Carbon film or metal film resistor?

Carbon film vs metal film resistors: tolerance, colour bands, temperature coefficient, noise, cost, which one goes where, and common mistakes.

Short answer

Carbon film is fine for LEDs, pull-ups and general circuits. Use metal film for measurement, audio, op-amp feedback and precision dividers; the price gap is now so small that many designers use metal film everywhere.

Comparison

	Carbon film	Metal film
Tolerance	Usually 5%	1% (or even 0.1%)
Colour bands	Usually 4 bands	Usually 5 bands
Body colour	Mostly beige / light brown	Mostly blue
Change with temperature	High (hundreds of ppm/°C)	Low (≈50–100 ppm/°C)
Noise	Higher	Lower
Cost	Cheapest	Slightly more
Typical use	LED current resistor, pull-up, general circuits	Measurement, audio, op-amp feedback, reference dividers

Carbon film is enough if…

✓It's somewhere precision doesn't matter, like an LED or pull-up
✓A 5% error doesn't affect the circuit
✓You need lots of cheap resistors

Choose metal film if…

✓It's a voltage-measuring divider or sensor circuit
✓Noise matters in an audio or op-amp circuit
✓The value must stay put as the temperature changes

Common mistakes

!Reading the colour code from the wrong end. The tolerance band is usually set slightly apart; start reading from the other end.
!Using a 1/4 W resistor without working out the power. Calculate P = I² × R and choose at least twice that rating.
!Using 5% resistors in a precision divider and being surprised the reading drifts.
!Assuming every blue resistor is 1%. Read the tolerance from the last band (brown 1%, gold 5%).
!Measuring a resistor in circuit without accounting for parallel paths. Lift one leg of a suspect resistor before measuring.

🔒 This content is in the repair pack

The repair pack unlocks all interactive content in one go: diagrams and current flows, the Repair Workshop, simulations, concepts, IC guides, the Component Library and comparison guides. One sample in every section is free.

Repair pack: 5,000 ₺, members get 10% off → 4,500 ₺. Or 1-week access for 1,000 ₺.

Learn the topic in depth

More guides

MOSFET or BJT?Zener or regular diode?Electrolytic, ceramic or tantalum?Triac or thyristor (SCR)?MOSFET or IGBT?