SMD Resistor Code Calculator

How It Works

The SMD resistor code is interpreted as follows:

  • For 3-digit codes:
    • If it starts with 'R', the value is in ohms (e.g., 'R10' = 0.10Ω)
    • If 'R' is in the middle, it represents the decimal point (e.g., '1R0' = 1.0Ω)
    • If no 'R', the last digit is the multiplier (e.g., '103' = 10 * 10^3 = 10kΩ)
  • For 4-digit codes:
    • Similar to 3-digit codes, but with an extra precision digit
    • 'R' can be in first, second, or third position to indicate decimal point
    • Without 'R', it follows the same principle as 3-digit codes (e.g., '1002' = 10kΩ)

The calculator converts the result to kΩ or MΩ for values 1000Ω and above.

Frequently Asked Questions

What does SMD Resistor Code Calculator do?

SMD resistor code calculator: convert 3-digit and 4-digit EIA-96 codes to ohm values instantly.

How do I use SMD Resistor Code Calculator?

Type a 3-digit, 4-digit, or R-notation SMD code (e.g. 103, 4R7, R47). The calculator instantly converts it to a resistance value in ohms with the multiplier shown.

Is SMD Resistor Code Calculator free to use?

Yes. This SMD resistor code decoder is free and runs in the browser with no installation needed.

Reading SMD Resistor Codes Quickly

Surface-mount resistors are too small to print a conventional color code, so manufacturers mark them with a printed code on the top surface instead. Three and four digit codes follow a straightforward rule — the first one or two digits are the significant figures and the final digit is the power of ten multiplier. For example, 103 means 10 × 10³ = 10 kΩ, and 4702 means 470 × 10² = 47 kΩ.

When a resistor has a very small value, the letter R stands for the decimal point: 4R7 is 4.7 Ω, R10 is 0.1 Ω, and 1R0 is 1 Ω. Some small-value components instead use codes from the EIA-96 system, where two digits reference a lookup table and a trailing letter sets the multiplier. This calculator handles 3-digit, 4-digit, and R-notation codes automatically, and switches the result to kΩ or MΩ whenever the value grows large enough to be more readable that way.

How to Use

  • Type the code you see on the component into the Enter SMD Code field (e.g. 103, 4702, R47).
  • Click Calculate to decode it into ohms, kilohms, or megaohms instantly.
  • Press Copy to save the result, and use the notes below to double-check your reading.

Tips for Accurate Reading

Clean the component surface and use good lighting — codes are printed in tiny font and can be confused with orientation marks. Check the schematic or the bill of materials when a value seems unusual, since a damaged marking can turn a 4.7 Ω into what looks like 47 Ω. When in doubt, measure the part with an ohmmeter; codes are a labelling aid, not a substitute for verification during troubleshooting.