Decode 4-band resistor color codes to find resistance value, tolerance, and range.
Resistance Value
1 kΩ
Tolerance±5%
Min Value952.38 kΩ
Max Value1.05 kΩ
Band ColorsBrown Black Red Gold
Resistor color codes follow a standard: the first two bands are digit values (0–9), the third is a power-of-10 multiplier, and the fourth represents tolerance (accuracy).
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What is the Resistor Color Code Calculator?
Resistors use a color-coding system to indicate their resistance value in ohms, multiplication factor, and tolerance (accuracy range). Each color represents a digit (0–9), and by reading the bands in order, you can determine the exact resistance without needing specialized equipment. The 4-band code is the most common for standard resistors.
How it works
The first two colored bands are digit values (0–9 each). The third band is a power-of-10 multiplier (×1, ×10, ×100, up to ×10,000,000). The fourth band indicates tolerance—how much the actual value can drift from the nominal rating. The formula is: (first digit × 10 + second digit) × multiplier = resistance in ohms.
Resistance (Ω) = (D1 × 10 + D2) × 10^M
Min Value = Resistance ÷ (1 + Tolerance%/100)
Max Value = Resistance × (1 + Tolerance%/100)
D1 and D2 are the digit values of the first two bands. M is the multiplier exponent (0 for 1, 1 for 10, 2 for 100, etc.). Tolerance converts the nominal value into an acceptable range; a 1% tolerance on a 1 kΩ resistor means the true value falls between 990 Ω and 1010 Ω.
Examples
Input
Result
Notes
Brown Black Red Gold
1 kΩ ± 5%
Digits 1 and 0, multiplied by 100 (Red = 10²), with 5% tolerance range of 950 Ω to 1050 Ω
Red Violet Orange Brown
27 kΩ ± 1%
Digits 2 and 7, multiplied by 1000 (Orange = 10³), with 1% tolerance; high precision resistor
Orange Orange Yellow Silver
33 MΩ ± 10%
Digits 3 and 3, multiplied by 100,000 (Yellow = 10⁴), with 10% tolerance; very high resistance
How to use the Resistor Color Code Calculator
Identify the four colored bands on your resistor, reading from left to right
Look up the first band color in the digit table (0–9) and note the digit
Look up the second band color and note that digit to form a two-digit number
Check the third band against the multiplier table (powers of 10 from 10⁰ to 10⁷)
Identify the fourth band as the tolerance (Brown ±1%, Red ±2%, Gold ±5%, Silver ±10%)
Calculate: (D1 × 10 + D2) × multiplier = resistance in ohms, then convert to kΩ or MΩ if needed
Benefits
Instant decoding—no lookup tables or mental math needed; instant visual feedback
Prevents mistakes—avoids accidentally installing a 47 kΩ when you meant 4.7 kΩ
Determines tolerance—tells you how tight the tolerance spec is, useful for precision circuits
Calculate min/max range—shows you the acceptable variance so you can verify your resistor meets spec
Works offline—purely client-side; no internet required once the page loads
Educational—helps beginners learn the color code system through hands-on practice
Tips & common mistakes
Common mistakes
Reading bands right-to-left instead of left-to-right—always start from the band closest to the wire lead
Confusing the multiplier with the third digit—remember the third band is 10^N, not a digit 0–9
Forgetting the tolerance band—the fourth band is critical for understanding acceptable error margins
Misreading similar colors—Grey and White, Brown and Red can look similar in poor light; verify carefully
Tips
Use a magnifying glass if the bands are small or faded—a 10× loupe is a handy electronics tool
Mark the end closest to the wire lead as 'start'—bands are always read from that end
Double-check with a digital multimeter (DMM) if you have one—an inexpensive meter (~$10) verifies your reading
Keep a color chart on your bench—laminate one or bookmark this tool for quick reference while prototyping
Frequently asked questions
What if my resistor has 5 bands instead of 4?
5-band resistors add a third digit before the multiplier, giving higher precision. Use the first three bands as digits, the fourth as the multiplier, and the fifth as tolerance. This calculator handles 4-band codes only.
Why do some resistors have Gold or Silver bands?
Gold (×0.1) and Silver (×0.01) are multipliers for very small resistances (used in high-power or precision circuits). Some 5-band resistors also use these for sub-ohm values.
What does ±5% tolerance mean in practice?
A 1 kΩ resistor with ±5% tolerance can be anywhere from 950 Ω to 1050 Ω when manufactured. For most hobby circuits this is fine; precision audio or measurement circuits need ±1% or better.
Do I need an exact tolerance match or can I use a higher value?
For most circuits, a 5% resistor works fine. Use tighter tolerances (1–2%) only if your circuit design requires it (e.g., precision amplifiers, filters). Check your schematic or datasheet.
How do I remember the color sequence?
A mnemonic: 'Black Brown Red Orange Yellow Green Blue Violet Grey White'—or make your own phrase using the first letters (B, BR, R, O, Y, G, B, V, G, W).
What if I can't read the colors at all?
Use a digital multimeter (continuity or resistance mode) to measure the resistor directly—no color decoding needed. Buy a cheap meter if you work with electronics regularly.