Pick the four band colors on a resistor to decode its resistance — in ohms, kΩ and MΩ, with tolerance.
What Is a Resistor Color Code?
A resistor color code calculator decodes the bands: yellow–violet–red–gold = 47 × 100 = 4,700 Ω = 4.70 kΩ ±5%. The first two bands are digits, the third is the multiplier (power of ten), the fourth is tolerance. Reading direction matters: the tolerance band (gold/silver) sits slightly apart — start from the opposite end.
How to Use
- Pick the band 1 color.
- Pick band 2.
- Pick the multiplier band.
- Pick tolerance.
- Click “Decode Resistor”.
Formula
R = (digit1 × 10 + digit2) × multiplier.
Worked Example
Yellow (4), violet (7), red (×100), gold (±5%): 47 × 100 = 4,700 Ω = 4.70 kΩ ±5%.
How It Works, In Plain Words
The four dropdowns mirror the four printed bands, and the formula does the rest: R = (digit1 × 10 + digit2) × multiplier. Band 1 and band 2 are plain digits — yellow is 4, violet is 7 — so together they form the two-figure number 47. Band 3 is not a third digit; it is a power of ten. Red means ×100, so 47 × 100 = 4,700 Ω. The multiplier list runs from black ×1 up to blue ×1M, with gold ×0.1 and silver ×0.01 at the bottom for values under 100 Ω. Band 4 never changes the headline number: gold there means ±5% tolerance.
The answer is then scaled for readability, as the Benefits list says — Ω → kΩ → MΩ. 4,700 Ω crosses the thousand line, so the tool reports it in kΩ: 4.70 kΩ, with the tolerance alongside. That scaling matters when you compare against a circuit diagram, which may specify the same part either way — the ohms FAQ exists precisely because 4.7 kΩ and 4,700 Ω are the same resistor. And read the tolerance as a range, not a footnote: the mistakes list works it out — a 4.7 kΩ ±5% part can legitimately measure anywhere from 4.465 to 4.935 kΩ.
Real-World Uses
A hobbyist sorting a mixed box of through-hole resistors decodes yellow–violet–red–gold in seconds instead of reaching for a meter: 4.70 kΩ ±5%, filed in the right compartment. A repairer checking a suspect part in a dead amplifier confirms the printed value before blaming it — and knows from the 4.465–4.935 kΩ range whether a meter reading inside it means the part is innocent. A student meeting the code for the first time uses the tool as the answer key while the digit colours — black 0 through white 9, in the order the dropdowns list them — become familiar.
Benefits
- 4-band decoding with tolerance
- Auto scales Ω → kΩ → MΩ
- The reading-direction tip
- Useful for electronics repair and learning
Features of Our Tool
- Instant results in your browser
- No sign-up, no download, 100% free
- Works on mobile, tablet and desktop
- Clear step-by-step explanation below the tool
- Private — your entries never leave your device.
Common Mistakes
- Reading the bands backwards (start opposite the gold/silver band)
- Confusing multiplier with the third digit
- Forgetting tolerance: a 4.7 kΩ ±5% resistor can be 4.465–4.935 kΩ.
Common Mistakes to Avoid
The list covers reading the bands backwards, confusing the multiplier with a third digit, and forgetting tolerance. In prose: learn gold’s double life — in band 4 it is ±5% tolerance, in band 3 it is a ×0.1 multiplier, and the gold-band FAQ spells out both. Do not assume a faded band is the colour it most resembles under warm light; violet (7) and grey (8) sit next to each other in the digit list and one band misread changes the value entirely. And when the decode matters, verify with a meter: the code tells you what the part claims to be, within its ±5%.
FAQ
What is yellow violet red gold?
4.70 kΩ ±5%.
How do I read resistor bands?
First two bands are digits, third is the multiplier, fourth is tolerance — start from the end opposite gold or silver.
What does the gold band mean?
±5% tolerance (or ×0.1 as a multiplier in the third position).
What is 4.7 kΩ in ohms?
4,700 Ω.
What about 5-band resistors?
They add a third digit band — this tool covers the common 4-band type.
Why does the tool show 4.7 kΩ when the example says 4.70 kΩ?
Same value, two trims. The worked example writes 4.70 kΩ ±5%; the tool scales 4,700 Ω into kΩ and formats to at most two decimals, dropping the trailing zero, so it displays 4.7 kΩ. Nothing has changed — 4.7 kΩ, 4.70 kΩ and 4,700 Ω are one resistance, which is why the ohms FAQ gives 4,700 Ω for 4.7 kΩ.
What if my resistor has no fourth band?
Then this decoder needs a small workaround. The tool always asks for a tolerance band, and its list offers brown ±1%, red ±2%, gold ±5% and silver ±10% — a resistor with no tolerance band is a case the page does not cover, so treat any band-4 choice as a placeholder: the resistance from bands 1 to 3 still decodes correctly, but do not rely on the tolerance line.