Resistor Tolerance Calculator Formula

Understand the math behind the resistor tolerance calculator. Each variable explained with a worked example.

Use the Resistor Tolerance Calculator

Formulas Used

Minimum Resistance

min_r = nominal * (1 - tol_frac)

Maximum Resistance

max_r = nominal * (1 + tol_frac)

Absolute Variation

variation = nominal * tol_frac

Variables

VariableDescriptionDefault
nominalNominal Resistance(Ω)1000
tolerance_pctTolerance(%)5
tol_fracDerived value= tolerance_pct / 100calculated

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
  1. 01Variation = 1000 x 0.05 = 50 ohms
  2. 02Min = 950 ohms, Max = 1050 ohms

Ready to run the numbers?

Open Resistor Tolerance Calculator