Physics
Resistors in parallel
Parallel conductances add, so the reciprocals of the resistances sum.
The Formula
1/R = 1/R1 + 1/R2 + 1/R3
Parallel conductances add, so the reciprocals of the resistances sum.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| R | Total resistance | ohms | The equivalent resistance, in ohms. |
| R1, R2, R3 | Individual resistances | ohms | Each parallel branch, in ohms. |
What Each Symbol Means
Rohms
Total resistance
The equivalent resistance, in ohms.
R1, R2, R3ohms
Individual resistances
Each parallel branch, in ohms.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate total resistance page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Total Resistance, filed under Science. Every number the guide produces comes from substituting into this one line.