Decode any resistor in both directions: pick the band colors and read the value, tolerance range, and temperature coefficient — or type a resistance and get the band colors back, with the nearest E24 and E96 standard values you can actually order. The live SVG mirrors your selection, so it doubles as a teaching aid for reading real parts.
Everything runs in your browser. When the resistor is decoded, the Ohm's law calculator turns it into currents and power figures, the unit converter handles the adjacent physical conversions, and the percentage calculator is handy for tolerance math.
Frequently asked questions
How do I read a 4-band resistor?
The first two bands are digits, the third is the multiplier, and the fourth is the tolerance. Brown-black-red-gold reads 1, 0, ×100 = 1,000 Ω (1 kΩ) at ±5%. Hold the resistor with the tolerance band (usually gold or silver, and set slightly apart) on the right.
What is the difference between 4-, 5-, and 6-band resistors?
Five-band resistors add a third digit for precision parts (typically ±1% or better). Six-band resistors add a temperature coefficient band in ppm/K, showing how much the resistance drifts as the part heats up. The reading rule is the same — digits, multiplier, tolerance, then tempco.
Which end do I start reading from?
Start from the band closest to a lead edge; the tolerance band is usually spaced slightly apart and is gold or silver on common parts — those two colors can never be a first digit, which is the quickest sanity check. If a reading gives a nonsense value like 0.1 Ω for a big part, try it the other way round.
What are E24 and E96 standard values?
Manufacturers only make resistors in standard steps: E24 has 24 values per decade (the familiar 1.0, 2.2, 4.7 series at ±5%), E96 has 96 (for ±1% parts). When you enter an arbitrary value, the tool shows the nearest value in each series — the part you can actually buy.
Why does a value like 1,234 Ω not produce bands?
Color bands can only carry two significant digits on a 4-band part and three on a 5- or 6-band part, so 1,234 Ω has no exact code. Rather than quietly rounding it, the tool says so and offers the nearest E24 and E96 values — click one to snap the input to a resistor that actually exists.