Resistance calculator

Electricity
86 calculations
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📝 How it works:
Calculates total resistance for series and parallel connection of up to 3 resistors

Fill in the fields below and click "Calculate".

Resistor calculator for series and parallel connection

Resistors must be combined for complex circuits. Our calculator determines the total resistance for:

  • Series circuit: R_ges = R1 + R2 + R3 (resistors add up)
  • Parallel connection: 1/R_ges = 1/R1 + 1/R2 + 1/R3
  • LED series resistors: Several LEDs in series or parallel
  • Voltage divider: Generate partial voltages for sensors
  • Measuring bridges: Dimensioning Wheatstone bridges

Row connection: Resistors are simply added together. 3× 100Ω in series = 300Ω. The current is the same everywhere, voltages add up.

Parallel circuit: Total resistance is less than the smallest individual resistance. 2× 100Ω in parallel = 50Ω. Voltages are equal, currents add up.

Special case 2 equal resistors in parallel: R_ges = R / 2. Three equal resistors: R_ges = R / 3.

Practical tip: By combining the E12 standard series (10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 Ω), you can generate almost any required resistor value. Example: 22Ω + 33Ω = 55Ω (series). 100Ω || 100Ω = 50Ω (parallel).

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