The Resistor Color Code Calculator helps you determine resistance values from color codes or vice versa.
Supports 4-band and 5-band resistors. The first mode converts color bands to resistance values (ohm/kilohm/megohm) with tolerance and min-max range. The second mode finds the color code from a resistance value. Includes a resistor visualization and a complete color code reference table.
Calculator information
📋 How to use this calculator
- Choose the number of bands: 4-band (standard resistor) or 5-band (precision resistor).
- Pick a color for each band in order from left (nearest the end) to right: digit 1, digit 2, (digit 3 for 5-band), multiplier, and tolerance.
- For reverse mode: enter the desired resistance value (Ω, kΩ, or MΩ) and tolerance, and the calculator will show the color combination.
- Click Calculate to see the resistance value, min-max range based on tolerance, and a color visualization of the resistor.
- Double-check with a multimeter before placing the part in a circuit, especially for precision resistors.
- For series-parallel combinations, compute manually: series R_total = R1 + R2; parallel 1/R_total = 1/R1 + 1/R2.
🧮 Resistor Color Code Reading
4-band: R = (D1 x 10 + D2) x 10^M +/- T%; 5-band: R = (D1 x 100 + D2 x 10 + D3) x 10^M +/- T%
- D1, D2, D3 = significant digits (bands 1, 2, 3)
- M = multiplier (multiplier band), 10^M
- T = tolerance in % (final band)
- Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9
- Gold multiplier = 10^-1 (x0.1); Silver multiplier = 10^-2 (x0.01)
- Tolerance: Brown=+/-1%, Red=+/-2%, Gold=+/-5%, Silver=+/-10%, no band=+/-20%
The color standard follows IEC 60062. Precision 5-band resistors are typically +/-1% or +/-2%.
💡 Worked example: Reading a 4-band resistor: Brown - Black - Red - Gold
Given:- Band 1 (digit 1) = Brown -> 1
- Band 2 (digit 2) = Black -> 0
- Band 3 (multiplier) = Red -> 10^2
- Band 4 (tolerance) = Gold -> +/-5%
Steps:- Combine digits: D1 D2 = 10
- Multiply by the multiplier: 10 x 10^2 = 1,000 Ω
- Convert: 1,000 Ω = 1 kΩ
- Compute tolerance: 1,000 x 5% = 50 Ω
- Value range: 1,000 - 50 = 950 Ω, 1,000 + 50 = 1,050 Ω
Result: 1 kΩ +/- 5% resistor, range 950 - 1,050 Ω. This is one of the most common resistor values in hobby electronics (Arduino, LED current limiting, etc.).
❓ Frequently asked questions
How do I tell the first band from the last band?
The first band is usually closer to one end of the resistor (the gap on the other end is larger). The tolerance band (gold/silver) is always last and never appears as the first band. If both ends look symmetric, rotate the resistor so the gold/silver band is on the right. On 5-band parts, the last band typically sits slightly farther from the other four.
What is the difference between 4-band, 5-band, and 6-band resistors?
4-band: 2 digits + multiplier + tolerance (typical carbon-film resistors). 5-band: 3 digits + multiplier + tolerance (high-precision parts such as metal-film, usually +/-1% or +/-2%). 6-band: 3 digits + multiplier + tolerance + temperature coefficient (TCR) - used for industrial/military precision applications. TCR is color-coded: brown (100 ppm/°C), red (50 ppm/°C), etc.
How do I calculate series and parallel resistors?
Series (end-to-end connection): R_total = R1 + R2 + R3 + ... (always larger than the largest value). Parallel (terminals tied together): 1/R_total = 1/R1 + 1/R2 + 1/R3 + ... or for two resistors: R_total = (R1 x R2) / (R1 + R2). The parallel result is always smaller than the smallest resistor. Combinations are often used to obtain non-standard values.
How do I choose the right resistor wattage?
Calculate the dissipated power: P = I^2 x R = V^2/R. Pick a resistor rated for at least 2x the calculated power (safety margin). 1/4 W resistors handle low current (< 32 mA on 1 kΩ); 1/2 W for moderate current; 1 W and up for higher current. For an LED current limiter on a 5V supply at 20 mA, a 1/4 W resistor is sufficient. Physically larger resistors generally carry higher wattage ratings.
What is the E-series for resistors?
The E-series is the IEC 60063 standard value series: E12 (12 values per decade, 10% tolerance), E24 (24 values, 5%), E48 (48 values, 2%), E96 (96 values, 1%), E192 (192 values, 0.5%). Example E24: 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, etc. The values are distributed logarithmically. Because of this, not every value (e.g., 1.234 kΩ) is stocked - you have to combine parts in series/parallel.
📚 Sources & references
Last updated: May 11, 2026