Resistor Calculator
Color Code Decoder, Series/Parallel Calculator & Conductor Resistance - Complete Resistor Tools
🔌 Pro Tips for Resistor Calculations:
Resistor color codes standardized by IEC 60062. Read left-to-right with spacing gap between 3rd and 4th band. 4-band: 2 significant figures + multiplier + tolerance. 5-band: 3 significant figures + multiplier + tolerance. 6-band adds temperature coefficient. Series = sum all. Parallel = reciprocal sum. Temperature affects resistance (ppm/K).
Resistor Color Code Decoder
✅ Color Code Results:
Parallel Resistor Calculator
✅ Parallel Resistance Results:
Series Resistor Calculator
✅ Series Resistance Results:
Conductor Resistance Calculator
✅ Conductor Resistance Results:
Color Code Reference Tables
Resistor Color Code Chart (IEC 60062):
| Color | Digit Value | Multiplier | Tolerance (±%) | Temp Coeff (ppm/K) |
|---|---|---|---|---|
| Black | 0 | ×1 | — | 250 |
| Brown | 1 | ×10 | ±1% | 100 |
| Red | 2 | ×100 | ±2% | 50 |
| Orange | 3 | ×1K | ±0.05% | 15 |
| Yellow | 4 | ×10K | ±0.02% | 25 |
| Green | 5 | ×100K | ±0.5% | 20 |
| Blue | 6 | ×1M | ±0.25% | 10 |
| Violet | 7 | ×10M | ±0.1% | 5 |
| Grey | 8 | ×100M | ±0.01% | 1 |
| White | 9 | ×1G | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
Material Conductivity Values:
| Material | Conductivity (S/m) | Resistivity (Ω·m) | Common Uses |
|---|---|---|---|
| Copper | 59.6 × 10⁶ | 1.68 × 10⁻⁸ | Wiring, conductors |
| Aluminum | 37.7 × 10⁶ | 2.65 × 10⁻⁸ | Busbars, overhead lines |
| Silver | 62.9 × 10⁶ | 1.59 × 10⁻⁸ | Circuits, contacts |
| Gold | 44.6 × 10⁶ | 2.24 × 10⁻⁸ | Contacts, connectors |
| Constantan | 2.0 × 10⁶ | 5.0 × 10⁻⁷ | Heating elements, sensors |
| Nichrome | 0.1 × 10⁶ | 1.0 × 10⁻⁵ | Heating coils, rheostats |
Common Resistor Configurations:
4-Band Resistor: Standard general-purpose resistor. 2 significant figures + multiplier + tolerance. Typical tolerance ±5% to ±20%.
5-Band Resistor: Precision resistor with 3 significant figures. Increased accuracy. Typical tolerance ±0.1% to ±1%.
6-Band Resistor: Premium precision resistor. Adds temperature coefficient band. Tight tolerance. Used in critical applications.
Reading Direction: Left to right with spacing gap between 3rd and 4th band. Gap indicates direction to read. Always read from correct direction.
5-Band Resistor: Precision resistor with 3 significant figures. Increased accuracy. Typical tolerance ±0.1% to ±1%.
6-Band Resistor: Premium precision resistor. Adds temperature coefficient band. Tight tolerance. Used in critical applications.
Reading Direction: Left to right with spacing gap between 3rd and 4th band. Gap indicates direction to read. Always read from correct direction.
🔌 Understanding Resistors in Electrical Circuits
What is Resistance?:
Resistance opposes electrical current flow, measured in ohms (Ω). Formula: \(R = V / I\) (Ohm's Law). Resistors are passive components dissipating energy as heat. Physical materials have intrinsic resistivity affecting their resistance. Temperature affects resistance (positive or negative temperature coefficient).
Resistor Circuit Configurations:- Series: R_total = R1 + R2 + R3. Same current. Voltages add.
- Parallel: 1/R_total = 1/R1 + 1/R2 + 1/R3. Same voltage. Currents add.
- Mixed: Combinations of series and parallel. Analyze section by section.
- Fixed Resistors: Predetermined resistance. Most common type. Used in circuits, networks.
- Variable Resistors: Potentiometers, rheostats. Adjustable resistance for tuning.
- Wirewound Resistors: High power dissipation. Precise values. Heating applications.
- Thin-film Resistors: High precision (±0.01%). Temperature stable. Expensive.
- Carbon Composition: General purpose. Cost-effective. Tolerance ±5-20%.
- Power dissipated: \(P = I^2 R = V^2 / R = VI\) (watts)
- Resistor ratings: 1/8W, 1/4W, 1/2W, 1W, 2W, etc.
- Must select resistor rated for application power
- Derating required at elevated temperatures
- Safety margin: typically 2× calculated power
- Determine required resistance value from circuit design
- Select appropriate tolerance for application accuracy
- Choose power rating for heat dissipation
- Consider temperature coefficient stability
- Verify availability (standard E-series values)
- Factor in cost vs. performance requirements
❓ Frequently Asked Questions
How do you read a four-band resistor color code?
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First band (largest): first digit. Second band: second digit. Third band (gap): multiplier. Fourth band: tolerance. Example: Brown-Black-Red-Gold = 1-0-×100-±5% = 1000Ω ±5% (1kΩ ±5%).
What's the difference between tolerance bands?
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Gold (±5%): general purpose. Silver (±10%): less precise. Brown (±1%): precision. Red (±2%): medium precision. Orange (±0.05%), Yellow (±0.02%): high precision (expensive). Choose based on circuit requirements and cost constraints.
How do two 100Ω resistors behave in series vs parallel?
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Series: 100Ω + 100Ω = 200Ω total. Parallel: 1/(1/100 + 1/100) = 50Ω total. Series increases resistance. Parallel decreases resistance (always less than smallest resistor).
What does "ppm/K" mean on resistor specs?
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ppm/K = parts per million per Kelvin (temperature coefficient). 100 ppm/K resistor: 0.01% resistance change per °C. Lower values more stable. Precision applications require tight temperature coefficient control.
Why does wire gauge affect resistance?
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Resistance inversely proportional to cross-sectional area. Formula: R = ρL/A. Doubling diameter quadruples area, reducing resistance to 1/4. Thicker wire (lower gauge) = lower resistance = better for power transmission.
What's a standard E-series resistor value?
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E-series standardizes resistor values (E6, E12, E24). E12 common: 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82Ω (×10ⁿ). Reduces manufacturing, ensures availability, simplifies stock keeping. Choose E-series values when possible.
How do you calculate power dissipation in resistors?
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Three formulas (same result): P = I²R, P = V²/R, P = IV. Example: 100Ω resistor, 1A current = 1² × 100 = 100W. Choose resistor rated for this power (use 2× safety margin = select 200W rated resistor).
What's the difference between resistivity and conductivity?
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Resistivity (ρ): opposes current flow (Ω·m). Conductivity (σ): allows current flow (S/m). Inverse relationship: σ = 1/ρ. Copper high conductivity, low resistivity. Nichrome low conductivity, high resistivity. Choose material based on application.