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_th

Maximum Power to Load

p_max = pow(v_th, 2) / (4 * r_th)

Efficiency at Max Transfer

efficiency = 50

Variables

VariableDescriptionDefault
v_thThevenin Voltage(V)10
r_thThevenin 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
  1. 01R_load = R_th = 50 ohms
  2. 02P_max = 100 / 200 = 0.5 W
  3. 03Efficiency = 50%