SMD Resistor Code Calculator

How to use

1. 1Pick Decode mode to read a code, or Build mode to synthesise codes from a target resistance.
2. 2In Decode, type the alphanumeric marking from the resistor (3-digit, 4-digit, R-notation like 4R7, or EIA-96 like 01C) and read the resistance, tolerance, and significant digits.
3. 3In Build, type a target value such as 4.7k, 470, or 1M and copy the 3-digit, 4-digit, R-notation, or EIA-96 code that represents it.
4. 4Use the example buttons to load a known code and confirm the decoder is reading it correctly.
5. 5Consult the EIA-96 multiplier table at the bottom to read codes by hand when you only have a magnifying glass.

About this tool

SMD Resistor Code Calculator reads the cryptic alphanumeric markings printed on surface-mount chip resistors and converts them to a resistance value, and synthesises the markings back from any target value. Unlike axial-lead resistors which use four to six color bands, SMD parts use compact codes that fit on packages as small as 0402 or 0201. The decoder handles every common encoding: 3-digit codes (two significant digits with a decimal-power multiplier, typically ±5%, so 472 means 47 × 10² = 4.7 kΩ); 4-digit codes (three significant digits with a decimal multiplier, typically ±1%, so 4702 means 470 × 10² = 47 kΩ); R-notation where the letter R replaces a decimal point and is used for sub-100 Ω values (4R7 = 4.7 Ω, R47 = 0.47 Ω, 1R0 = 1.0 Ω); EIA-96 codes where two digits select a position on the 96-value E96 base series and a letter (Z, Y/R, X/S, A, B/H, C, D, E, F) applies a power-of-ten multiplier (01C = 100 × 10² = 10 kΩ, 68X = 499 × 0.1 = 49.9 Ω); and the zero-ohm jumper marked 0, 00, 000, or 0000 which is a wire link rather than a resistor. Encode mode runs the math in reverse: type a value like 4.7k, 470, 1M, 1k2, or R47 and the tool synthesises every standard code that represents it, marking impossible encodings as not representable rather than guessing. A reference table shows every EIA-96 multiplier letter with an example so you can sight-read codes off a board without checking a datasheet. Everything runs in your browser; no codes or values are uploaded.

Free to use. Works in your browser. No signup, no login.