Raspberry Pi Power Calculator

Power supply sizing from Pi model and peripherals.

Input Voltage (V)

R1 - Top Resistor (Ω)

R2 - Bottom Resistor (Ω)

Load Resistance (Ω)

Tab to move between fields

Output Voltage (unloaded, V)

2.5

Output Voltage (loaded, V)

2.5

Divider Ratio0.5

Quiescent Current (mA)0.25

Total Current (mA)0.25

Output Impedance (Ω)5,000

Power Dissipated (mW)1.25

Load Voltage Error (%)0

How to Use This Calculator

Enter your supply voltage and the resistor values R1 (top) and R2 (bottom) in the divider network.
Set the load resistance to model the circuit under load.
Review unloaded and loaded output voltage, divider ratio, and quiescent current (mA).
Check total current draw to ensure your power supply can handle the combined load.

How the result changes with Input Voltage (V)

Input Voltage (V): Source voltage applied to the divider (e.g. 5V, 12V).
R1 - Top Resistor (Ω): Resistance of top resistor (connected to Vin).
R2 - Bottom Resistor (Ω): Resistance of bottom resistor (connected to ground).
Load Resistance (Ω): Resistance of load connected to output (0 = no load / open circuit).

Output Voltage (unloaded, V): Vout = Vin x R2 / (R1 + R2) with no load.
Output Voltage (loaded, V): Output voltage with load resistance in parallel with R2.
Divider Ratio: Fraction of input voltage appearing at output (R2 / (R1+R2)).
Quiescent Current (mA): Current flowing through divider with no load.
Total Current (mA): Total current from supply including load.
Output Impedance (Ω): Thevenin output impedance (R1 || R2). Lower is better for driving loads.
Power Dissipated (mW): Total power wasted as heat in the resistors.
Load Voltage Error (%): Percent deviation from ideal due to load. Keep under 1% for accurate readings.

Identify Input Parameters
4 parameters
Input Voltage (V) = 5, R1 - Top Resistor (Ω) = 10000, R2 - Bottom Resistor (Ω) = 10000, Load Resistance (Ω) = 0 = 4 input(s) provided
Calculate Output Voltage
Output Voltage = inputVoltage * r2 / (r1 + r2)
2.5 = 2.5
Calculate Output Voltage
2.5 = 2.5
Calculate Divider Ratio
Divider Ratio = r2 / (r1 + r2)
0.5 = 0.5
Calculate Quiescent Current
Quiescent Current = (inputVoltage / (r1 + r2)) * 1000
0.25 = 0.25