How to use the smd resistor code calculator
- Type the code printed on the resistor, such as 472 or 1002. Put one code on each line to decode a list.
- For a value with a decimal, use the R form, for example 4R7 for 4.7 ohms.
- For small 1 percent parts, type the EIA-96 code of two digits and a letter, such as 01A.
- Read the value in ohms, kilohms or megohms, and the format the page used.
Formula
3 digits: ohms = first two digits x 10 to the power of the third digit
4 digits: ohms = first three digits x 10 to the power of the fourth digit
R code: the R is the decimal point
EIA-96: ohms = table value for the two digits x the multiplier for the letter
The last digit is a count of zeros in the digit codes. The EIA-96 two digits pick one of 96 values from a table, and the letter gives the multiplier, such as A for 1, B for 10 and C for 100.
Codes 472, 1002, 4R7 and 01A
Code 472 is 47 followed by 2 zeros, which is 4,700 ohms or 4.7 kilohms. Code 1002 is 100 followed by 2 zeros, which is 10,000 ohms or 10 kilohms. The R code 4R7 is 4.7 ohms.
In the EIA-96 form, 01 is the first table value, 100, and the letter A means times 1, so 01A is 100 ohms. The letter B means times 10, so 01B is 1,000 ohms, and 25C is 178 x 100 = 17,800 ohms. A code of 000 or 0R is a jumper of 0 ohms.
Telling the formats apart
A code with only digits is read as 3 or 4 digits. A code of two digits and a letter, such as 01A, is read as EIA-96. An R anywhere in the code marks a decimal. These rules cover most chips, but some makers use their own marking, so a code that looks odd may follow a different convention.
If the value matters, measure the part with a meter, out of the circuit if you can. Resistors in a circuit can read lower than their marked value because other parts form a second path for the meter current.
Related electronics tools
Capacitors on the same board use another code, which the Capacitor Code Calculator reads. Pair resistors with the Voltage Divider Calculator, check current with the Ohm's Law Calculator, or read through-hole parts with the Resistor Color Code Calculator.
Assumptions and limits
- The EIA-96 table of 96 values is used for two digit and letter codes.
- The letters Y and R, X and S, and H and B are accepted as the same multipliers.
- Tolerance and power rating are not part of the code and are not shown.
- Nothing is uploaded. Decoding runs in your browser.
Frequently asked questions
What does 472 mean on an SMD resistor?
It means 47 followed by 2 zeros, which is 4,700 ohms or 4.7 kilohms. The last digit is the number of zeros.
How do I read a code like 01A?
It is an EIA-96 code. The digits 01 pick the first value in a table of 96, which is 100, and the letter A means multiply by 1, so the value is 100 ohms.
What is an R in a resistor code?
The R takes the place of the decimal point. The code 4R7 is 4.7 ohms, and R22 is 0.22 ohms.
What does a resistor marked 000 do?
It is a zero ohm link, often used as a jumper on a circuit board. The page shows it as 0 ohms.