Resistor Tolerance Calculator Formula
Understand the math behind the resistor tolerance calculator. Each variable explained with a worked example.
Formulas Used
Minimum Resistance
min_r = nominal * (1 - tol_frac)Maximum Resistance
max_r = nominal * (1 + tol_frac)Absolute Variation
variation = nominal * tol_fracVariables
| Variable | Description | Default |
|---|---|---|
nominal | Nominal Resistance(Ω) | 1000 |
tolerance_pct | Tolerance(%) | 5 |
tol_frac | Derived value= tolerance_pct / 100 | calculated |
How It Works
Resistor Tolerance
R_min = R_nom x (1 - tol/100)
R_max = R_nom x (1 + tol/100)
Common: 1% (brown), 5% (gold), 10% (silver).
Worked Example
1k resistor, 5% tolerance.
nominal = 1000tolerance_pct = 5
- 01Variation = 1000 x 0.05 = 50 ohms
- 02Min = 950 ohms, Max = 1050 ohms
Frequently Asked Questions
Which tolerance to choose?
5% for general use, 1% or better for precision circuits.
Temperature effect?
Temperature coefficient (ppm/C) is separate from manufacturing tolerance.
Cost difference?
0.1% resistors cost significantly more than 5% due to extra testing.
Learn More
Guide
Understanding Resistor Color Codes
Learn how to read resistor color codes for 4-band, 5-band, and 6-band resistors. Includes the color chart, tolerance bands, and tips for quick identification.
Ready to run the numbers?
Open Resistor Tolerance Calculator