How to Read SMD Resistor Codes
In a 3-digit SMD resistor code the first two digits are significant figures, the third is the multiplier, and the result is in ohms: 472 = 47 × 10² = 4,700 Ω = 4.7 kΩ. The letter 'R' is the decimal point (4R7 = 4.7 Ω). Precision resistors use a 4-digit code or EIA-96 (2 digits + a letter).
Quick reminder: on a 3-digit SMD resistor code the value = (first two digits) × 10(third digit) ohms; 472 = 4.7 kΩ, and "R" is the decimal point (4R7 = 4.7 Ω). Our SMD Resistor Code Calculator does that instantly. This article focuses on the genuinely confusing parts: EIA-96, unmarked resistors and special markings.
Why does EIA-96 exist, and how do you decode it?
A 1% resistor's value needs 3 significant figures (e.g. 4.99 kΩ), but three digits + a multiplier don't fit on a small body. The solution is EIA-96: two digits encode a value (from the E96 table) and a letter gives the multiplier → 3 significant figures in 3 characters.
The two digits are NOT the value directly — they are a table code (E96 values):
| Code | Value | Code | Value |
|---|---|---|---|
| 01 | 100 | 40 | 255 |
| 10 | 124 | 68 | 499 |
| 20 | 158 | 70 | 523 |
| 25 | 178 | 96 | 976 |
(The full table has 96 entries = the E96 values.) The letter multipliers:
| Letter | Multiplier |
|---|---|
| Y / R | ×0.01 |
| X / S | ×0.1 |
| A | ×1 |
| B / H | ×10 |
| C | ×100 |
| D | ×1,000 |
| E | ×10,000 |
| F | ×100,000 |
Examples: 01A = 100 × 1 = 100 Ω · 25B = 178 × 10 = 1.78 kΩ · 68C = 499 × 100 = 49.9 kΩ.
Zero ohms (000) — the jumper resistor
000 (or 0000 / 0R00) is a zero-ohm resistor, used on the board as a bridge/jumper: to cross a track on a single-layer layout, an optional link, a current-sense point, or a stand-in for a manual wire in automated assembly. Even at zero ohms it has a maximum current rating.
Unmarked SMD resistors
Very small bodies (0402, 0201 and most 0603) are too small to print a code on → they are unmarked. Find the value like this:
- The board's BOM / silkscreen reference (e.g. R12) → the value from the schematic.
- Hard to measure in place; remove it and measure with a multimeter.
The underline / bar marking
Some codes have a line underneath. This shows the reading orientation — to avoid confusing symmetric codes (e.g. to tell 618 from 819). Some makers also print precision codes in bold/underlined.
How it differs from a capacitor code
An SMD resistor code resolves directly to ohms; a capacitor's 3-digit code gives picofarads. Resistors use R for the decimal (4R7 = 4.7 Ω); capacitors default to pF. So the same "472" means 4.7 kΩ on a resistor but 4,700 pF (4.7 nF) on a capacitor.
Use the calculator
To enter a 3/4-digit or EIA-96 code and get the value instantly, use our SMD Resistor Code Calculator.