Electrical Fundamentals
Loaded Voltage Divider Calculator
The purpose of Loaded Voltage Divider is to turn source voltage, upper resistance, lower resistance, and load resistance into loaded output voltage. Keep the source condition with the saved result so later comparisons remain meaningful.
Run the Loaded Voltage Divider scenario
Replace the examples with values from the same case.
Formula used on this page
For this worksheet, the governing relationship is Vout = Vin × (Rbottom || Rload) ÷ (Rtop + Rbottom || Rload). The entered quantities are Source voltage, Upper resistance, Lower resistance, and Load resistance.
Using the loaded examples gives 3.31 V. Your saved case should identify where each entry came from.
Calculate loaded output voltage from source voltage, upper resistance, lower resistance, and load resistance. Use Voltage Divider Calculator as the companion source for output voltage.
Input notes
Use readings taken at the same circuit state and reference node. A source note beside each entry makes the result reproducible.
A denominator entry cannot be zero. Confirm decimal placement whenever a source uses a different unit scale. A separate internal resistance result is available from Battery Internal Resistance Calculator.
- Source voltage
- Default example: 12 V. Enter source voltage in V.
- Upper resistance
- Default example: 10000 Ω. Enter upper resistance in Ω.
- Lower resistance
- Default example: 4700 Ω. Enter lower resistance in Ω.
- Load resistance
- Default example: 20000 Ω. Enter load resistance in Ω.
Interpreting the answer
The calculated Loaded output voltage is meaningful only with its input conditions attached. Compare it with the expected circuit operating point.
Keep the input set beside the output so another reader can reproduce it. A connected part of the work can be checked with Current Divider Calculator.
Where this estimate can fail
The load is treated as a fixed resistance across the lower divider resistor.
The arithmetic intentionally leaves out instrument loading, transient behavior, and component tolerance. Do not hide omitted behavior inside an unexplained correction factor.
Keep source conditions with each voltage, current, resistance, or charge value.
A second scenario
Change Source voltage from 12 V to 14.399999999999999 V without altering the remaining fields. The calculated value shifts from 3.31 V to 3.97 V.
The comparison demonstrates sensitivity, not a guaranteed field response.
Documenting the calculation
Document source voltage, upper resistance, lower resistance, and load resistance with loaded output voltage. Keep enough context to reproduce the result later.
Transfer loaded output voltage unchanged when passing it to the next worksheet. Apply standard sizes only after all checks are complete.
Common questions before using the result
What happens when a denominator is zero?
Use a measured positive value for Upper resistance, Lower resistance, and Load resistance; zero cannot stand in for missing data.
Should I use measured or nameplate values?
Choose entries that describe the same case. Record conductor temperature and whether values are measured, nominal, or calculated.
What is not captured by this equation?
The load is treated as a fixed resistance across the lower divider resistor. Also consider instrument loading, transient behavior, and component tolerance.
Why might measured loaded output voltage differ?
Recheck units and operating state before investigating instrument loading, transient behavior, and component tolerance.