Resistor Calculator
Calculate resistor values from color bands and vice versa
Resistor Preview
ppm/°C
Enter value in ohms (e.g., 4700 for 4.7kΩ)
Resistance Value
±%
Exact Value
Min Value
Max Value
Color Code
Color Code Reference
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
|
|
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About Resistor Calculator
The Resistor Calculator is an essential electronics tool that helps engineers, hobbyists, and students decode resistor color codes and calculate resistance values. Understanding resistor color bands is fundamental to working with electronic circuits.
How Resistor Color Codes Work
Color Code System
Resistors use colored bands to indicate their resistance value and tolerance. Each color represents a specific number or multiplier.
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | 1Ω (×1) | - |
| Brown | 1 | 10Ω (×10) | ±1% |
| Red | 2 | 100Ω (×100) | ±2% |
| Orange | 3 | 1kΩ (×1,000) | ±0.05% |
| Yellow | 4 | 10kΩ (×10,000) | ±0.02% |
| Green | 5 | 100kΩ (×100,000) | ±0.5% |
| Blue | 6 | 1MΩ (×1,000,000) | ±0.25% |
| Violet | 7 | 10MΩ (×10,000,000) | ±0.1% |
| Gray | 8 | 100MΩ (×100,000,000) | ±0.01% |
| White | 9 | 1GΩ (×1,000,000,000) | - |
| Gold | - | 0.1Ω (×0.1) | ±5% |
| Silver | - | 0.01Ω (×0.01) | ±10% |
| None | - | - | ±20% |
4-Band Resistors
The most common type of resistor:
- Band 1: First significant digit
- Band 2: Second significant digit
- Band 3: Multiplier
- Band 4: Tolerance
Example: Red-Violet-Orange-Gold = 27 × 1,000 = 27,000Ω (27kΩ) ±5%
5-Band Resistors
More precise resistors with an additional digit:
- Band 1: First significant digit
- Band 2: Second significant digit
- Band 3: Third significant digit
- Band 4: Multiplier
- Band 5: Tolerance
Example: Brown-Black-Black-Red-Brown = 100 × 100 = 10,000Ω (10kΩ) ±1%
6-Band Resistors
High-precision resistors with temperature coefficient:
- Band 1-3: Three significant digits
- Band 4: Multiplier
- Band 5: Tolerance
- Band 6: Temperature coefficient (ppm/°C)
Reading Resistor Color Codes
Tips for Identification
- Find the tolerance band: Usually Gold, Silver, or wider/spaced band
- Orient correctly: Tolerance band should be on the right
- Read left to right: Start from the band closest to the edge
- Use good lighting: Colors can be hard to distinguish in poor light
Common Mistakes
- Confusing Red and Orange
- Mixing up Blue and Violet
- Reading bands in reverse order
- Missing the tolerance band entirely
Standard Resistor Values (E-Series)
E12 Series (10% tolerance)
1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
E24 Series (5% tolerance)
Includes 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
E96 Series (1% tolerance)
96 values per decade for high-precision applications
Frequently Asked Questions
What if there's no tolerance band?
No tolerance band typically means ±20% tolerance (very old or carbon composition resistors).
How do I know if it's a 4-band or 5-band resistor?
The gap between the multiplier and tolerance bands is usually larger. 5-band resistors also tend to have more precise tolerance markings.
Why do resistors have color codes?
Color codes are easier to read on small components from any angle, unlike printed numbers which might be obscured.
What is the temperature coefficient?
It indicates how much the resistance changes with temperature, measured in parts per million per degree Celsius (ppm/°C).
Note: This calculator provides standard resistor color code values. Always verify critical resistor values with a multimeter for precision applications.
Reading Resistor Mnemonic
Common memory aid for color order:
Bad Beer Rots Our Young Guts But Vodka Goes Well
Black (0), Brown (1), Red (2), Orange (3), Yellow (4), Green (5), Blue (6), Violet (7), Gray (8), White (9)