SMD Resistor Code Calculator
Decode SMD resistor markings like 103, 4702, 4R7, R010 and EIA-96 01C into ohms, or turn a resistance into its 3-digit, 4-digit and EIA-96 code.
The interactive tool loads here when JavaScript runs.
About this toolWhat is the SMD Resistor Code Calculator?
Surface-mount resistors are too small for colour bands, so they carry a short printed code instead. There are three systems in common use: a 3-digit code for ordinary 5% parts, a 4-digit code for 1% parts, and the EIA-96 code of two digits and a letter that fits on 0603 and smaller 1% parts. The letter R marks a decimal point in values below 10 or 100 Ω. This SMD resistor code calculator reads all of them and shows the working, so 103 becomes 10 × 10³ = 10 kΩ and 01C becomes 100 × 100 = 10 kΩ.
It also works the other way. Type a resistance with its unit and the calculator gives the 3-digit, 4-digit and EIA-96 codes, says whether each one is exact or the nearest code available, and shows the alternative EIA-96 letters (R, S, H) some makers print. A filterable E96 table lets you look up any EIA-96 code by its index or value.
- Decodes 3-digit, 4-digit, R notation and EIA-96 codes
- Encodes any value into all three families, flagging nearest codes
- Shows the arithmetic and the tolerance each family implies
- E24 and E96 membership check
- Searchable EIA-96 table with alternative letters R, S and H
- Works offline in the browser, shareable link
How to use the SMD Resistor Code Calculator
- Type the code exactly as printed, for example 103, 4702, 4R7, R047 or 01C. Case does not matter.
- Read the resistance, the code family and the tolerance that family usually implies.
- Check the E-series note: a 3-digit value should be an E24 value, a 4-digit or EIA-96 value an E96 value.
- To go the other way, enter a value and unit in Resistance to code and read the three codes.
- Use the EIA-96 table to look up a code index or to find which index a value has.
Worked examples
3-digit code
Input
103
Output
10 kΩ
10 × 10³. A ±5% chip resistor in the E24 range.
4-digit code
Input
4702
Output
47 kΩ
470 × 10². The extra digit means the part is 1% or better.
R as the decimal point
Input
4R7 and R010
Output
4.7 Ω and 0.01 Ω (10 mΩ)
R010 is a typical shunt for current sensing; check its power rating and temperature coefficient in the datasheet.
EIA-96
Input
68X
Output
49.9 Ω
Index 68 in the E96 table is 499, and X multiplies by 0.1.
Value to code
Input
12.1 kΩ
Output
3-digit 123 (nearest, 12 kΩ, −0.83%), 4-digit 1212, EIA-96 09C
12.1 kΩ is an E96 value, so it has exact 4-digit and EIA-96 codes but no exact 3-digit code.
Background and insight
The 3-digit code follows the same rule as resistor colour bands and ceramic capacitors: two significant figures and a power-of-ten multiplier. 472 is 47 × 10² = 4.7 kΩ. Because only two figures fit, the code matches the E24 series of IEC 60063, and parts marked this way are normally ±5%. The 4-digit code adds a third significant figure, 4701 being 470 × 10¹ = 4.7 kΩ, which covers the E96 and E192 values used for 1% and better. Below 10 Ω (3-digit) or 100 Ω (4-digit), R takes the place of the decimal point: 4R7 is 4.7 Ω and R010 is 0.010 Ω, a common current-sense value.
On 0603 and 0402 parts there is not room for four characters, so the EIA-96 marking system, named after the E96 series it encodes, packs a 1% value into three. The two digits, 01 to 96, are the position of the value in the E96 series, so 01 is 100, 02 is 102 and 96 is 976. The letter is a multiplier: Z ×0.001, Y or R ×0.01, X or S ×0.1, A ×1, B or H ×10, C ×100, D ×1,000, E ×10,000 and F ×100,000. So 68X is the 68th E96 value, 499, times 0.1: 49.9 Ω. The same table appears in the marking guides of many chip-resistor makers.
Many 0402 and smaller parts carry no marking at all. In that case, and when a code is worn or ambiguous, measure the part out of circuit with a meter. A code like 47R can mean two different things: under EIA-96 it is 301 × 0.01 = 3.01 Ω, but some older parts used a trailing R to mean ohms. The calculator reads it as EIA-96 and warns you.
Common use cases
Board repair
Identify a burnt or suspect chip resistor from its neighbours or a reference board.
Prototyping and rework
Check that the reel you picked up is the value the BOM calls for before hand-placing parts.
Reverse engineering
Read the values on an unknown board to rebuild a schematic.
Ordering spares
Turn a value into the codes you will see on parts from different makers.
Tips and limitations
- A 3-digit code does not prove 5%: some 1% parts in E24 values still use it. Check the reel label or datasheet when tolerance matters.
- Codes on tiny parts are easy to misread upside down: 601 and 109 look alike. A third digit of 8 or 9 is not used on resistors, which helps spot the mistake.
- Measure in circuit with care: parallel paths make the reading low. Lift one end for an accurate value.
- Zero-ohm links (000 or 0) are jumpers with a current rating, often 1 A or more for an 0603 part.
- Some makers use their own marking on precision or automotive parts. When a code fits none of these systems, look up the maker's marking guide.
Frequently asked questions
What does 103 mean on an SMD resistor?
It is 10 followed by three zeros: 10,000 Ω or 10 kΩ. The first two digits are the value and the third is the number of zeros (the power of ten).
What does R mean in a resistor code?
R marks the decimal point. 4R7 is 4.7 Ω, 47R0 is 47.0 Ω and R047 is 0.047 Ω.
How do I read an EIA-96 code like 01C?
Look up the two digits in the E96 table (01 = 100) and multiply by the letter (C = ×100). 01C is 100 × 100 = 10 kΩ.
What is the difference between 3-digit and 4-digit SMD codes?
A 3-digit code has two significant figures and fits E24 values, usually ±5% parts. A 4-digit code has three significant figures and fits E96 or E192 values, used for ±1% and better.
What resistor is marked 000?
A zero-ohm jumper. It joins two pads and is used for options or to cross a trace on single-layer boards.
Why does my SMD resistor have no marking?
0402 and smaller resistors are usually left unmarked because there is no room. Measure them or keep them on the labelled reel.
What do the letters X, Y and Z mean in EIA-96 codes?
They are multipliers below 1: X (or S) is ×0.1, Y (or R) is ×0.01 and Z is ×0.001. 68X is 499 × 0.1 = 49.9 Ω.
Is there an in-depth guide to the SMD Resistor Code Calculator?
Yes. “SMD Resistor Codes Explained: 3-Digit, 4-Digit and EIA-96” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
People also search for
- smd resistor 103 value
- what does 4r7 mean on a resistor
- eia-96 resistor code chart
- 01c smd resistor value
- 4 digit smd resistor code 1002
- r010 current sense resistor
- 68x smd resistor
- how to read surface mount resistor codes
Related Tools You May Like
Free, in-browser tools that pair well with this one.