Resistor Color Code Calculator
Decode 4, 5, or 6 band axial resistors
Required Parameters
Reverse Lookup
Enter resistance value → get color bands
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Quick Answer
Read resistor color codes left to right: the first 2–3 bands are significant digits, the next band is the multiplier (number of zeros), and the last band indicates tolerance. Gold = ±5%, Silver = ±10%, Brown = ±1%. Example: Brown-Black-Red-Gold = 10 × 100 = 1kΩ ±5%.
Resistor Color Code Calculator
Use this interactive tool to decode 4-band, 5-band, and 6-band axial resistor color codes into resistance value, tolerance, and temperature coefficient.
How to Read Resistor Color Codes
Step 1: Identify the Reading Direction
Resistors have colored bands painted on them. You need to determine which end to start reading from:
- Look for a gap — There is usually a larger space before the tolerance band. Start reading from the opposite end.
- The metallic band — Gold and Silver are always tolerance bands, so they should be at the end.
- First band near the edge — The first significant band is typically placed closest to one end of the resistor body.
If you're still unsure, use a multimeter to verify your reading direction. Our Reverse Lookup tool can also help — enter the measured value and compare the color output.
Step 2: Decode Each Band
Each color corresponds to a specific number, multiplier, or tolerance value. The standard mapping (per IEC 60062) is:
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 Ω | — |
| Brown | 1 | ×10 Ω | ±1% |
| Red | 2 | ×100 Ω | ±2% |
| Orange | 3 | ×1 kΩ | ±3% |
| Yellow | 4 | ×10 kΩ | ±4% |
| Green | 5 | ×100 kΩ | ±0.5% |
| Blue | 6 | ×1 MΩ | ±0.25% |
| Violet | 7 | ×10 MΩ | ±0.1% |
| Gray | 8 | ×100 MΩ | ±0.05% |
| White | 9 | ×1 GΩ | — |
| Gold | — | ×0.1 Ω | ±5% |
| Silver | — | ×0.01 Ω | ±10% |
4-Band Resistor Color Code
The most common type. The formula is:
Resistance = (10 × Band1 + Band2) × Multiplier ± Tolerance
Example: Brown-Black-Red-Gold
- Brown = 1 (first digit)
- Black = 0 (second digit)
- Red = ×100 (multiplier)
- Gold = ±5% (tolerance)
Result: 10 × 100 = 1,000 Ω = 1 kΩ ±5%
This means the actual resistance is between 950 Ω and 1,050 Ω.
5-Band Resistor Color Code
Used for precision resistors (1% or better). Adds an extra significant digit:
Resistance = (100 × Band1 + 10 × Band2 + Band3) × Multiplier ± Tolerance
Example: Brown-Black-Black-Brown-Brown
- Brown = 1 (first digit)
- Black = 0 (second digit)
- Black = 0 (third digit)
- Brown = ×10 (multiplier)
- Brown = ±1% (tolerance)
Result: 100 × 10 = 1,000 Ω = 1 kΩ ±1%
With 1% tolerance, the actual value is between 990 Ω and 1,010 Ω — ten times more precise than the 4-band equivalent.
6-Band Resistor Color Code
6-band resistors include everything from the 5-band format plus a Temperature Coefficient (TCR) band:
| Color | TCR (ppm/°C) |
|---|---|
| Brown | 100 |
| Red | 50 |
| Orange | 15 |
| Yellow | 25 |
| Blue | 10 |
| Violet | 5 |
The TCR tells you how much resistance changes with temperature:
R(T) = R₀ × [1 + TCR × (T − T₀)]
For example, a 1 kΩ resistor with 50 ppm/°C TCR will change by only 0.05 Ω per degree — critical in precision measurement circuits.
Common Resistor Value Color Codes
What is the 10k resistor color code?
- 4-band: Brown (1) → Black (0) → Orange (×1k) → Gold (±5%)
- 5-band: Brown (1) → Black (0) → Black (0) → Red (×100) → Brown (±1%)
What is the 4.7k resistor color code?
- 4-band: Yellow (4) → Violet (7) → Red (×100) → Gold (±5%)
- 5-band: Yellow (4) → Violet (7) → Black (0) → Brown (×10) → Brown (±1%)
What is the 220 Ohm resistor color code?
- 4-band: Red (2) → Red (2) → Brown (×10) → Gold (±5%)
- 5-band: Red (2) → Red (2) → Black (0) → Black (×1) → Brown (±1%)
What is the 1M Ohm resistor color code?
- 4-band: Brown (1) → Black (0) → Green (×100k) → Gold (±5%)
- 5-band: Brown (1) → Black (0) → Black (0) → Orange (×1k) → Brown (±1%)
Related Tools
- SMD Resistor Code Decoder — Decode surface-mount resistor markings
- Resistor Calculator — Combine decoded resistors in series or parallel
- Ohm's Law Calculator — Apply decoded values in circuit calculations
- LED Resistor Calculator — Use the identified resistor in LED circuits
Common Mistakes to Avoid
- Reading from the wrong end — Always start from the grouped bands, not the tolerance band.
- Confusing Gray and Silver — Gray is a digit (8), Silver is a tolerance (±10%) or multiplier (×0.01).
- Ignoring the tolerance band — A "470Ω ±5%" and "470Ω ±1%" resistor look almost identical but have very different applications.
- Using color codes for SMD — Surface-mount resistors use numeric codes (e.g., "103" = 10kΩ), not color bands. Use our SMD Resistor Code Calculator instead.
When to Use a Multimeter Instead
Color codes are great for quick identification, but always verify with a multimeter when:
- The resistor is old or discolored (heat can alter band colors)
- You need precision better than the stated tolerance
- The band count is ambiguous (is it 4-band or 5-band?)
- You're working with safety-critical circuits
Industry Standards
- IEC 60062 — Marking codes for resistors and capacitors
- IEC 60115-1 — Fixed resistors for use in electronic equipment
- MIL-PRF-55342 — Fixed resistors, chip, established reliability
- EIA Publication 330 — The International Electrotechnical Commission standard for color coding
Design Notes
The resistor color code system was developed in the 1920s per IEC 60062 to mark axial-lead resistors too small for printed numbers. Modern practice uses 4-band for 5%/10% resistors (E12/E24 series) and 5-band for 1% precision (E96 series). 6-band adds a temperature coefficient band for high-stability applications. Metal film resistors are typically blue/green body with 5 bands; carbon film are beige/tan with 4 bands.
Common Mistakes
- 1
Reading the bands in the wrong direction — always start from the end with grouped bands. The metallic tolerance band (Gold/Silver) is always last.
- 2
Confusing the multiplier band with a digit band — the multiplier represents powers of 10, not an additional digit.
- 3
Ignoring the tolerance band — a ±20% 1kΩ resistor could actually be anywhere from 800Ω to 1200Ω.
- 4
Using a 4-band decoding method on a 5-band resistor — count bands carefully before decoding.
Engineering Handbox
1. Band 1 (Brown) = 1 2. Band 2 (Black) = 0 3. Significant digits = 10 4. Multiplier (Red) = ×100 5. Resistance = 10 × 100 = 1000Ω 6. Tolerance (Gold) = ±5%
Knowledge Base
How do I read a 4-band resistor color code?
Read from left to right: Band 1 = first digit, Band 2 = second digit, Band 3 = multiplier, Band 4 = tolerance. For example, Brown-Black-Red-Gold = 10 × 100 = 1kΩ ±5%.
What is the 10k resistor color code?
For a 4-band 10kΩ resistor: Brown (1), Black (0), Orange (×1k), Gold (±5%). For 5-band: Brown (1), Black (0), Black (0), Red (×100), Brown (±1%).
What does the 4th band on a resistor mean?
The 4th band indicates tolerance — the accuracy range of the resistance value. Gold = ±5%, Silver = ±10%, Brown = ±1%. No band means ±20%.
How do I know which end to start reading from?
Look for a gap between bands. The larger space is before the tolerance band. The grouped bands (closer together) mark the starting end. Metallic bands (Gold/Silver) are always on the tolerance end.
What is the difference between 4-band and 5-band resistors?
4-band resistors have 2 significant digits (e.g., 47 × multiplier). 5-band resistors have 3 significant digits (e.g., 470 × multiplier), allowing more precise values like 47.5kΩ.
What does the 6th band on a resistor indicate?
The 6th band shows the Temperature Coefficient of Resistance (TCR) in ppm/°C. Brown = 100 ppm/°C, Red = 50 ppm/°C, Blue = 10 ppm/°C. It tells you how much the resistance changes with temperature.
What is the color code for a 220 Ohm resistor?
4-band: Red (2), Red (2), Brown (×10), Gold (±5%). 5-band: Red (2), Red (2), Black (0), Black (×1), Brown (±1%).
What is a good mnemonic for remembering resistor color codes?
A popular mnemonic is 'BB ROY of Great Britain has a Very Good Wife' — Black (0), Brown (1), Red (2), Orange (3), Yellow (4), Green (5), Blue (6), Violet (7), Grey (8), White (9).
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