Free Resistor Calculator - Electronics Made Easy
Calculate resistor values from color codes, series/parallel combinations, and power ratings. Essential for electronics projects and circuit design.
Quick Answer
Series: add resistances (100+100+100=300Ω). Parallel: use 1/R_total = 1/R1 + 1/R2 (two 100Ω parallel = 50Ω). Color codes: bands indicate value.
Key Facts about Resistor Calculator:
- Series: R_total = R1 + R2 + R3...
- Parallel: 1/R = 1/R1 + 1/R2...
- Two equal parallel R = R/2
- Colors: Black=0, Brown=1, Red=2...
- Gold tolerance = ±5%, Silver = ±10%
Why Use Our Resistor Calculator?
Complete resistor calculations:
Color Codes
Decode resistor bands.
Series
Add resistors in series.
Parallel
Calculate parallel resistance.
Power Rating
Check power dissipation.
Instant Results
Get values immediately.
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How to Resistor Calculator in 3 Easy Steps
Calculate resistors:
Enter Values
Colors or resistance values.
Choose Mode
Color decode, series, parallel.
Get Result
See calculated resistance.
Electronics Made Easy
Decode any color code
Series calculations
Parallel calculations
Power ratings
Common Use Cases for Resistor Calculator
Perfect for:
Frequently Asked Questions
Everything you need to know about our resistor calculator
How do I read resistor color codes?
Band 1-2: digits, Band 3: multiplier, Band 4: tolerance
For 4-band resistors: first two bands are digits, third is multiplier, fourth is tolerance. Brown-Black-Red-Gold = 10 × 100 = 1000Ω (1kΩ) ±5%.
How do I calculate series resistance?
Add them: R_total = R1 + R2 + R3...
Add all resistances together. R_total = R1 + R2 + R3... Three 100Ω resistors in series = 300Ω total.
How do I calculate parallel resistance?
1/R_total = 1/R1 + 1/R2... (parallel is always less)
1/R_total = 1/R1 + 1/R2 + 1/R3... Two 100Ω resistors in parallel: 1/R = 1/100 + 1/100 = 2/100, so R = 50Ω.
Still have questions? Try the tool yourself!
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