Enter Calculator Values
Example Data Table
| Vin | R1 | R2 | Load | Approximate Purpose |
|---|---|---|---|---|
| 12 V | 10 kΩ | 5 kΩ | 100 kΩ | Sensor input scaling |
| 9 V | 6.8 kΩ | 3.3 kΩ | 47 kΩ | Logic level reduction |
| 24 V | 33 kΩ | 10 kΩ | 220 kΩ | Metering circuit |
Formula Used
Basic output: Vout = Vin × R2 ÷ (R1 + R2)
Loaded lower resistance: Rbottom = (R2 × RL) ÷ (R2 + RL)
Loaded output: Vout loaded = Vin × Rbottom ÷ (R1 + Rbottom)
Divider current: I = Vin ÷ (R1 + R2)
Power: P = I²R or P = V² ÷ R
Thevenin resistance: Rth = (R1 × R2) ÷ (R1 + R2)
How to Use This Calculator
- Select analyze mode to test existing resistor values.
- Select design mode to calculate resistor values from a target output.
- Enter the supply voltage and resistor values.
- Add load resistance when the output feeds another circuit.
- Enter resistor tolerance to estimate worst case output range.
- Press calculate to show results above the form.
- Use CSV or PDF buttons to save your result report.
Voltage Splitter Design Guide
What a Voltage Splitter Does
A voltage splitter uses two resistors to create a lower voltage from a higher supply. It is also called a voltage divider. The output is taken from the junction between the two resistors. This simple circuit is common in measurement, sensing, biasing, reference scaling, and signal conditioning tasks.
Why Load Resistance Matters
A divider formula looks easy when nothing is connected to the output. Real circuits are different. The next stage becomes a load. That load sits in parallel with the lower resistor. It changes the lower effective resistance and pulls the output down. This calculator includes load resistance so the result is more realistic.
Choosing Practical Resistor Values
Very small resistor values waste current and create extra heat. Very large values save current but may become noisy or sensitive to input leakage. For many low power signal circuits, kilo-ohm values are a good starting point. Precision measurement circuits may need tighter tolerance parts and a buffered output.
Power and Safety Checks
Every resistor has a power rating. The calculator estimates power in each resistor and in the load. Select resistors with enough margin above the calculated value. This is important when the divider is connected to higher supply voltages. Heat changes resistance and may affect accuracy.
Tolerance Range
Resistors are not exact. A five percent resistor can be above or below its marked value. The worst case output estimate shows how far the voltage may move when R1 and R2 drift in opposite directions. This helps during design reviews and component selection.
Best Use Cases
A voltage splitter works well for light loads, reference inputs, analog sensing, and high impedance measurement pins. It is not a voltage regulator. Avoid using it to power changing loads. When the load current varies, use a regulator, buffer, or dedicated driver instead.
FAQs
What is a voltage splitter?
A voltage splitter is a two-resistor circuit that creates a lower output voltage from a higher input voltage.
Is a voltage splitter the same as a voltage divider?
Yes. Both names usually describe the same resistor network used to divide an input voltage into a smaller output voltage.
Why does load resistance change the output?
The load sits in parallel with the lower resistor. This reduces effective resistance and usually lowers the output voltage.
Can I use this calculator for sensor circuits?
Yes. It is useful for scaling sensor outputs, checking input limits, and estimating loading effects before building the circuit.
Can a voltage splitter power a device?
It is not recommended for variable loads. Use a regulator or driver when a device needs stable operating power.
What resistor tolerance should I enter?
Use the tolerance printed in the resistor specification, such as 1%, 2%, 5%, or 10%.
Why is power calculation important?
Power shows heating stress. Choose resistor ratings above calculated power to improve reliability and reduce drift.
What is Thevenin resistance?
Thevenin resistance is the divider output resistance seen by the load. Lower values reduce loading error but use more current.