How do you calculate series resistance?

Series: R_total = R1 + R2 + R3 + ... Simply add all resistor values together.

How do you calculate parallel resistance?

Parallel: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ... The total is always less than the smallest resistor.

Two equal resistors in parallel give exactly half the value. Two 100Ω resistors in parallel = 50Ω.

For series connections, resistances add directly: R_total = R1 + R2 + ... + Rn.

For parallel connections, the reciprocals add: 1/R_total = 1/R1 + 1/R2 + ... The total is always less than the smallest resistor.

Each parallel path provides an additional route for current, reducing overall opposition to flow.

Result is exactly half. Two 100Ω → 50Ω.

Solve parallel groups first, then add series portions. Use this calculator for each sub-group.