Free Resistor Color Code Calculator
Pick the color of each band on a 4-band or 5-band resistor and instantly read its resistance in ohms, kilohms, or megohms plus the tolerance and the resulting value range.
Read bands from the end opposite the wider tolerance band. Multiplier gold = ×0.1 and silver = ×0.01 give sub-ohm values; tolerance gold = ±5%, silver = ±10%.
Quick answer
To decode a resistor, read the digit bands as numbers, multiply by the multiplier band, then apply the tolerance band as a ± percentage. For a 4-band resistor the value is (10·D1 + D2) × multiplier; for a 5-band resistor it is (100·D1 + 10·D2 + D3) × multiplier. Example: brown-black-red-gold = 10 × 100 = 1000 Ω = 1 kΩ ±5%.
Formula & method
4-band resistor
R = (10 × D1 + D2) × M, tolerance = ±T%
- D1 — 1st digit (band 1 color value, 0–9)
- D2 — 2nd digit (band 2 color value, 0–9)
- M — multiplier (band 3): black ×1, brown ×10, red ×100, … gold ×0.1, silver ×0.01
- T — tolerance percent (band 4): brown ±1%, red ±2%, gold ±5%, silver ±10%
Color-to-digit map: black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, violet=7, grey=8, white=9. The multiplier color uses the same 0–9 values as powers of ten (e.g. orange = 10³), plus gold = 10⁻¹ and silver = 10⁻².
5-band resistor
R = (100 × D1 + 10 × D2 + D3) × M, tolerance = ±T%
- D1, D2, D3 — three significant digits (bands 1–3)
- M — multiplier (band 4)
- T — tolerance percent (band 5): adds green ±0.5%, blue ±0.25%, violet ±0.1% to the precision range
The 5-band scheme adds a third significant digit for tighter precision parts. The narrow tolerance colors (green ±0.5%, blue ±0.25%, violet ±0.1%) appear mostly on 5-band resistors.
Examples
- Input
- Brown, Black, Red, Gold (4-band)
- Result
- 1 kΩ ±5% (1,000 Ω, range 950 Ω – 1.05 kΩ)
- Why
- Digits brown=1 and black=0 give 10. Multiplier red = ×100, so 10 × 100 = 1000 Ω = 1 kΩ. Tolerance gold = ±5%, giving 1000 × 0.95 = 950 Ω to 1000 × 1.05 = 1050 Ω.
- Input
- Yellow, Violet, Orange, Gold (4-band)
- Result
- 47 kΩ ±5% (47,000 Ω, range 44.65 kΩ – 49.35 kΩ)
- Why
- Digits yellow=4 and violet=7 give 47. Multiplier orange = ×1000, so 47 × 1000 = 47,000 Ω = 47 kΩ. Gold tolerance ±5% gives 47,000 × 0.95 = 44,650 Ω to 47,000 × 1.05 = 49,350 Ω.
- Input
- Brown, Black, Black, Brown, Brown (5-band)
- Result
- 1 kΩ ±1% (1,000 Ω, range 990 Ω – 1.01 kΩ)
- Why
- Three digits brown=1, black=0, black=0 give 100. Multiplier brown = ×10, so 100 × 10 = 1000 Ω = 1 kΩ. Tolerance brown = ±1%, giving 1000 × 0.99 = 990 Ω to 1000 × 1.01 = 1010 Ω.
- Input
- Green, Blue, Gold, Gold (4-band)
- Result
- 5.6 Ω ±5% (range 5.32 Ω – 5.88 Ω)
- Why
- Digits green=5 and blue=6 give 56. The gold multiplier = ×0.1, so 56 × 0.1 = 5.6 Ω. Gold tolerance ±5% gives 5.6 × 0.95 = 5.32 Ω to 5.6 × 1.05 = 5.88 Ω. Gold and silver multipliers are how resistors reach values below 10 Ω.
When to use this tool
- Identifying an unmarked through-hole resistor pulled from a parts bin or salvaged board before placing it in a circuit.
- Checking a resistor you just installed against the schematic value to catch a wrong-part assembly error.
- Learning or teaching the color code for electronics classes, hobby kits, and exam prep without memorizing the full table.
- Decoding precision 5-band resistors where the third digit and tight tolerance (±0.1% to ±1%) matter for the design.
Common mistakes
- Reading the bands backwards. Hold the resistor so the lone tolerance band (usually gold or silver, often slightly separated) is on the right, then read the digit bands from left to right.
- Confusing the gold/silver multiplier with the gold/silver tolerance. On the multiplier band gold means ×0.1 and silver means ×0.01; on the tolerance band gold means ±5% and silver means ±10%.
- Mixing up 4-band and 5-band layouts. A 5-band resistor has three digit bands before the multiplier, so treating it as 4-band shifts every value and gives a wildly wrong answer.
- Assuming the band order black, brown, red… equals 1, 2, 3. Black is 0, not 1, so brown=1 and red=2 — the count starts at zero.
Frequently asked questions
How do I read a 4-band resistor color code?
Orient the resistor with the gold or silver tolerance band on the right. The first two bands are digits (e.g. brown=1, black=0 → 10), the third band is the multiplier (red = ×100), and the fourth is tolerance. So brown-black-red-gold is 10 × 100 = 1000 Ω = 1 kΩ ±5%.
What is the difference between a 4-band and 5-band resistor?
A 4-band resistor uses two significant digits, a multiplier, and a tolerance band. A 5-band resistor adds a third significant digit before the multiplier, giving finer resolution for precision parts. For example, a 5-band code reads three digits then multiplies, while a 4-band reads only two.
What do the gold and silver bands mean?
It depends on the band's position. As a multiplier (the band just before the tolerance), gold means ×0.1 and silver means ×0.01, used for sub-ohm resistors. As the tolerance band (the last band), gold means ±5% and silver means ±10%.
What color is a 10k ohm resistor?
A 10 kΩ ±5% 4-band resistor is brown, black, orange, gold: brown=1 and black=0 give 10, orange = ×1000, so 10 × 1000 = 10,000 Ω = 10 kΩ, with gold = ±5% tolerance.
Which end of the resistor do I start reading from?
Start from the end opposite the tolerance band. The tolerance band is usually gold or silver and is often spaced slightly farther from the others. If both ends look ambiguous, the side that produces a standard E-series value is almost always the correct reading direction.
What does the tolerance percentage actually tell me?
Tolerance is how far the real resistance may stray from its nominal value. A 1000 Ω resistor at ±5% can measure anywhere from 950 Ω to 1050 Ω and still be in spec. Tighter tolerances (±1%, ±0.1%) cost more and are used where the exact value matters, such as analog filters and reference dividers.
Sources & references
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Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.
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