4-band: digit1·digit2 × multiplier ± tolerance. 5-band adds a third significant digit for precision resistors. Related: Ohm's law, electricity cost.
You select color bands for each position on the resistor. For a 4-band resistor, the first two bands form a two-digit number, the third band is the multiplier, and the fourth is the tolerance. A 5-band resistor adds a third significant digit for precision. The tool multiplies the base digit value by the multiplier to get nominal resistance, then applies the tolerance percentage to show the min/max range.
Start reading from the end where the bands are grouped closest together. The tolerance band (gold or silver) is usually spaced slightly further from the others and marks the far end.
A 4-band resistor has two significant digits, giving values like 47 kΩ or 10 kΩ. A 5-band resistor adds a third digit for finer precision, allowing values like 475 kΩ or 100 kΩ. Precision and metal-film resistors typically use 5 bands.
If the measured value falls outside the tolerance range, the resistor may be damaged, overheated, or aged. Replace it with a fresh component and verify your multimeter calibration.
No — surface-mount (SMD) resistors use a numeric code printed on the component rather than color bands. Look for a 3-digit or 4-digit code and use an SMD resistor code chart instead.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.