Resistor Color Code Calculator
A resistor color code calculator decodes the colored bands on a resistor to determine its resistance value in ohms, or converts a known resistance value back to its color band sequence. Select your band colors in the panel to get an instant result, or enter a resistance value to find its color bands.
What Is a Resistor Color Code?
A resistor color code is a system of painted bands on a resistor body used to indicate its resistance value and tolerance. Since resistors are too small to print readable numbers directly, standardized color codes allow technicians and engineers to identify values quickly. The system was introduced by the Radio Manufacturers' Association and is now governed by the EIA resistor marking standard, which defines the color-to-digit mapping used worldwide.
Each color corresponds to a digit (0–9), a multiplier value, a tolerance percentage, and in the case of 6-band resistors, a temperature coefficient. Understanding this system is fundamental to electronics work, from reading circuit diagrams to building and repairing circuits. Use the calculator on the left to decode any 4-band, 5-band, or 6-band resistor instantly. For more on Ohm's Law and how resistance relates to voltage and current, see our Ohms Law Calculator.
Resistor Color Code Chart
| Color | Digit | Multiplier | Tolerance | Temp. Coeff. (ppm/°C) |
|---|---|---|---|---|
| Black | 0 | ×1 | — | 250 |
| Brown | 1 | ×10 | ±1% | 100 |
| Red | 2 | ×100 | ±2% | 50 |
| Orange | 3 | ×1 kΩ | ±3% | 15 |
| Yellow | 4 | ×10 kΩ | ±4% | 25 |
| Green | 5 | ×100 kΩ | ±0.5% | 20 |
| Blue | 6 | ×1 MΩ | ±0.25% | 10 |
| Violet | 7 | ×10 MΩ | ±0.1% | 5 |
| Grey | 8 | ×100 MΩ | ±0.05% | 1 |
| White | 9 | ×1 GΩ | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
How to Read Resistor Color Bands
Hold the resistor so the tolerance band (gold or silver) is on the right. Read from left to right. The number of bands determines how the digits combine with the multiplier.
4-Band Resistors
The most common type. Bands 1 and 2 are the first and second significant digits. Band 3 is the multiplier. Band 4 is the tolerance. Example: Yellow (4), Violet (7), Red (×100), Gold (±5%) = 4,700 Ω ±5% = 4.7 kΩ ±5%.
5-Band Resistors
Used for precision resistors. Bands 1, 2, and 3 are three significant digits. Band 4 is the multiplier. Band 5 is the tolerance. Example: Red (2), Red (2), Black (0), Orange (×1 kΩ), Brown (±1%) = 220,000 Ω ±1% = 220 kΩ ±1%.
6-Band Resistors (Temperature Coefficient)
The same as 5-band but with an additional 6th band indicating the temperature coefficient in parts per million per degree Celsius (ppm/°C). A Brown 6th band means 100 ppm/°C, meaning the resistance changes by 100 ohms per million ohms per degree Celsius temperature change. These are used in precision circuits where temperature stability is critical.
How to Calculate Resistance from Colors
The resistor color code formula is straightforward once you know the digit and multiplier values for each color.
Step-by-Step Example
For a 4-band resistor with bands: Orange, White, Brown, Gold:
- Step 1 — Identify Band 1 digit: Orange = 3
- Step 2 — Identify Band 2 digit: White = 9
- Step 3 — Combine: 39 (two-digit significand)
- Step 4 — Apply multiplier: Brown = ×10, so 39 × 10 = 390 Ω
- Step 5 — Note tolerance: Gold = ±5%, so range is 370.5 Ω to 409.5 Ω
The result is 390 Ω ±5%. Use the calculator on the left to verify any combination instantly.
Tolerance Band Explained
The tolerance band tells you how close the actual resistance can be to the stated value. A ±5% resistor rated at 1 kΩ could have an actual resistance anywhere between 950 Ω and 1,050 Ω. Choosing the right tolerance depends on the circuit's sensitivity to resistance variation.
Gold (±5%)
The most common tolerance for general-purpose resistors. Suitable for most non-critical applications including LED current limiting, pull-up/pull-down resistors, and basic voltage dividers.
Silver (±10%)
Less common in modern electronics. Found in older or lower-cost components. Only appropriate where resistance variation has minimal effect on circuit performance.
Brown (±1%)
A precision tolerance used in measurement circuits, instrumentation, and feedback networks where accurate resistance values are required. Brown-band resistors are 5-band components with three significant digits. For circuits involving motor control calculations, see our Motor FLA Calculator which relies on accurate component values.
Standard Resistor Values (E12, E24 Series)
Resistors are manufactured in standardized value series to keep the number of distinct values manageable while covering all practical ranges. The E12 series has 12 values per decade (for ±10% tolerance resistors): 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2. The E24 series has 24 values per decade (for ±5% tolerance): includes all E12 values plus 1.1, 1.3, 1.6, 2.0, 2.4, 3.0, 3.6, 4.3, 5.1, 6.2, 7.5, 9.1.
For precision applications, E48 (±2%) and E96 (±1%) series exist with more closely spaced values. When converting a calculated resistance to color bands using the Value to Color mode, the result will be rounded to the nearest representable value. For electronics converters and unit conversions, see our energy converter tool. The Electronics Tutorials resistor color codes guide provides additional reference material on resistor types and applications. For a comprehensive component reference, the Digi-Key resistor color code reference chart is widely used in the industry.
Frequently Asked Questions
How to read a resistor color code?
Hold the resistor with the tolerance band (gold or silver) on the right. Read bands from left to right. For a 4-band resistor, the first two bands are digits, the third is the multiplier, and the fourth is tolerance. Combine the digits, multiply by the multiplier value, and apply the tolerance. For example: Brown, Black, Orange, Gold = 10 × 1000 ± 5% = 10 kΩ ±5%.
What do the colored bands on a resistor mean?
Each color corresponds to a number (0–9), a multiplier, and optionally a tolerance and temperature coefficient. The bands encode the resistance value without needing printed text. Black is 0, brown is 1, red is 2, orange is 3, yellow is 4, green is 5, blue is 6, violet is 7, grey is 8, and white is 9. Gold and silver are used as multipliers (×0.1 and ×0.01) and tolerance bands (±5% and ±10%).
What is the tolerance band on a resistor?
The tolerance band indicates how much the actual resistance can deviate from the stated value. A gold band means ±5%, silver means ±10%, brown means ±1%, and red means ±2%. For a 1 kΩ resistor with gold tolerance, the actual resistance will be between 950 Ω and 1,050 Ω. Precision circuits typically require ±1% or better tolerance resistors.
How do I tell which end to start reading from?
Start reading from the end closest to the first band. The tolerance band (gold or silver) is always on the right side when reading left to right. If both ends look equally spaced, look for the gold or silver band — that is always the tolerance and goes on the right. On 5-band and 6-band resistors, the bands may be more evenly spaced, making orientation harder; in that case, the first band is always closest to one end of the component.
What is the difference between a 4-band and 5-band resistor?
A 4-band resistor uses two significant digits plus a multiplier and tolerance, providing values to 2 significant figures (e.g., 4.7 kΩ). A 5-band resistor uses three significant digits plus a multiplier and tolerance, giving values to 3 significant figures (e.g., 4.70 kΩ). 5-band resistors are more precise and are commonly used in 1% tolerance components. For most general circuits, 4-band resistors are sufficient.