Set the input
Select the source and type the input voltage.
WAVESPEED AI VOLTAGE DIVIDER CALCULATOR Your circuits stay on your device
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Free Voltage Divider CalculatorChange the resistors, read the output.
A 9 V source across 2 kΩ and 1 kΩ opens with a voltmeter on the output: 3 V, from Vout = Vin × R2 / (R1 + R2).
Type new values for the resistors or the source and the voltmeter, current and power update at once. Add a load to see how it pulls the output down.
Live voltmeterCurrent & power per resistorAdd a load
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THREE SIMPLE STEPS
How to use the Voltage Divider Calculator
Set R1 and R2
Select each resistor and type its value with SI prefixes, such as 4.7k or 10k.
Read the output
The voltmeter shows Vout. Select a resistor to see its current and the power it takes.
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Voltage Divider Calculator FAQ
What is the voltage divider formula?
Vout = Vin × R2 / (R1 + R2), where R2 is the resistor between the output and ground. With 9 V, R1 = 2 kΩ and R2 = 1 kΩ the output is 3 V.
How do I pick the resistors?
Choose the ratio for the output you need, then the size for the current: the divider draws Vin / (R1 + R2). Larger values waste less power; smaller values hold up better under a load.
What happens when I connect a load?
The load sits in parallel with R2, lowering the effective resistance and the output voltage. Add a resistor across R2 in the circuit to see the effect.
Can I use a potentiometer as a divider?
Yes. Add a potentiometer, connect its ends across the source and take the output from the wiper. Move the wiper slider to change the output.
Is it free?
Yes, with no sign-up. Everything is worked out in your browser, and you can save the circuit or share it as a link.
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Live voltmeter · Current & power per resistor · Add a load