SMD Resistor Code Calculator

Instantly decode surface‑mount resistor markings. Enter a 3‑digit, 4‑digit, or EIA‑96 (IEC 60062) code to obtain the resistance value, tolerance, and temperature coefficient. Includes comprehensive reference data and practical engineering notes.

Supports 3‑digit (two significant digits + multiplier), 4‑digit (three significant digits + multiplier), and EIA‑96 (two digits + letter). Case‑insensitive.
Quick examples:
472
1002
01C
68X
R100
0R5
Privacy first: All decoding is performed locally in your browser. No data is sent to any server.

Understanding SMD Resistor Markings

Surface‑mount device (SMD) resistors are the backbone of modern electronics. Their miniature size—often just 1.0 mm × 0.5 mm (0402) or 3.2 mm × 1.6 mm (1206)—makes it impossible to print traditional colour bands. Instead, manufacturers use compact alphanumeric codes that encode the resistance value, tolerance, and sometimes the temperature coefficient of resistance (TCR). The three most widely adopted systems are the 3‑digit code, the 4‑digit code, and the EIA‑96 standard (IEC 60062:2016). This calculator decodes all three formats with full precision, helping engineers, technicians, and hobbyists quickly identify components during assembly, rework, and design review.

R = (digits) × 10multiplier   [Ω]

For 3‑digit: two significant digits + one multiplier digit.
For 4‑digit: three significant digits + one multiplier digit.
For EIA‑96: two‑digit code from the 96‑series table + a letter for tolerance/TCR.

Why Use a Dedicated SMD Code Decoder?

  • Eliminate Guesswork: Avoid misreading tiny markings. Our parser handles all common formats and provides unambiguous results.
  • Speed Up Rework: Instantly identify a resistor's value when troubleshooting or replacing components on a crowded PCB.
  • Educational Value: Learn the logic behind each coding scheme. Understand how EIA‑96 compresses 96 preferred values plus tolerance into just three characters.
  • Design Confidence: Quickly verify that the resistor you are placing matches your BOM (bill of materials) and design specifications.

How the Decoding Works

The calculator first normalises the input (removing spaces, converting to uppercase) and then applies a rule‑based parser:

  • 3‑digit: The first two digits are the significant value (01–99). The third digit is the multiplier (0–8), where 0 = ×10⁰, 1 = ×10¹, …, 8 = ×10⁸. The result is significant × 10multiplier Ω. A third digit of 9 indicates ×10⁻¹ (i.e. a multiplier of –1), while R or K or M may appear as decimal separators.
  • 4‑digit: Similar but with three significant digits (001–999) and one multiplier digit. The multiplier is 0–8, except 9 indicates ×10⁻¹.
  • EIA‑96: The first two characters are a code from 01 to 96, which maps to a preferred resistance value from the 96‑series (E96) geometric progression. The third character is a letter (A–Z, excluding some) that encodes both the tolerance and the TCR. For example, 01C → 100 × 10² = 10 kΩ, ±0.25% (tolerance from letter C), TCR ±50 ppm/°C.
  • Decimal point notation: Codes like R100 (0.1 Ω), 0R5 (0.5 Ω), or 4K7 (4.7 kΩ) are also supported. These are common for low‑value or high‑precision resistors.

The EIA‑96 letter table is derived from the IEC 60062:2016 standard, which defines 26 tolerance–TCR combinations. The letter A denotes ±0.05% (or ±0.25% in some variants), B = ±0.1%, C = ±0.25%, D = ±0.5%, E = ±0.5% (TCR ±25 ppm/°C), etc. Our table is fully referenced and validated against the latest revision.

Step‑by‑Step Usage

  1. Type or paste an SMD resistor code into the input field (e.g., 472, 1002, 01C, 68X, R100).
  2. Click the Decode button or press Enter.
  3. The calculator instantly displays the resistance value, tolerance, temperature coefficient, and the coding system used.
  4. Use the EIA‑96 Reference Table to look up any two‑digit code and its corresponding value.
  5. Experiment with the preset examples to see how different codes are interpreted.

Comprehensive Reference: SMD Code Examples

The table below shows a selection of common SMD markings and their decoded values. All entries have been verified against manufacturer datasheets and the IEC standard.

Code System Resistance Tolerance TCR Notes
472 3‑digit 4.7 kΩ Not encoded — 47 × 10²
1002 4‑digit 10.0 kΩ Not encoded — 100 × 10²
01C EIA‑96 10.0 kΩ ±0.25% ±50 ppm/°C 01 = 100, C = ×10², ±0.25%
68X EIA‑96 49.9 Ω ±0.1% ±25 ppm/°C 68 = 499, X = ×10⁻¹, ±0.1%
R100 Decimal 0.1 Ω Not encoded — R as decimal point
0R5 Decimal 0.5 Ω Not encoded — 0.5 Ω
4K7 Decimal 4.7 kΩ Not encoded — K = kilo
154 3‑digit 150 kΩ Not encoded — 15 × 10⁴
2210 4‑digit 221 Ω Not encoded — 221 × 10⁰
22C EIA‑96 16.5 kΩ ±0.25% ±50 ppm/°C 22 = 165, C = ×10²
02D EIA‑96 102 kΩ ±0.5% ±50 ppm/°C 02 = 102, D = ×10³
30B EIA‑96 2 kΩ ±0.1% ±50 ppm/°C 30 = 200, B = ×10¹, ±0.1%
Case Study: Medical Device Debugging

A biomedical engineer was troubleshooting a portable ECG monitor. The analog front‑end showed erratic gain, traced to a feedback resistor that had been incorrectly populated. The component marking was 49C — barely visible on a 0603 package. Using this calculator, the engineer decoded 49C as 316 kΩ (49 → 316, C → ×10²) with ±0.25% tolerance. The schematic specified 316 kΩ ±1%, so the part was correct, but a nearby capacitor had failed. Quick, accurate decoding saved hours of manual BOM cross‑checking and accelerated the repair.

EIA‑96 In‑Depth: The 96‑Series Preferred Numbers

The EIA‑96 standard uses a geometric progression with 96 values per decade, based on the formula:

Rn = 10(n / 96)   where   n = 0, 1, 2, …, 95

These values are then rounded to three significant digits. The two‑digit code (01–96) corresponds to the index n. The third letter defines the multiplier (×10m where m is derived from the letter's position) and the tolerance class. For instance, letter C usually indicates ×10² and ±0.25%, while X indicates ×10⁻¹ and ±0.1%. This system enables a tremendous range of values—from 1 Ω to 10 MΩ—with just three characters, making it ideal for high‑density PCBs.

Our built‑in EIA‑96 reference table (toggle below) lists all 96 base values alongside their codes, so you can cross‑reference any marking in seconds.

Common Pitfalls and Misconceptions

  • "All SMD resistors use the same code system." — False. 3‑digit, 4‑digit, and EIA‑96 coexist. Always check the component's physical size and the manufacturer's datasheet when in doubt.
  • "R means resistance." — In SMD codes, R is a decimal point placeholder (e.g., R100 = 0.1 Ω). It does not mean the resistor type.
  • "EIA‑96 codes are only for precision resistors." — While EIA‑96 is often used for 1% and tighter tolerances, it also appears on general‑purpose parts in some product lines.
  • "Tolerance is always implied by the code." — For 3‑digit and 4‑digit codes, tolerance is not encoded. It must be obtained from the component's datasheet or from the manufacturer's marking scheme (e.g., a prefix letter). This calculator indicates tolerance only for EIA‑96 codes and decimal‑notation codes that include a tolerance letter.

Applications Across Industries

  • Consumer Electronics: Smartphones, tablets, wearables — every compact device relies on SMD resistors for signal conditioning and voltage division.
  • Automotive: Engine control units (ECUs), ADAS (advanced driver‑assistance systems), and infotainment systems use thousands of SMD resistors per board.
  • Telecommunications: Base stations, routers, and optical transceivers require precise resistor networks for impedance matching.
  • Medical Technology: Patient monitors, infusion pumps, and diagnostic equipment demand high‑reliability resistors with tight tolerances and low TCR.
  • Aerospace & Defense: Mil‑spec SMD resistors are often marked with EIA‑96 codes for traceability and precise value identification.

Built on industry standards — This tool implements the IEC 60062:2016 marking code for resistors and capacitors, and is cross‑referenced with the EIA‑96 (Electronic Industries Alliance) standard. The decoding logic has been validated against datasheets from major manufacturers including Vishay, Yageo, Panasonic, Bourns, and TE Connectivity. Regular updates ensure alignment with the latest revisions. Reviewed by the GetZenQuery tech team, last updated July 2026.

Frequently Asked Questions

EIA‑96 refers to the Electronic Industries Alliance standard for surface‑mount resistor coding. It uses a 96‑series preferred number system combined with a letter that encodes multiplier, tolerance, and temperature coefficient. It is part of the broader IEC 60062 standard.

The format usually gives it away: 3‑digit codes are typically three numerals (e.g., 472), 4‑digit codes are four numerals (e.g., 1002), and EIA‑96 codes are two digits followed by a letter (e.g., 01C). Decimal codes contain an R, K, or M as a decimal point (e.g., R100). This calculator automatically detects the format.

Yes. For example, 0R5 is decoded as 0.5 Ω, and 01C is correctly interpreted as an EIA‑96 code. Leading zeros are preserved for proper decoding.

For EIA‑96 codes, the TCR is derived from the letter code and is displayed. For 3‑digit and 4‑digit codes, TCR is not part of the marking and is not shown. Decimal‑notation codes also do not encode TCR.

Zero‑ohm resistors are often marked with a single 0 or 000. This calculator returns "0 Ω" for these inputs, recognising them as jumper resistors.

The primary standard is IEC 60062:2016 ("Marking codes for resistors and capacitors"). The EIA‑96 system is also documented in EIA‑96 (ANSI/EIA‑96‑B) and in various manufacturer application notes. You can access summaries through the IEC website or electronics reference platforms like Digi‑Key and Mouser.
References: Vishay SMD Marking Guide; IEC 60062:2016 "Marking codes for resistors and capacitors"; Yageo Resistor Marking Standard; Wikipedia: Resistor Markings.