Resistor Color Code Calculator
Decode 3, 4, 5 and 6-band resistors, convert a value back into colours, and read SMD markings including EIA-96.
Value to colours
Surface-mount markings
Reading them in practice
- Which end is first? The tolerance band is usually gold or silver and usually has a wider gap before it. If both ends look the same, read it both ways — one direction normally gives a standard value and the other does not.
- Check against the preferred series. Resistors are made in E12 and E24 values, so a reading of 3.9 kΩ is plausible and 3.7 kΩ almost certainly means you read a band wrong. This tool says which series a value belongs to for exactly that reason.
- Colours lie under warm light. Brown, red and orange are genuinely hard to separate on a small part, and so are brown and violet. Daylight or a white LED helps more than squinting does.
- When in doubt, measure it. A multimeter settles in two seconds what the bands argue about, and it also catches the resistor that has drifted or been cooked.
How to use
- Pick the number of bands your resistor has.
- Set each band colour — the drawing updates as you go.
- Read the value, tolerance and whether it is a standard series value.
- Or work backwards from a value, or type an SMD marking.
Frequently asked questions
Which end do I read from?
The tolerance band is usually gold or silver and normally sits after a wider gap. Where both ends look alike, read it both ways — one direction almost always gives a standard E12 or E24 value and the other does not, which settles it.
What does the preferred series tell me?
Resistors are manufactured in defined value sets, mostly E12 and E24. So 3.9 kΩ is a real part and 3.7 kΩ almost certainly means a band was misread. This tool reports which series a decoded value belongs to precisely so a misreading announces itself.
What is the fifth and sixth band for?
A fifth band adds a third significant digit, which is how precision resistors express values like 4.99 kΩ. A sixth adds the temperature coefficient in parts per million per kelvin — how much the value drifts as the part heats, which matters in precision analogue work and almost nowhere else.
Why does it refuse some combinations?
Because a real resistor cannot carry them. Gold is a multiplier and a tolerance, never a digit; orange is a digit and a multiplier, never a tolerance. A decoder that quietly accepts those will confidently report a value for a part that does not exist, which is worse than saying no.
How do I read surface-mount resistors?
Three and four-digit codes are significant figures followed by a power of ten, so 103 is 10 kΩ and 1002 is also 10 kΩ. An R marks a decimal point: 4R7 is 4.7 Ω. EIA-96 uses a two-digit lookup plus a letter multiplier and is genuinely unreadable without the table, which is why it is built in here.
Why are the colours so hard to tell apart?
Because brown, red and orange are close under warm light, and so are brown and violet on a small part with a dark body. Daylight or a white LED helps far more than squinting. Where it matters, a multimeter settles in two seconds what the bands argue about.
What does tolerance actually mean in practice?
The range the manufacturer guarantees. A 5% 1 kΩ part is somewhere between 950 and 1,050 Ω, and it will not drift outside that in normal use. For most circuits this is irrelevant; for a divider setting a reference or a filter corner it is the thing that decides whether the design works.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.