Resistor & Capacitor Code Calculator

Decode colour bands and SMD markings on resistors and capacitors

Resistor Color Code Calculator

Select band colors to decode resistance values. Supports standard 4-band and precision 5-band resistors.

Band 1

Band 2

Band 3

Multiplier

Tolerance

Resistance 100 Ω

Tolerance ±5%

Min Value 95 Ω

Max Value 105 Ω

SMD Resistor Code Decoder

Surface-mount resistors are marked with digits instead of colour bands. Enter a marking to decode it — 3-digit (103), 4-digit (1002), R-notation decimals (4R7) and EIA-96 codes (68C) are all recognised automatically.

SMD Marking

3-digit: two significant digits plus a power-of-ten multiplier — 103 = 10 × 10³ = 10 kΩ. Usually ±5%.
4-digit: three significant digits plus a multiplier — 1002 = 100 × 10² = 10 kΩ. Usually ±1%.
R notation: the R marks the decimal point — 4R7 = 4.7 Ω, R22 = 0.22 Ω.
EIA-96: two digits index a 1% E96 value, the letter is the multiplier — 68C = 499 × 100 = 49.9 kΩ.
Jumpers: 0, 00 and 000 are zero-ohm links, not resistors.

Capacitor SMD Code Decoder

Enter a 3-digit or 4-digit SMD capacitor marking code to decode the capacitance value.

SMD Code

Reading Resistor Colour Codes

Axial resistors carry their value as a set of painted bands. Hold the resistor so the band group sits to the left and the lone tolerance band — usually gold or silver, and separated by a wider gap — sits to the right. On a 4-band part the first two bands are significant digits, the third is the power-of-ten multiplier and the fourth is tolerance. On a 5-band precision part you get three significant digits before the multiplier, which is why 5-band resistors can express values like 4.87 kΩ that 4-band coding cannot.

Why the tolerance range matters

The calculator shows minimum and maximum as well as nominal, because that spread is what actually lands in your circuit. A ±5% 10 kΩ resistor is anywhere from 9.5 kΩ to 10.5 kΩ, which is harmless in a pull-up but significant in a divider, a timing network or a current-sense position. If a measured part sits outside its printed range it has drifted — common in anything that has run hot, and a frequent find on old boards alongside tired electrolytics.

SMD markings: four different systems

Surface-mount resistors are printed, not banded, and four schemes are in circulation. Three-digit codes give two digits plus a multiplier, so 103 is 10 kΩ. Four-digit codes give three digits plus a multiplier for 1% parts, so 1002 is 10 kΩ as well. R-notation uses the letter R as a decimal point, so 4R7 is 4.7 Ω and R22 is 0.22 Ω. EIA-96 packs 1% values into two digits plus a multiplier letter, so 68C looks like a nonsense marking until you know that code 68 means 499 and C means ×100 — 49.9 kΩ. A bare 0 or 000 is a zero-ohm jumper link, not a fault.

Capacitor codes read in picofarads

Ceramic and film capacitors use the same digits-plus-multiplier idea, but the result is always in picofarads. The classic 104 is 10 followed by four zeros — 100,000 pF, which is 100 nF or 0.1 µF, the decoupling capacitor you will find beside almost every logic IC ever made. 223 is 22 nF, 471 is 470 pF. Four-digit codes work identically with three significant figures. Note that the code carries no voltage rating and no dielectric type, so always check the physical part or its datasheet before ordering a replacement — a same-value X7R and Y5V behave very differently over temperature.

Working on a supply rail rather than a single part? The Ohm’s law calculator will size the dissipation, and the recap reference lists verified capacitor values for classic mainboards.