Learn to read SMD resistor codes fast. Decode 3-digit, 4-digit and EIA-96 markings with tables, worked examples, standards and a detailed FAQ.

INTRODUCTION

Surface-mount resistors are so small that colour bands cannot be printed on them. Instead, manufacturers print a short code of numbers, or numbers and a letter, on the top of the part. Once you know the rules, you can read any of these codes in a few seconds.

This guide teaches you to decode the three marking systems found on SMD chip resistors:

The 3-digit code, used for standard 5% resistors (E24 series)
The 4-digit code, used for precision 1% resistors (E96 series)
The EIA-96 code, a compact 2-digit + 1-letter code used for 1% resistors on very small packages

You will also learn the R notation for low values, how to spot zero-ohm jumpers, which package sizes carry markings, which international standards define the codes, and how to verify a value with a multimeter.

Who this guide is for: electronics students, hobbyists, PCB assembly and rework technicians, hardware and repair engineers, and purchasing or stores staff who verify incoming components.

SMD Resistor Code: Decode 3-Digit, 4-Digit and EIA-96 Markings

Chip resistors are too small for colour bands, so they carry a short printed code. Learn the three marking systems and read any SMD resistor in seconds.

472

3-digit
4.7 kΩ

4702

4-digit
47 kΩ

01C

EIA-96
10 kΩ

Beginner to intermediate15 to 20 minute readIncludes lookup tables and a live decoder

What you will learn

Why SMD resistors use printed codes instead of colour bands
How to decode 3-digit, 4-digit and EIA-96 codes
How to read R notation (4R7, R47, 10R0) and spot zero-ohm jumpers
Which package sizes carry which markings
Which standards define the codes, and how to verify a value with a multimeter

This guide suits students, hobbyists, PCB assembly and rework technicians, repair engineers, and stores staff who check incoming parts.

What is an SMD resistor?

An SMD (Surface Mount Device) resistor, or chip resistor, is a small rectangular part soldered straight onto the PCB surface. It has no leads, only metal end terminations. A typical chip has a ceramic (alumina) substrate, a thick-film or thin-film resistive layer, a dark protective overcoat that carries the marking, and tin-plated end terminations.

A 0603 chip measures about 1.6 mm x 0.8 mm and can sit with either face up, so colour bands are impractical. A code printed on top, read with a magnifier, solves this.

The three codes at a glance

3-digit

472

2 digits + multiplier. Typically 5% (E24 series). Reads 4.7 kΩ.

4-digit

4702

3 digits + multiplier. Typically 1% (E96 series). Reads 47 kΩ.

EIA-96

01C

2-digit index + letter. Typically 1% on small packages. Reads 10 kΩ.

The one idea behind all three: significant digits first, multiplier last. Only the way the multiplier is written changes.

Try the decoder

Type a marking (for example 472, 1002, 68C, 4R7 or 000)

The 3-digit code

Value (Ω) = (Digit 1 Digit 2) x 10^{Digit 3}

The third digit is the multiplier: it tells you how many zeros to add after the first two digits. For example, 473 is 47 followed by three zeros, which is 47,000 Ω or 47 kΩ.

Third digit	Multiplier	Zeros added
0	x 1	none
1	x 10	1
2	x 100	2
3	x 1,000	3
4	x 10,000	4
5	x 100,000	5
6	x 1,000,000	6

Digits 8 and 9 are rarely used as multipliers (x 0.01 and x 0.1). If you see one, check the datasheet.

Marking	Working	Value
`100`	10 x 1	10 Ω
`221`	22 x 10	220 Ω
`471`	47 x 10	470 Ω
`102`	10 x 100	1 kΩ
`222`	22 x 100	2.2 kΩ
`103`	10 x 1,000	10 kΩ
`104`	10 x 10,000	100 kΩ
`334`	33 x 10,000	330 kΩ
`105`	10 x 100,000	1 MΩ
`475`	47 x 100,000	4.7 MΩ

The 4-digit code

Precision resistors (1%, 0.5%, 0.1%) use E96 and E192 values such as 49.9 or 69.8. These need three significant figures, so a fourth digit carries the multiplier.

Value (Ω) = (Digits 1 2 3) x 10^{Digit 4}

Marking	Working	Value
`1000`	100 x 1	100 Ω
`1001`	100 x 10	1 kΩ
`1002`	100 x 100	10 kΩ
`1003`	100 x 1,000	100 kΩ
`4991`	499 x 10	4.99 kΩ
`4992`	499 x 100	49.9 kΩ
`6980`	698 x 1	698 Ω
`1004`	100 x 10,000	1 MΩ

Common mistake: 1001 is not 1,001 Ω. It is 100 followed by one zero: 1 kΩ. The last digit is always the multiplier.

Same value, different codes

Value	3-digit (5%)	4-digit (1%)
100 Ω	101	1000
1 kΩ	102	1001
10 kΩ	103	1002
100 kΩ	104	1003
1 MΩ	105	1004

R notation and zero-ohm resistors

The letter R stands for the decimal point. It is not a multiplier.

Marking	Value
`4R7`	4.7 Ω
`R47`	0.47 Ω
`10R0`	10.0 Ω
`49R9`	49.9 Ω
`R010`	0.010 Ω (10 mΩ, a current-sense value)

A zero-ohm resistor is a jumper link marked 0, 000 or 0000. It is not a perfect conductor: expect under about 50 mΩ and a current limit (often 1 to 2 A for 0603 and 0805). Never use it as a fuse.

The EIA-96 code

Tiny precision resistors (mostly 0603, some 0805) have no room for four characters. EIA-96 packs the value into two digits and one letter. The two digits are an index from 01 to 96 into the E96 table, and the letter is the multiplier.

Value (Ω) = Table(index) x Multiplier(letter)

Multiplier letters

Letter	Z	Y / R	X / S	A	B / H	C	D	E	F
Multiplier	0.001	0.01	0.1	1	10	100	1,000	10,000	100,000

Index lookup table (index and three-figure value)

Worked examples

Marking	Table value	Multiplier	Result
`01A`	100	x 1	100 Ω
`01C`	100	x 100	10 kΩ
`68C`	499	x 100	49.9 kΩ
`49B`	316	x 10	3.16 kΩ
`85D`	750	x 1,000	750 kΩ
`33X`	215	x 0.1	21.5 Ω
`96E`	976	x 10,000	9.76 MΩ

Spot the difference: 01C (10 kΩ, EIA-96) and 011 (110 Ω, 3-digit) look alike. A trailing letter means EIA-96. EIA-96 letters are not tolerance letters.

Package sizes and which marking appears where

Imperial	Metric	Size (mm)	Typical power	Usual marking
0201	0603M	0.6 x 0.3	1/20 W	none
0402	1005M	1.0 x 0.5	1/16 W	usually none
0603	1608M	1.6 x 0.8	1/10 W	3-digit or EIA-96
0805	2012M	2.0 x 1.25	1/8 W	3-digit, 4-digit or EIA-96
1206	3216M	3.2 x 1.6	1/4 W	3-digit or 4-digit
1210	3225M	3.2 x 2.5	1/2 W	3-digit or 4-digit
2010	5025M	5.0 x 2.5	3/4 W	3-digit or 4-digit
2512	6332M	6.3 x 3.2	1 W	3-digit or 4-digit

Power ratings are typical and vary by manufacturer, so check the datasheet. Marking style also hints at tolerance: 3-digit is usually 5%, while 4-digit and EIA-96 are usually 1%. This is a trend, not a rule. Parts of 0402 and smaller are normally unmarked; identify them from the reel label, the BOM or by measurement.

Standards behind the codes

Standard	Covers
EIA-96	Marking code for E96 surface-mount resistors (2 digits + letter)
IEC 60062	Marking codes for resistors and capacitors: digit codes, R notation, tolerance letters
IEC 60063	Preferred number series E3 to E192
IEC 60115-8	Fixed surface-mount (chip) resistors
IPC-7351	Surface mount land pattern design
IPC-A-610	Acceptability of electronic assemblies
J-STD-001	Soldered electrical and electronic assemblies

Series	E12	E24	E48	E96	E192
Values per decade	12	24	48	96	192
Typical tolerance	10%	5%	2%	1%	0.5% and tighter

Tolerance letters (IEC 60062), seen in part numbers: B 0.1%, C 0.25%, D 0.5%, F 1%, G 2%, J 5%, K 10%, M 20%. Standards are revised over time, so confirm the current edition with IEC, IPC or ECIA before citing it.

Decode any marking in four questions

1. Is there an R in the middle? R is the decimal point. 4R7 = 4.7 Ω.

2. Two digits and a letter? EIA-96. Look up the index, apply the letter. 68C = 499 x 100 = 49.9 kΩ.

3. Three or four digits? 3 digits: 2 figures + multiplier (472 = 4.7 kΩ). 4 digits: 3 figures + multiplier (4702 = 47 kΩ).

4. All zeros? Zero-ohm jumper. Otherwise check the datasheet or measure.

Sanity check: if the result is not a standard E24 or E96 value, you have probably misread it.

Cheat sheet

3-digit: AB C = AB x 10^C
4-digit: ABC D = ABC x 10^D
EIA-96: NN L = Table(NN) x Multiplier(L)
R code: xRy = x.y Ω | Zero-ohm: 0 / 000 / 0000

Confirm by measurement

Power off the board and discharge capacitors.
Ideally lift one end of the resistor, since in-circuit readings are often low.
Press the probes firmly on both end terminations.
Expect a 5% part within 5% and a 1% part within 1%, allowing for meter accuracy.
Below 1 Ω, use a four-wire (Kelvin) measurement.
Use a magnifier, side lighting and clean off flux so the characters are readable.

Practice

Decode these, then open the answers.

3-digit
221 473 684 330

4-digit
1003 2201 4992 5110

EIA-96
01C 22B 65D 96C

R notation
2R2 R22 15R0 R050

Show answers

3-digit: 221 = 220 Ω; 473 = 47 kΩ; 684 = 680 kΩ; 330 = 33 Ω (not 330 Ω).
4-digit: 1003 = 100 kΩ; 2201 = 2.2 kΩ; 4992 = 49.9 kΩ; 5110 = 511 Ω.
EIA-96: 01C = 10 kΩ; 22B = 1.65 kΩ; 65D = 464 kΩ; 96C = 97.6 kΩ.
R notation: 2R2 = 2.2 Ω; R22 = 0.22 Ω; 15R0 = 15 Ω; R050 = 50 mΩ.
Write the code: 330 Ω = 331; 56 kΩ = 563; 2.2 kΩ = 2201; 4.99 kΩ = 68B; 100 kΩ = 01D.

Frequently asked questions

What does the third digit in a 3-digit code mean?

It is the multiplier, the number of zeros to add after the first two digits. 472 is 47 plus two zeros: 4,700 Ω or 4.7 kΩ.

How do I read a 4-digit code?

The first three digits are the value and the fourth is the multiplier. 1002 is 100 plus two zeros: 10 kΩ.

What is EIA-96 and when is it used?

A three-character code (two digits and a letter) for 1% E96 resistors, mainly on small packages like 0603. The digits are an index into a 96-value table and the letter is the multiplier.

How do I tell EIA-96 from a 3-digit code?

Look at the last character. A letter means EIA-96; all digits means a 3-digit or 4-digit code. 01C is 10 kΩ, while 011 is 110 Ω.

What does R mean in 4R7?

R is the decimal point: 4R7 is 4.7 Ω, R47 is 0.47 Ω and 10R0 is 10.0 Ω.

What does 000 or 0 mean?

A zero-ohm jumper. It has a very small resistance (typically under 50 mΩ) and a current limit, so it is not a perfect conductor.

Why is my SMD resistor not marked?

Packages of 0402 and smaller are usually too small to print on, and some thin-film precision parts are left blank. Use the reel label, the BOM, or measure it.

Is 103 the same as 1003?

No. 103 is 10 kΩ and 1003 is 100 kΩ. Count the digits before decoding.

Does the code show the tolerance?

Not directly. 3-digit usually means 5% and 4-digit or EIA-96 usually means 1%, but the datasheet is the real authority.

Can I rely on a multimeter to check the value?

Yes for most values, if the part is out of circuit or isolated from parallel paths. Milliohm values need a four-wire measurement.

Why do 1% resistors use a different code from 5% ones?

E96 values such as 49.9 or 69.8 need three significant figures. A 3-digit code only holds two plus a multiplier, so 4-digit or EIA-96 is used.

Can I replace a 1% resistor with a 5% one?

Only if the circuit tolerates it. Reference dividers, ADC inputs, feedback networks and filters usually need the tighter tolerance.

How are current-sense resistors marked?

Usually in R notation, for example R010 for 10 mΩ. Many use a Kelvin (four-terminal) footprint, so follow the datasheet.

Are the codes the same worldwide?

The digit codes and R notation come from IEC 60062 and EIA-96 is widely used, but some manufacturers use variants. When in doubt, read the datasheet.

Where can I find official tables?

In manufacturer marking guides and datasheets (Vishay, Yageo, Panasonic, KOA, Bourns) and in IEC 60062, IEC 60063 and the EIA-96 specification.

Key takeaways

Every SMD code is significant digits plus a multiplier.
3-digit: 2 figures + multiplier (about 5%). 4-digit: 3 figures + multiplier (about 1%). EIA-96: index + letter (about 1%).
R is a decimal point; 0, 000 and 0000 are jumpers.
0402 and smaller are usually unmarked.
Sanity-check against E24 or E96 and measure when unsure.

SMD Resistor Code: How to Decode 3-Digit, 4-Digit and EIA-96 Markings