Resistor calculator
Decode 4-band and 5-band resistor color codes into resistance and tolerance.
What this calculator covers
Use this calculator to turn resistor color bands into a nominal resistance value and a tolerance window.
It is useful when you are reading parts by sight, checking bins, or confirming whether a measured resistance still sits inside the marked tolerance range.
Frequently asked questions
- How do I read resistor color bands?
- Bands are read left to right. On a 4-band resistor, the first two bands give the significant digits, the third band is the multiplier, and the fourth is the tolerance. On a 5-band resistor, the first three bands give significant digits, the fourth is the multiplier, and the fifth is tolerance. The gap before the tolerance band is usually wider to indicate which end to start from.
- What is the difference between a 4-band and 5-band resistor?
- A 4-band resistor encodes a 2-digit significant value, which is sufficient for standard tolerance parts. A 5-band resistor uses three significant digits, providing greater precision for low-tolerance (1% or 0.5%) resistors where the extra digit matters.
- What does the tolerance band mean?
- Tolerance indicates the acceptable range of the actual resistance value relative to the nominal value. A gold band means ±5%, so a 1,000 ohm resistor with gold tolerance can measure anywhere from 950 to 1,050 ohms and still be within spec.
- What does "None" mean for the tolerance band?
- Selecting None corresponds to an unmarked tolerance band, which by convention indicates ±20%. These are typically older or lower-grade components where a wide tolerance is acceptable.
Tool
Run the calculation
Result
RESULT · RESISTOR VALUE
â„–192
Primary result
4.7 k ohms +/- 5%
The 4-band color code resolves to 4.7 k ohms +/- 5%.
- Nominal resistance
- 4.7 k ohms
- Tolerance
- 5%
- Minimum
- 4.465 k ohms
- Maximum
- 4.935 k ohms
Step-by-step solution
- 1.Read the significant digits from the first two bands: 47.
- 2.Apply the multiplier band red = x100 to reach 4.7 k ohms.
- 3.Use the tolerance band gold to build the acceptable range from 4.465 k ohms to 4.935 k ohms.
Walkthrough
Visual walkthrough
Resistor color bands are read left to right: significant digits first, then multiplier, then tolerance.
01
Decode the significant digits
47
Four-band resistors use two significant digits; five-band resistors use three for tighter nominal precision.
02
Apply the multiplier band
47 x 100
The multiplier tells you how many ohms each significant-digit string stands for.
03
Read the tolerance window
Tolerance converts the nominal resistance into the manufacturing range the resistor is allowed to occupy.
4.7 k ohms +/- 5%