Resistor Calculator

Use it when your task matches one of these common needs: Decode a common 4-band resistor. See the tolerance range around the nominal resistance. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: The first two bands are digits, the third band is a multiplier, and the fourth band gives tolerance percentage. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

First and second digit bands: the first two significant digits of a common 4-band resistor. Multiplier band: the power-of-ten multiplier that scales the first two digits. Tolerance band: the expected manufacturing range around the nominal resistance.

Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.

Use a multimeter and circuit safety practices for real parts. Color bands can be faded, damaged, or read in the wrong direction. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

Tolerance says how far the real part may be from the printed value. A 1,000 ohm resistor with +/- 5% tolerance may be roughly 950 to 1,050 ohms and still match its rating.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.