03 // Bidirectional STEM Calculators // ENGINEERINGV_out = V_in × (R₂ / (R₁ + R₂))

Resistive Voltage Divider Calculator

A resistive voltage divider scales an input voltage V_in down to a precise reference voltage V_out according to the ratio of bottom resistance R₂ to total series resistance (R₁ + R₂).

V_out = V_in × (R₂ / (R₁ + R₂))

Pick which value you want to calculate (or type into any field):Solving for: V_out — Output Tap Voltage

Output Tap VoltageCalculated

Divided node voltage across R₂ in Volts

0.011,000.00

Input Supply Voltage

Source rail voltage across the series string in Volts

0.11,000.00

Top Resistor (High-Side)

Resistance between V_in and V_out in Ohms

110,000,000.00

Bottom Resistor (Low-Side)

Resistance between V_out and Ground in Ohms

110,000,000.00

Calculated Result · Output Tap Voltage (V_out)

3.3V

Converted units:

Step-by-Step Calculation

01Canonical Law: V_out = V_in × (R₂ / (R₁ + R₂))

02Given Inputs (Base Units): V_in = 5 V, R₁ = 5,151.52 Ω, R₂ = 10,000 Ω

03Solve for V_out (Output Tap Voltage): V_out = 3.3 V

A resistive voltage divider scales an input voltage V_in down to a precise reference voltage V_out according to the ratio of bottom resistance R₂ to total series resistance (R₁ + R₂).

Real-World Reference Values

5V to 3.3V Logic Level ShiftR₁ = 5.1 kΩ, R₂ = 10 kΩ → 3.31V

Standard E24 resistor pair for ADC input scaling

12V Battery Sense to 3.3V ADCR₁ = 27 kΩ, R₂ = 10 kΩ → 3.24V

Draws only 0.32 mA quiescent current

Stiff Divider Rule (10× Rule)R_load ≥ 10 × R₂

Keeps loading error below 10% without op-amp buffer

20-Row Comparison Table

Output Tap Voltage (V_out) · Input Supply Voltage (V_in)

Compare across:

Resistive Voltage Divider Calculator — Input Supply Voltage → Output Tap Voltage
#	Input Supply Voltage (V)	Output Tap Voltage (V)	Δ %
01	0.1 V	0.066 V	-98.00%
02	5 VCurrent	3.3 V	0.00%
03	15.088 V	9.9581 V	+201.76%
04	22.582 V	14.9041 V	+351.64%
05	30.0761 V	19.8502 V	+501.52%
06	37.5701 V	24.7962 V	+651.40%
07	45.0641 V	29.7423 V	+801.28%
08	52.5581 V	34.6883 V	+951.16%
09	60.0521 V	39.6344 V	+1101.04%
10	67.5461 V	44.5804 V	+1250.92%
11	75.0401 V	49.5265 V	+1400.80%
12	82.5341 V	54.4725 V	+1550.68%
13	90.0282 V	59.4186 V	+1700.56%
14	97.5222 V	64.3646 V	+1850.44%
15	105.0162 V	69.3107 V	+2000.32%
16	112.5102 V	74.2567 V	+2150.20%
17	120.0042 V	79.2028 V	+2300.08%
18	127.4982 V	84.1488 V	+2449.96%
19	134.9922 V	89.0949 V	+2599.84%
20	142.4863 V	94.0409 V	+2749.73%

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Frequently Asked Questions

How do I find the exact resistor R₁ needed when R₂ is fixed at 10 kΩ?+

Click SOLVE FOR on R₁, set R₂ = 10 kΩ, and enter your input voltage V_in and target output voltage V_out.

Why shouldn't a resistive voltage divider power a heavy load?+

Any load resistance R_L connected across V_out acts in parallel with R₂, pulling the output voltage down whenever load current rises.

What is the Thévenin equivalent resistance of a voltage divider?+

Looking into the V_out node, the Thévenin source impedance equals R₁ || R₂ = (R₁ × R₂) / (R₁ + R₂).