Decode resistor color bands to find the resistance value and tolerance. Select 4 or 5 color bands to calculate the resistor value in ohms, kilohms, or megohms.
Through-hole resistors use colored bands instead of printed numbers to indicate their resistance value and tolerance. The color code is standardized worldwide (IEC 60062). Knowing how to read it lets electronics hobbyists, technicians, and engineers identify resistors at a glance — though with practice, it becomes almost instinctive.
The most common formats are 4-band (3 significant figures + multiplier + tolerance) and 5-band (3 digits + multiplier + tolerance). Newer or precision resistors may use 5-band; older or general-purpose may be 4-band. The colored bands are read from the side opposite the tolerance band, typically gold or silver (4-band) or brown/red (5-band precision).
The color-to-digit mapping is the same throughout: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9. Multiplier bands extend this with Gold (×0.1) and Silver (×0.01) for resistances below 10 Ω. Tolerance bands use Brown (±1%), Red (±2%), Gold (±5%), Silver (±10%), or none (±20%).
A common 1 kΩ resistor (1000 Ω) is brown-black-red-gold in 4-band: 1, 0, ×100, ±5%. In 5-band it's brown-black-black-brown-brown: 1, 0, 0, ×10, ±1%.
This calculator decodes any combination of color bands to give you the resistance value, tolerance, and the actual range of acceptable values. Useful for identifying unknown resistors, designing circuits, or just learning the color code.
Common applications: hobbyist electronics, circuit prototyping, repair work, education, kit assembly, and any work with through-hole resistors. SMD (surface-mount) resistors use different numerical codes covered separately.
**Scenario:** Brown-Black-Red-Gold. **Calculation:** D1 = 1 (brown), D2 = 0 (black), Multiplier = ×100 (red), Tolerance = ±5% (gold). Value: 10 × 100 = 1,000 Ω. **Result:** 1 kΩ ±5% — actual value 950-1050 Ω. One of the most common resistor values, used in countless circuits as base values for voltage dividers, current limiting, and signal conditioning.
**Scenario:** Yellow-Violet-Black-Yellow-Brown. **Calculation:** D1 = 4 (yellow), D2 = 7 (violet), D3 = 0 (black), Multiplier = ×10,000 (yellow), Tolerance = ±1% (brown). Value: 470 × 10⁴ = 4.7 MΩ ±1%. **Result:** 4.7 MΩ ±1% — actual range 4.653-4.747 MΩ. Used in high-impedance circuits like multimeter input dividers, op-amp feedback, or timer circuits.
**Scenario:** Hobbyist finds an unknown resistor with bands: orange-orange-brown-gold. **Calculation:** D1 = 3 (orange), D2 = 3 (orange), Multiplier = ×10 (brown), Tolerance = ±5% (gold). Value: 33 × 10 = 330 Ω. **Result:** 330 Ω ±5% — actual 313-347 Ω. Common LED current-limiting value. Use a multimeter to confirm if in doubt; precision components can verify the calculation.
**Use color code decoding for:**
- **Hobbyist electronics**: identifying parts in bins. - **Repair work**: finding values on circuit boards. - **Kit assembly**: verifying correct parts. - **Education**: learning electronic components. - **Inventory**: organizing resistor collections. - **Quality control**: visually verifying batches.
**When to use a multimeter instead:**
- **Faded colors**: heat or age can wash out bands. - **Burnt resistors**: changed value indicates damage. - **Mounted in circuit**: parallel paths can confuse readings; remove first. - **Critical applications**: always verify with measurement. - **Unfamiliar codes**: SMD or unusual schemes.
**Reading direction:**
Most 4-band resistors: - Gold/silver = tolerance band (last). - Read from opposite end.
If both ends look similar (e.g., 5-band with brown tolerance), look for: - Larger gap before tolerance band. - Sensible value in E12/E24 standard series.
**Standard E-series values:**
E12 (±10%): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82. E24 (±5%): adds 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91.
These multiply by 10, 100, 1k, 10k, 100k, 1M. So if your decode gives 13 × 100 = 1300 Ω, that's a real E24 value.
If you decode something weird like 67 × 10 = 670 Ω — that's NOT a standard value. You probably read bands wrong; try reversing.
**Power dissipation considerations:**
The color code shows resistance and tolerance but NOT power rating. Physical size indicates power: - 1/8 W: 3.2 × 1.8 mm body. - 1/4 W: 6.5 × 2.5 mm. - 1/2 W: 9.5 × 3.5 mm. - 1 W: 11.5 × 5 mm.
For circuit design, calculate dissipation P = I²R and choose adequate size.
**Common applications:**
- **Hobbyist storage**: organize by value using color bands. - **Repair**: identify replacement part on broken board. - **Education**: teach electronics by reading codes. - **Kit verification**: ensure shipped parts match specifications. - **Old electronics restoration**: vintage devices use color codes.
**Sources of confusion:**
- **Brown vs red**: both reddish; brown has more orange undertone. - **Orange vs red**: orange is brighter; red is deeper. - **Grey vs silver**: grey has visible color; silver is metallic. - **Burnt resistors**: change value; visual code unreliable. - **Carbon composition resistors**: colors can fade with age.
**SMD codes (briefly):**
| Type | Format | Example | |---|---|---| | 3-digit | XYZ → XY × 10^Z | 103 = 10 kΩ | | 4-digit | WXYZ → WXY × 10^Z | 1002 = 10 kΩ | | EIA-96 | XYZ → table + letter | 01A = 100 Ω | | R notation | XRY → X.Y | 4R7 = 4.7 Ω |
**Software/tools:**
- **Color code apps**: iOS/Android scanners. - **Multimeter**: definitive measurement. - **Resistor sorting machines**: industrial. - **CAD libraries**: standard E-series values.
**Pitfalls:**
- **Reading backwards**: gives wrong value. - **Misidentifying tolerance band**: especially in 5-band. - **Confusing similar colors**: brown/red/orange in poor light. - **Assuming all 4-band**: some are 5- or 6-band. - **Ignoring physical condition**: cracked, burnt, or modified resistors. - **Mixing color codes**: SMD uses different system. - **Forgetting parallel resistance in-circuit**: remove for accurate reading.
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Resistance
1.00 kΩ
Tolerance
±5%
Range
950.00 Ω - 1.05 kΩ
| Parameter | Value |
|---|---|
| Resistance | 1.00 kΩ |
| Resistance (exact) | 1,000 Ω |
| Tolerance | ±5% |
| Minimum Value | 950.00 Ω |
| Maximum Value | 1.05 kΩ |
| Band Count | 4-band |
| Color Sequence | Brown, Black, Red |
| Base Value | 10 |
| Multiplier | ×100 |