Maximum Power Transfer Calculator Formula
Understand the math behind the maximum power transfer calculator. Each variable explained with a worked example.
Formulas Used
Optimal Load Resistance
r_load_optimal = r_thMaximum Power to Load
p_max = pow(v_th, 2) / (4 * r_th)Efficiency at Max Transfer
efficiency = 50Variables
| Variable | Description | Default |
|---|---|---|
v_th | Thevenin Voltage(V) | 10 |
r_th | Thevenin Resistance(Ω) | 50 |
How It Works
Maximum Power Transfer Theorem
Max power is delivered when R_load = R_th.
Formulas
R_load = R_th
P_max = V_th^2 / (4 x R_th)
Efficiency is 50% at this point.
Worked Example
V_th = 10 V, R_th = 50 ohms.
v_th = 10r_th = 50
- 01R_load = R_th = 50 ohms
- 02P_max = 100 / 200 = 0.5 W
- 03Efficiency = 50%
Frequently Asked Questions
Why only 50% efficient?
Equal power is dissipated in source and load when they are matched.
Is max power transfer always desired?
No. Power systems prioritize efficiency. Max power transfer matters in RF and signal work.
AC circuits?
Load impedance should be the complex conjugate of source impedance.
Ready to run the numbers?
Open Maximum Power Transfer Calculator