How to Read SMD Resistor Codes — 103 · 4R7 · 01C markings and chip resistor part numbers explained

Picture: A customer looks through a magnifier at a chip resistor on a circuit board. The chip is marked 103. The customer asks, “If it says 103, is it 103 ohms?” and the staff member raises a finger and answers, “No, it’s 10 kilohms.”

Characters such as 103, 4R7 and 01C printed on chip resistors (SMD resistors) are abbreviated resistance values. It is easy to read "103" as 103Ω, but it is actually 10kΩ. Learn a few rules and you can read the value with nothing but a magnifier.

1. 3-digit · 4-digit numbers

The last digit is "how many zeros to add". Add that many zeros after the preceding digits to get the value in Ω (ohms).

• 3 digits (±5% standard) — first two digits + number of zeros. 103 = 10 followed by three zeros = 10,000Ω = 10kΩ, 472 = 4.7kΩ, 221 = 220Ω
• 4 digits (±1% precision, size 0805 and larger) — first three digits + number of zeros. 1002 = 100 followed by two zeros = 10.0kΩ, 4701 = 4.70kΩ
• 0 · 000 — not a resistor but a 0Ω jumper (used to connect traces)

Picture: A customer points to a note on the desk that reads 100 and asks in surprise, “It says 100, but it’s 10 ohms?” The staff member makes a V and a circle with her fingers and explains, “There are no zeros after the 10, so it’s 10 ohms!”

The most common mistake: 100 = 10Ω. The last digit 0 means "add no zeros", so it stays 10, i.e. 10Ω. For the same reason, 4-digit 1000 = 100Ω and 3-digit 470 = 47Ω.

2. Markings with R (small resistors)

Small values below 10Ω use R as the decimal point. 4R7 = 4.7Ω, 2R2 = 2.2Ω, R47 = 0.47Ω. The same applies to 4 digits: 31R6 = 31.6Ω. Very small current-sense resistors are sometimes written as R010 = 0.01Ω (10mΩ) or 1m5 = 1.5mΩ.

3. EIA-96 codes (2 digits + a letter, like 01C · 88A)

Precision (±1%) resistors in size 0603 have no room for 4 digits, so they are abbreviated to 2 digits + 1 letter (EIA-96). The digits are a value index (01 = 100 … 96 = 976, table above), and the letter is the multiplier.

Letters: Y·S ×0.01 · X·R ×0.1 · A ×1 · B·H ×10 · C ×100 · D ×1,000 · E ×10,000. An 0603 resistor with an underline beneath a 3-digit number indicates a ±1% type (e.g. E24 values such as 10Ω · 11Ω).

4. Sizes and unmarked resistors

Sizes 0402 and smaller are too small to be marked. In that case, measure with a multimeter or check the value from the part number on the reel label. Rated power varies by series (high-power types, etc.) even at the same size, so check the datasheet.

5. Reading chip resistor part numbers on reel labels

The part number on a reel label contains the size, tolerance, value and packaging. Here we break down part numbers from Yageo, the world's most widely used brand, and Korea's Samsung Electro-Mechanics as examples.

Yageo RC0603FR-0710KL — RC (general purpose) · 0603 (size) · F (±1%) · R (paper tape reel) · - (temperature coefficient per spec) · 07 (7-inch reel) · 10K (10kΩ) · L (fixed ordering letter). In the value field, R · K · M are decimal points: 4K7 = 4.7kΩ, 97R6 = 97.6Ω, 1M = 1MΩ. The same value at ±5% is RC0603JR-0710KL.

Samsung Electro-Mechanics RC1608J103CS — RC (general purpose) · 1608 (size, mm) · J (±5%) · 103 (10kΩ, same scheme as the body marking) · CS (packaging). For ±1%, the value has 4 digits: RC1608F1273CS = 127kΩ.

※ Size notation differs by company — Yageo uses inches (0603), Samsung Electro-Mechanics uses mm (1608). They are the same size. More size traps are covered in How to Read MLCC Part Numbers.

Sources: Yageo Chip Resistor Marking specification · Yageo RC_L series datasheet (November 2025) · TT Electronics TN004 (EIA-96 code table) · Samsung Electro-Mechanics chip resistor part numbers. Marking schemes may vary slightly by manufacturer and series, so confirm exact values with a multimeter or the datasheet.