Question 1

How do I read resistor color codes?

Accepted Answer

Use the band colors: first two bands are digits, the third is multiplier, and the fourth (or fifth) is tolerance.

Question 2

What wattage do I need?

Accepted Answer

Estimate power with P = I^2*R or P = V^2/R and choose a resistor rated at least 2x the expected dissipation.

Question 3

Series vs parallel?

Accepted Answer

Series adds resistances; parallel uses reciprocals. Use parallel to achieve non-standard values.

Question 4

What tolerance should I pick?

Accepted Answer

1% (brown) for precision, 5% (gold) for general purpose; tighter tolerances cost more.

Question 5

Does temperature coefficient matter?

Accepted Answer

For precision circuits, lower ppm/C improves stability as temperature changes.

Resistor Calculator — Color Code & Resistance Calculator