Maker Tools
Resistor Color Code Calculator
Read any resistor both directions. Pick the colored bands to get resistance, tolerance and temperature coefficient, type a value to see its bands, or decode an SMD or EIA-96 code. The resistor diagram updates as you go.
How to read resistor color codes
A through-hole resistor prints its value as colored bands. Reading left to right, the first bands are significant digits, the next band is a decimal multiplier (a power of ten), and the band after that is the tolerance. A 4-band resistor gives you two digit bands, one multiplier, and one tolerance. A 5-band resistor adds a third digit for tighter precision, and a 6-band resistor tacks on a temperature-coefficient band (ppm/K) at the end.
Each color maps to a fixed value: black is 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8 and white 9. The same colors act as multipliers (brown is x10, red x100, and so on), while gold and silver mean x0.1 and x0.01 in the multiplier band. In the tolerance band, brown is 1%, red 2%, gold 5% and silver 10%. So brown, black, red, gold reads as 1, 0, times 100, at 5%, which is 1000 Ω or 1 kΩ.
Band order and the gold trick
Resistors are not marked with an arrow, so orientation matters. The tolerance band usually sits slightly apart from the rest, and gold or silver almost always marks the tolerance end, so keep those on the right. If you read the resistance backwards you will often land on an absurd value like 47 GΩ, which is a good hint to flip the part around.
SMD resistor codes
Surface-mount resistors are too small for bands, so they use printed codes. A 3-digit code like 472 means the first two digits (47) followed by that many zeros (two), giving 4700 Ω. A 4-digit code like 4702 uses three significant digits plus a multiplier, so 470 with two zeros is 47 kΩ. The letter R marks a decimal point for sub-100-ohm parts: 4R7 is 4.7 Ω. Precision 1% parts use the EIA-96 system, a two-digit lookup code plus a letter multiplier, where 01A decodes to 100 Ω.
E-series preferred values
Resistors are not made in every possible value. They follow the E-series: E12 (12 values per decade, 10% parts), E24 (24 values, 5% parts) and E96 (96 values, 1% parts). This calculator flags whether your value is a standard E24 part and suggests the nearest stock value, which saves you designing around a resistance nobody actually sells.
Frequently asked questions
How do I read a resistor with 4 color bands?
Read left to right with the tolerance band (usually gold or silver) on the right. The first two bands are significant digits, the third is the multiplier (number of zeros), and the fourth is the tolerance. For example brown, black, red, gold is 1, 0, times 100, at 5%, which is 1000 ohms or 1 kilohm.
What is the difference between 4-band, 5-band and 6-band resistors?
A 4-band resistor has two digit bands, so it carries two significant figures. A 5-band resistor adds a third digit band for tighter 1% precision. A 6-band resistor is a 5-band part plus a temperature-coefficient band (ppm/K) at the end.
Which end of the resistor do I start reading from?
Resistors have no arrow, so orientation matters. The tolerance band sits slightly apart from the digit bands, and gold or silver almost always marks the tolerance end, so keep those colors on the right. If your reading gives an absurd value, flip the part around and read it the other way.
How do I decode an SMD resistor code?
A 3-digit code like 472 is two digits (47) followed by that many zeros (two), giving 4700 ohms. A 4-digit code like 4702 is three digits (470) plus a multiplier, giving 47 kilohms. An R marks a decimal point, so 4R7 is 4.7 ohms, and the EIA-96 system uses a two-digit lookup plus a letter multiplier for 1% parts, where 01A is 100 ohms.
What do the E12, E24 and E96 series mean?
Resistors are only made in preferred values, grouped into E-series per decade. E12 has 12 values and covers 10% parts, E24 has 24 values for 5% parts, and E96 has 96 values for 1% parts. This calculator flags whether your value is a standard E24 part and suggests the nearest stock value.
How do I convert a resistance value back into color bands?
Use the Value to bands mode: type the resistance, pick the unit (ohms, kilohms, or megohms), and choose 4, 5, or 6 bands. The tool shows the color bands and the nearest value that can actually be represented at that band count.
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