Voltage Divider Calculator

Calculate optimal resistor values for voltage division circuits with automatic E-series selection and worst-case tolerance analysis.

Voltage Divider Parameters

Calculate optimal resistor values for a voltage divider circuit. Select E-series and specify constraints to find the best resistor pair.

Input Voltage (V_in)

Target Output Voltage (V_out)

Maximum Total Power Loss

R₁ (Optional - leave empty for auto)

If provided, R₁ is fixed and R₂ will be optimized

R₂ (Optional - leave empty for auto)

If provided, R₂ is fixed and R₁ will be optimized

R₁ Tolerance (%)

R₂ Tolerance (%)

Enabled E-Series (Resistor Standards)

E6(±20% tolerance, 6 values/decade)E12(±10% tolerance, 12 values/decade)E24(±5% tolerance, 24 values/decade)E48(±2% tolerance, 48 values/decade)E96(±1% tolerance, 96 values/decade)

Select which standard resistor series to use for calculation. More series = more options = better accuracy.

Results

Enter parameters to see voltage divider calculation results.

Voltage Divider Formula

A voltage divider is a passive linear circuit that produces an output voltage (V_out) that is a fraction of its input voltage (V_in). The output voltage depends on the ratio of two resistors R₁ (upper) and R₂ (lower). This calculator automatically selects optimal standard resistor values from enabled E-series that meet your power dissipation constraints while minimizing voltage error.

V_{\text{out}} = V_{\text{in}} \cdot \frac{R_2}{R_1 + R_2}

Where:

V_{\text{out}}

= Output voltageV

V_{\text{in}}

= Input voltageV

R_1

= Upper resistorΩ

R_2

= Lower resistorΩ

I

= Divider currentA

P_{\text{total}}

= Total power dissipationW