Calculator tool
How this calculator works
Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.
How the 4-Band Code Works
A 4-band resistor uses:
- the first band for the first digit,
- the second band for the second digit,
- the third band for the multiplier,
- the fourth band for tolerance.
For example, brown-black-orange-gold means 10 x 10^3 ohms, or 10 kΩ, with ±5% tolerance.
Why Tolerance Matters
The printed value is a target, not an exact promise. A 10 kΩ ±5% resistor can still be within specification from 9.5 kΩ to 10.5 kΩ.
How to Use the Result
Use the color bands to identify the part, then use a meter when the exact resistance matters. Old components, poor lighting, and unclear orientation can make colors harder to read correctly.
Frequently asked questions
Which band should I read first?
Start from the side where the bands are grouped more closely. The tolerance band is usually spaced farther away at the end.
What does the multiplier band do?
It multiplies the first two digits by a power of ten. Orange, for example, represents a multiplier of .
Why is the actual resistance a range?
Because manufacturing tolerance allows the real part to vary around the printed value and still be considered acceptable.
Should I still use a multimeter?
Yes, whenever the exact value affects the circuit. The color code identifies the part class; a meter checks the actual component in hand.
