26 | 182 | 58 | 392 | 90 | 845 |
| 27 | 187 | 59 | 402 | 91 | 866 |
| 28 | 191 | 60 | 412 | 92 | 887 |
| 29 | 196 | 61 | 422 | 93 | 909 |
| 30 | 200 | 62 | 432 | 94 | 931 |
| 31 | 205 | 63 | 442 | 95 | 953 |
| 32 | 210 | 64 | 453 | 96 | 976 |
Frequently asked questions
What is a 103 SMD resistor?
103 is 10 × 10³ = 10 kΩ, usually with ±5% tolerance. The same value is marked 1002 on a 1% resistor and 01C in EIA-96.
Is 4R7 4.7 Ω or 4.7 kΩ?
4.7 Ω. On SMD resistors R always stands for the decimal point in ohms. Codes don’t use K or M; 4.7 kΩ is written 472 or 4701.
How do I tell a 3-digit code from an EIA-96 code?
An EIA-96 code always ends in a letter (01C, 68X). A 3-digit code is all digits, or has an R in the middle (4R7). If a code like 10R ends in R, it’s EIA-96 by the standard (1.24 Ω), but some makers use it for 10 Ω, so compare it with the other resistors on the board.