⚡ Voltage Divider Calculator

🛡️ 100% Client‑Side — Private
Standard · Reverse · Loaded — E24/E12 · Power Rating
📊 Output Voltage
2.50 V
Current (Total)
0.25 mA
R1 Power
0.63 mW
R2 Power
0.63 mW
Rec. Rating
1/8 W
R1 standard: 10kΩ R2 standard: 10kΩ
R1
R2
✓ Real‑time · Standard E24/E12 values · Power‑aware

📘 Voltage Divider Guide

A voltage divider uses two resistors to scale down an input voltage. The output voltage is given by Vout = Vin × R2 / (R1 + R2). When a load is connected across R2, the effective resistance decreases, causing Vout to drop — this is the loading effect.

❓ FAQ

Why does Vout drop under load?

The load resistor RL is in parallel with R2, reducing the effective lower resistance. The formula becomes Vout = Vin × (R2‖RL) / (R1 + R2‖RL). To minimize loading, use a load resistance much larger than R2 (e.g., RL > 10×R2).

How are standard resistor values chosen?

We match the calculated resistance to the nearest value in the E24 (5%) or E12 (10%) series. The tool displays both the theoretical and standard values.

What power rating do I need?

Calculate power using P = I²R. Choose a resistor with a power rating at least 2× the calculated value for safety. The tool recommends a minimum rating.