Reference chart

SMD resistor code chart

Surface-mount (SMD) resistors are too small for colour bands, so they carry a printed code of three or four characters. There are three systems, and you can tell which one you have by counting digits and looking for a letter.

Which code is it?

Marking	System	Usual tolerance	Example
3 digits	3-digit code	±5%	472 = 4.7 kΩ
4 digits	4-digit code	±1%	4702 = 47 kΩ
2 digits and a letter	EIA-96 code	±1%	01C = 10 kΩ
An R among digits	R is the decimal point	either	4R7 = 4.7 Ω

The smallest parts (0402 and below) usually have no marking at all, so keep them in their labelled tape.

3-digit codes

The first two digits are the value and the third is how many zeros follow, in ohms:

472 = 47 and 2 zeros = 4,700 Ω = 4.7 kΩ

Code	Value	Code	Value
100	10 Ω	103	10 kΩ
220	22 Ω	223	22 kΩ
101	100 Ω	473	47 kΩ
221	220 Ω	104	100 kΩ
331	330 Ω	474	470 kΩ
102	1 kΩ	105	1 MΩ
472	4.7 kΩ	000	0 Ω link

4-digit codes

Precision ±1% parts use three digits for the value and the fourth for the zeros:

4702 = 470 and 2 zeros = 47,000 Ω = 47 kΩ

Code	Value	Code	Value
1000	100 Ω	1002	10 kΩ
2200	220 Ω	4702	47 kΩ
1001	1 kΩ	1003	100 kΩ
4991	4.99 kΩ	1004	1 MΩ

R for the decimal point

Values under 10 Ω (or 100 Ω in the 4-digit code) can't be written with zeros, so an R marks the decimal point:

4R7 = 4.7 Ω
R47 = 0.47 Ω
10R0 = 10 Ω
R100 = 0.1 Ω

EIA-96 codes

The tiniest ±1% resistors only have room for three characters. Two digits pick one of the 96 values of the E96 series, and a letter multiplies it:

01C = 100 × 100 = 10 kΩ

Codes 01–24	Codes 25–48	Codes 49–72	Codes 73–96
01 = 100	25 = 178	49 = 316	73 = 562
02 = 102	26 = 182	50 = 324	74 = 576
03 = 105	27 = 187	51 = 332	75 = 590
04 = 107	28 = 191	52 = 340	76 = 604
05 = 110	29 = 196	53 = 348	77 = 619
06 = 113	30 = 200	54 = 357	78 = 634
07 = 115	31 = 205	55 = 365	79 = 649
08 = 118	32 = 210	56 = 374	80 = 665
09 = 121	33 = 215	57 = 383	81 = 681
10 = 124	34 = 221	58 = 392	82 = 698
11 = 127	35 = 226	59 = 402	83 = 715
12 = 130	36 = 232	60 = 412	84 = 732
13 = 133	37 = 237	61 = 422	85 = 750
14 = 137	38 = 243	62 = 432	86 = 768
15 = 140	39 = 249	63 = 442	87 = 787
16 = 143	40 = 255	64 = 453	88 = 806
17 = 147	41 = 261	65 = 464	89 = 825
18 = 150	42 = 267	66 = 475	90 = 845
19 = 154	43 = 274	67 = 487	91 = 866
20 = 158	44 = 280	68 = 499	92 = 887
21 = 162	45 = 287	69 = 511	93 = 909
22 = 165	46 = 294	70 = 523	94 = 931
23 = 169	47 = 301	71 = 536	95 = 953
24 = 174	48 = 309	72 = 549	96 = 976

EIA-96 multiplier letters

Letter	Multiply by	Example
Z	× 0.001	01Z = 0.1 Ω
Y or R	× 0.01	01Y = 1 Ω
X or S	× 0.1	68X = 49.9 Ω
A	× 1	85A = 750 Ω
B or H	× 10	01B = 1 kΩ
C	× 100	01C = 10 kΩ
D	× 1,000	30D = 200 kΩ
E	× 10,000	01E = 1 MΩ
F	× 100,000	01F = 10 MΩ

Reading one, step by step

Count the characters and look for a letter. That tells you the system.
A letter at the end of two digits: look up the digits in the EIA-96 table, then multiply by the letter.
An R among digits: put a decimal point where the R is.
Only digits: everything but the last digit is the value, and the last digit is how many zeros to add.

Free lesson

Now build it yourself

Each lesson comes in three short parts: see the idea, try it on a live board, then build it yourself, with quick checks as you go.

Try it yourself: free lesson

“Resistance: the squeeze” is lesson 4 of 6 in Copper Flats, Electronics World 1. Free with an account. Lessons unlock in order, so you’ll do the 3 before it first.

Or start from the very first lesson, no account needed

Work it out

Resistor colour code calculatorBands to ohms, or ohms to bands, on 4- and 5-band resistors.

The ideas behind it

What is resistance?The squeeze on the flow, in ohms: how resistors set the current and protect an LED.

Questions people ask

What does 103 mean on an SMD resistor?

10 followed by three zeros: 10,000 Ω, which is 10 kΩ. The first two digits are the value and the last is how many zeros come after them.

What does R mean in a resistor code?

R is the decimal point, and it's how values under 10 Ω are written. 4R7 is 4.7 Ω, 10R0 is 10 Ω and R100 is 0.1 Ω. A resistor marked 0 or 000 is a 0 Ω link, used as a jumper.

How do I read a resistor code like 01C?

Two digits and a letter is an EIA-96 code, used on ±1% resistors. The digits pick a value from the EIA-96 table (01 is 100) and the letter is the multiplier (C is × 100), so 01C is 10 kΩ.

Is 100 on an SMD resistor 100 Ω?

No: on a 3-digit resistor, 100 means 10 and no zeros, so 10 Ω. A 100 Ω part is marked 101, or 1000 in the 4-digit code. Check how many digits there are before you read it.