What does resistor tolerance tell you?

• A. How much the actual resistance can vary from its nominal value.
• B. The maximum power rating of the resistor.
• C. The temperature coefficient of resistance.
• D. The material of the resistor.

Answer: (A)

Resistor tolerance tells you how much the actual resistance can vary from its stated value. It’s usually shown as a percentage, meaning the real resistance could be that percent above or below the nominal value. For example, a 100 Ω resistor with 5% tolerance could range from 95 Ω to 105 Ω. This matters because real circuits rely on precise values, and tolerances affect current, voltage division, and power calculations. When you stack resistors in series or parallel, these variations can combine in different ways, changing the overall behavior. Tolerance isn’t about how much power the resistor can handle—that’s the power rating. It isn’t about how resistance changes with temperature—that’s the temperature coefficient. And it isn’t about the material itself, though the material influences the nominal value and tolerance characteristics.