Resistor Color Code Calculator
Resistors are marked with colored bands that encode their resistance value and tolerance. This calculator decodes the standard 4-band color code into an ohm value and tolerance percentage.
Advertisement
Calculator
See your Resistor Color Code Calculator results
Enter your email to unlock results — free forever.
No spam, ever. Unsubscribe at any time.
Advertisement
Formula
R = (D1 × 10 + D2) × 10^M
For a 4-band resistor: the first two bands give the first two significant digits (D1, D2). The third band is the multiplier (power of 10). The fourth band (not entered here) gives tolerance: Gold = ±5%, Silver = ±10%, Brown = ±1%, Red = ±2%. Resistance = (D1×10 + D2) × 10^multiplier ohms.
How to use the Resistor Color Code Calculator
- 1
Enter your band 1 (1st digit)
- 2
Enter your band 2 (2nd digit)
- 3
Enter your band 3 (multiplier)
- 4
Read your results instantly
Results update in real time as you type.
Advertisement
Reading resistor color bands
The color code encodes resistance using a sequence of bands. The mnemonic 'Bad Boys Race Our Young Girls But Violet Generally Wins' gives the order: Black(0), Brown(1), Red(2), Orange(3), Yellow(4), Green(5), Blue(6), Violet(7), Gray(8), White(9).
For a 4-band resistor (most common): Band 1 = first digit, Band 2 = second digit, Band 3 = multiplier (power of 10), Band 4 = tolerance. A resistor with Brown-Black-Orange-Gold: 1-0-×1000-±5% = 10,000Ω = 10kΩ ±5%.
Standard resistor values (E-series)
Resistors don't come in every value — they're manufactured in standard series. The E12 series has 12 values per decade: 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2. With ±10% tolerance, adjacent values overlap in range, covering all possible needs.
The E24 series (24 values per decade, ±5% tolerance) and E96 series (96 values, ±1%) provide finer granularity for precision work. This is why you'll never find a 10.3kΩ resistor in a catalog — the nearest E24 value is 10kΩ or 11kΩ.
Advertisement
5-band and SMD resistors
Precision resistors use 5 bands: three significant digits, multiplier, tolerance. Brown-Black-Black-Red-Brown = 1-0-0-×100-±1% = 10,000Ω = 10kΩ ±1%.
Surface-mount (SMD) resistors are too small for color bands. They use a 3- or 4-digit code: '103' means 10 × 10³ = 10kΩ. '4702' means 470 × 10² = 47kΩ. Letter codes indicate tolerance: F = ±1%, G = ±2%, J = ±5%, K = ±10%.
Tips & Insights
Gold/Silver multiplier bands
Gold multiplier = ×0.1, Silver = ×0.01. These are used for values below 10Ω. Brown-Black-Gold = 1Ω.
Hold the resistor correctly
Tolerance band (Gold/Silver) is usually at the right end. Hold with tolerance band on the right, then read left to right.
Measure with a multimeter
Color codes can fade or be misread. For precision work, always measure with a multimeter on the resistance setting.
Worked Examples
10 kΩ resistor
(1×10 + 0) × 10³ = 10,000Ω = 10kΩ. Brown-Black-Orange with Gold tolerance = 10kΩ ±5%.
470 Ω resistor
(4×10 + 7) × 10¹ = 470Ω. Yellow-Violet-Brown = 470Ω.
Advertisement
Frequently Asked Questions
What do resistor color bands mean?
Each color represents a digit or multiplier. The standard sequence: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9.
What does the tolerance band mean?
The last band gives the accuracy of the marked value. Gold = ±5%, Silver = ±10%, Brown = ±1%, Red = ±2%. A 10kΩ ±5% resistor measures between 9,500Ω and 10,500Ω.
How do I read a 5-band resistor?
Three significant digit bands, then multiplier, then tolerance. Each of the first three bands is a digit; the fourth multiplies by a power of 10.
What are SMD resistor codes?
3-digit: first two digits are significant, third is multiplier exponent. '103' = 10×10³ = 10kΩ. 4-digit: first three are significant, fourth is exponent. '4702' = 470×10² = 47kΩ.
Why can't I find the exact resistor value I need?
Resistors are made in E-series standard values. Use the nearest standard value or combine resistors in series/parallel to achieve non-standard values.
Advertisement