Resistor Color Code Calculator

About the Resistor Color Code Calculator

The Resistor Color Code Calculator decodes through-hole resistor bands into resistance and tolerance. It is a fast way to read a part when the marking is color-based instead of numeric, which is common on older or leaded components. It is especially useful when you want a quick bench-side check without second-guessing the band order.

Select the band colors to see the value in ohms, kilohms, or megohms. The calculator supports 4-band, 5-band, and 6-band resistors, so it covers the common layouts used for general-purpose and precision parts.

It also includes reverse lookup from value to color code, which is useful when you know the target resistance but need to identify the correct band pattern. Nearby standard E-series values are shown as well, so you can quickly compare a measured or planned value against the usual preferred parts. That makes it easier to confirm a part on the bench without hunting through a chart.

When This Page Helps

Use this calculator when you need a resistor value quickly without reading the bands by eye. It is useful for bench work, repairs, and picking standard replacement values, especially when you are matching a replacement part to a measured or marked resistance. That keeps the color bands, tolerance, and target value together while you troubleshoot or swap parts.

How to Use the Inputs

1. Select the number of bands (4, 5, or 6).
2. Click each band and choose the appropriate color.
3. Read the decoded resistance value, tolerance, and range.
4. Use the reverse lookup to find color bands for a known value.
5. Check nearby E12/E24/E96 standard values in the reference table.
6. For 6-band resistors, also decode the temperature coefficient.

Example Calculation

Tips & Best Practices

• Mnemonic: "BB ROY of Great Britain had a Very Good Wife" — Black Brown Red Orange Yellow Green Blue Violet Gray White (0-9).
• Brown resistors (1% tolerance) always have 5 bands — don't confuse them with 4-band.
• Gold and silver multipliers mean values less than 10 Ω (e.g., 4.7 Ω, 0.47 Ω).
• Surface-mount resistors use a 3-digit or 4-digit number code instead of colors.
• Verify questionable readings with a multimeter — faded colors are easily misread.

Color Code Reference

The resistor color code assigns each color a digit value, a multiplier, and optionally a tolerance: - Black (0, ×1, —), Brown (1, ×10, ±1%), Red (2, ×100, ±2%), Orange (3, ×1k, —), Yellow (4, ×10k, —), Green (5, ×100k, ±0.5%), Blue (6, ×1M, ±0.25%), Violet (7, ×10M, ±0.1%), Gray (8, ×100M, ±0.05%), White (9, ×1G, —), Gold (—, ×0.1, ±5%), Silver (—, ×0.01, ±10%).

The tolerance band determines the precision class. Gold (5%) is standard for commercial resistors. Brown (1%) is common for precision work. Green (0.5%), blue (0.25%), and violet (0.1%) are specialty precision grades.

E-Series Standard Values

The E12 series (10% tolerance) values per decade: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82. E24 adds: 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91. E96 (1% tolerance) has 96 geometrically spaced values per decade, going from 100 to 976. These ensure that any design value falls within tolerance of a standard value.

SMD Resistor Codes

Surface-mount resistors use numeric codes. Three-digit code: first two digits are significant, third is the multiplier (number of zeros). Example: 472 = 4700 Ω = 4.7 kΩ. Four-digit code: three significant digits + multiplier. Example: 4702 = 47000 Ω = 47 kΩ. Code 0R47 = 0.47 Ω (R marks the decimal point).

Frequently Asked Questions

• Which end do I read from?

  Start from the band closest to one end of the resistor, because the tolerance band is usually separated from the other bands. Gold and silver are strong clues: they are normally tolerance or multiplier colors, not digit bands. If the resistor is worn or hard to read, the band spacing is often the easiest way to identify the reading direction.

• What's the difference between 4-band and 5-band resistors?

  Four-band resistors use two significant digits, a multiplier, and a tolerance band, so they are common for general-purpose parts. Five-band resistors add a third significant digit, which gives a finer nominal value and is common in precision applications. In practice, the extra digit matters most when you need a tighter tolerance or a more exact standard value.

• What is the 6th band?

  The sixth band indicates the temperature coefficient of resistance, usually in ppm/°C. That value tells you how much the resistance changes as the part warms up or cools down, which matters in precision circuits and temperature-sensitive designs. A lower TCR means the resistor stays more stable as temperature changes.

• What are E-series values?

  E-series are the standard preferred-value sets used for commercial resistors. Each series is spaced so that the values fit the tolerance class: E12 for 10%, E24 for 5%, E48 for 2%, E96 for 1%, and so on. That is why many resistor inventories seem to cluster around the same familiar values.

• Why are gold and silver only on the right?

  Gold and silver are used for multipliers and tolerances, not for significant digits. Since significant digits are read left to right, those colors are placed where the multiplier or tolerance is expected, which is normally on the right side of the resistor. That convention keeps the code readable and avoids ambiguity.

• How do I read a 0 Ω resistor?

  A zero-ohm resistor is often used as a jumper or link on a PCB, even though it looks like a resistor. It typically has a single black band or another manufacturer-specific marking that indicates the near-zero value. The part exists because it can be handled like a component during automated assembly.