SMD Resistor Code Calculator

3-digit, 4-digit, and EIA-96 markings

Operating Mode

Required Parameters

Marking

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Quick Answer

SMD resistor codes decode as: 3-digit (e.g., 472 = 4700Ω), 4-digit (e.g., 4702 = 47kΩ), or EIA-96 (e.g., 01A = 100Ω). The last digit/letter is always the multiplier. R indicates decimal point (4R7 = 4.7Ω).

Documentation

SMD Resistor Code Calculator — Engineering Reference

Use this calculator to decode 3-digit, 4-digit, and EIA-96 marking codes on surface-mount (SMD) resistors into their actual resistance values. SMD resistors use compact alphanumeric codes instead of color bands.

3-Digit Code System

The most common marking system. The first two digits are significant figures, and the third digit is the multiplier (number of zeros to add).

Code	Meaning	Value
103	10 × 10³	10 kΩ
472	47 × 10²	4.7 kΩ
220	22 × 10⁰	22 Ω
4R7	4.7 (R = decimal)	4.7 Ω
R47	0.47	0.47 Ω

The "R" Convention: The letter "R" replaces the decimal point. So "4R7" means 4.7 Ω, and "R10" means 0.10 Ω.

4-Digit Code System

Used for precision resistors (1% tolerance or better). First three digits are significant, the fourth is the multiplier.

Code	Meaning	Value
1001	100 × 10¹	1 kΩ
4702	470 × 10²	47 kΩ
1000	100 × 10⁰	100 Ω
10R0	10.0	10 Ω

EIA-96 Code System

Used for precision 1% resistors. Combines a two-digit number (01–96) with a letter multiplier:

Letter	Multiplier
Z	×0.001
Y or R	×0.01
X or S	×0.1
A	×1
B or H	×10
C	×100
D	×1000
E	×10000
F	×100000

The two-digit number maps to a value in the E96 resistor series. For example:

01C = 100 × 100 = 10 kΩ
68B = 499 × 10 = 4.99 kΩ

Reading Tips

Orientation — On many SMD resistors, the code reads left-to-right with the component oriented so the marking is not upside down.
No marking — Zero-ohm jumper resistors typically have just "0" or "000" printed.
Very small packages — 0201 and 0402 packages often have no marking at all due to size.
Confusion with capacitors — SMD capacitors are usually unmarked. If a component looks identical but has no marking, it may be a capacitor.

Standard SMD Package Sizes

Package	Dimensions (mm)	Dimensions (inches)	Power Rating
0201	0.6 × 0.3	0.02 × 0.01	1/20W
0402	1.0 × 0.5	0.04 × 0.02	1/16W
0603	1.6 × 0.8	0.06 × 0.03	1/10W
0805	2.0 × 1.25	0.08 × 0.05	1/8W
1206	3.2 × 1.6	0.12 × 0.06	1/4W
2512	6.3 × 3.2	0.25 × 0.12	1W

Related Tools

Resistor Color Code Calculator — Decode through-hole resistor band colors
SMD Capacitor Code Calculator — Decode capacitor markings
Ohm's Law Calculator — Apply decoded values in circuit calculations
Resistor Calculator — Combine decoded resistors in series or parallel

Design Notes

SMD resistor markings vary by manufacturer and package size. Packages 0402 and smaller often use EIA-96 because there is only room for 3 characters. Larger packages (0603+) typically use 3 or 4-digit codes. Zero-ohm resistors (marked 000 or 0) serve as SMD jumper wires for routing.

Common Mistakes

1
Confusing SMD resistor codes with capacitor codes — both use 3-digit numeric systems but in different units (ohms vs picofarads).
2
Forgetting that the R position indicates the decimal point, not the letter R as a multiplier.
3
Reading EIA-96 codes with the wrong lookup table — some manufacturers use non-standard letter assignments.

Engineering Handbox

1. First two digits: 47 (significant figures) 2. Third digit: 2 (add two zeros) 3. Result: 47 + 00 = 4700Ω

VerificationThe SMD marking 472 decodes to 4,700 ohms (4.7 kΩ).

Knowledge Base

What is EIA-96?

EIA-96 is a 3-character marking system for 1% tolerance SMD resistors. The first two characters are a number (01-96) referencing a lookup table of base values, and the third character is a letter indicating the multiplier. Example: 01A = 100Ω, 68C = 49.9kΩ. It fits on tiny 0402/0201 packages where 4-digit codes are too small to print.

How do I read a 3-digit SMD resistor code?

The first two digits are the significant figures and the third digit is the number of zeros (multiplier). Example: 472 = 47 + 00 = 4,700Ω (4.7kΩ). 103 = 10 + 000 = 10,000Ω (10kΩ). 330 = 33 + no zeros = 33Ω. Exception: R is used for decimal point, so 4R7 = 4.7Ω.

How do I read a 4-digit SMD resistor code?

Same as 3-digit but with three significant figures for higher precision (1% tolerance). The last digit is the multiplier. Example: 4702 = 470 + 00 = 47,000Ω (47kΩ). 1001 = 100 + 0 = 1,000Ω (1kΩ). 10R0 = 10.0Ω.

What does R mean in SMD resistor codes?

R indicates the decimal point position. 4R7 = 4.7Ω, R47 = 0.47Ω, 1R0 = 1.0Ω. This notation is used for low-value resistors below 10Ω where the standard multiplier system cannot represent the value.

What does 000 or 0 mean on an SMD component?

A marking of 000 (3-digit) or 0000 (4-digit) indicates a zero-ohm resistor, which is effectively a jumper wire in SMD form. These are used to connect traces on a PCB where routing on a single layer is impossible, and they can be placed by the same pick-and-place machine as other SMD components.

Why are some SMD resistors not marked at all?

Very small packages (0201 and 01005) are often unmarked because there is no room for printing. Also, some manufacturers omit markings on 0402 and larger sizes to reduce cost. If you encounter unmarked SMD resistors, measure them with a multimeter or check the BOM against the PCB placement file.

What is the difference between E24 and E96 resistor series?

E24 has 24 standard values per decade (5% tolerance): 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91. E96 has 96 values per decade (1% tolerance), providing much finer granularity. E96 values include 100, 102, 105, 107, 110... through 976.

How do I identify the EIA-96 multiplier letter?

The letter follows the two-digit base code: Z=0.001, Y/R=0.01, X/S=0.1, A=1, B/H=10, C=100, D=1000, E=10000, F=100000. Example: 33B = base value 215Ω (from table position 33) × 10 = 2.15kΩ. Note: some manufacturers use alternative letters, so always verify with the datasheet.

Can SMD resistor codes be confused with capacitor codes?

Yes, this is a common problem. Both use similar 3-digit numeric codes, but capacitor codes are in picofarads while resistor codes are in ohms. The safest way to distinguish them: check the BOM, check the schematic, or look at the package color (resistors are typically black/dark, while some ceramic capacitors are tan/brown/grey).

What are common SMD resistor values I should memorize?

The most commonly used values: 0Ω (jumper), 10Ω, 100Ω, 1kΩ (102), 4.7kΩ (472), 10kΩ (103), 47kΩ (473), 100kΩ (104), 1MΩ (105). Pull-up/pull-down standards: 4.7kΩ for I2C, 10kΩ for GPIO, 1kΩ for LED current limiting at 3.3V.

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