Enter Divider Inputs
For AC signals, use RMS values when you want RMS-based current and power results.
Example Data Table
| Input Voltage | Rs | R1 | R2 | RL | Tolerance | Loaded Output | Unloaded Output | Attenuation |
|---|---|---|---|---|---|---|---|---|
| 12 V | 50 Ω | 1000 Ω | 2200 Ω | 10000 Ω | 1 % | 7.584 V | 8.123 V | -3.985 dB |
| 5 V | 0 Ω | 4700 Ω | 10000 Ω | 47000 Ω | 5 % | 3.204 V | 3.401 V | -3.864 dB |
Formula Used
Vout(unloaded) = Vin × R2 / (Rs + R1 + R2)
Rlower = R2 || RL = 1 / (1/R2 + 1/RL)
Vout(loaded) = Vin × Rlower / (Rs + R1 + Rlower)
Itotal = Vin / (Rs + R1 + Rlower)
Attenuation(dB) = 20 × log10(Vout / Vin)
Rth = (Rs + R1) || R2
How to Use This Calculator
- Enter the source voltage driving the divider.
- Add any source resistance from the signal source or previous stage.
- Enter the upper resistor as R1 and the lower resistor as R2.
- Provide a load resistance if the divider feeds another circuit.
- Set resistor tolerance to estimate a possible output range.
- Press Calculate Divider to show results above the form.
- Review the voltage graph, current, attenuation, and power values.
- Use the CSV or PDF buttons to export the calculated report.
Frequently Asked Questions
1) Why does the loaded output voltage drop?
A load placed across the lower resistor reduces the effective lower resistance. That changes the divider ratio and usually lowers the output voltage compared with the unloaded value.
2) When should I enter source resistance?
Enter source resistance when the signal source is not ideal. Many sensors, filters, and instrument outputs have finite impedance that affects the final divider voltage.
3) What does attenuation in dB mean here?
It shows how much the divider reduces signal amplitude. A more negative number means stronger reduction. This is useful when matching levels between stages.
4) Can I use this for AC signals?
Yes, for resistive dividers. Use RMS voltage values if you want RMS current and power. Reactive components and frequency effects are not modeled here.
5) Why is the Thevenin resistance useful?
Thevenin resistance tells you how strongly the divider can drive the next stage. Lower Thevenin resistance usually means less sensitivity to load changes.
6) What does the tolerance window show?
It estimates the possible loaded output range when resistor values vary by the specified tolerance. This helps you judge worst-case signal accuracy.
7) Should I worry about resistor power dissipation?
Yes, especially with low resistor values or higher input voltage. Always choose resistor power ratings comfortably above the calculated dissipation.
8) How do I choose good resistor values?
Balance target output voltage, load sensitivity, current draw, noise, and power loss. Lower values drive loads better, while higher values reduce wasted current.