Electronics

Voltage Divider Calculator

Design resistor divider networks with confidence. The calculator accounts for load resistance and shows tap voltage and current draw.

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Voltage Divider

Design resistor dividers with load-aware output voltage.

Input voltage (V)R1 (Ω)R2 (Ω)Load (Ω, optional)

Output voltage

3.3275 V

Divider current

1.845 mA

Load current

0.333 mA

R1 power

0.016 W

R2 power

0.007 W

Divider formula

Vout = Vin × (R₂ / (R₁ + R₂))

If a load is attached, the effective lower resistance becomes (R₂ × R_load) ÷ (R₂ + R_load), which the calculator applies automatically.

Enter the supply voltage and resistor values.
Add an optional load resistance to see how it drags down the divider output.
Review the output voltage, current through the chain, and power for each resistor.

Example

Input: Vin = 12 V, R1 = 4.7 kΩ, R2 = 2.2 kΩ, Load = 10 kΩ

Output: Vout ≈ 3.08 V, Chain current ≈ 1.76 mA

How do I pick resistor ratios?

Use the target Vout to back into resistor ratios, then round to the nearest standard E-series values when selecting parts.

Does it support potentiometers?

Treat the pot as R1 + R2 segments. Adjust each segment to model different wiper positions.