Voltage Divider Calculator
Calculate loaded or unloaded resistor-divider output voltage.
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What this tool does
Calculate loaded or unloaded resistor-divider output voltage. Does not model input impedance changing with voltage or component heating.
How to use the Voltage Divider Calculator
- Enter or select input voltage.
- Enter or select upper resistance (ohms).
- Enter or select lower resistance (ohms).
- Enter or select load resistance (ohms, 0 = no load).
- Read the calculated result; change any measurement to compare alternatives.
Formula
Rlower = load>0 ? R2×load/(R2+load) : R2; Vout=Vin×Rlower/(R1+Rlower)
- voltage
- Input voltage
- r1
- Upper resistance (ohms)
- r2
- Lower resistance (ohms)
- load
- Load resistance (ohms, 0 = no load)
Does not model input impedance changing with voltage or component heating.
Worked example
For voltage divider calculator, the following measurements illustrate the exact method: Input voltage: 12; Upper resistance (ohms): 10000; Lower resistance (ohms): 2000; Load resistance (ohms, 0 = no load): 0.
Inputs
- Input voltage12
- Upper resistance (ohms)10000
- Lower resistance (ohms)2000
- Load resistance (ohms, 0 = no load)0
Result
- Output voltage (V)2
Results explained
- Output voltage (V)
- Output voltage (V) from the formula above. Does not model input impedance changing with voltage or component heating.
Frequently asked questions
Rlower = load>0 ? R2×load/(R2+load) : R2; Vout=Vin×Rlower/(R1+Rlower)
Does not model input impedance changing with voltage or component heating.
No. Electrical and HVAC results are estimates. Installation must comply with local codes and be checked by a qualified licensed professional.
Nameplate values, conductor temperature, power factor, efficiency, weather and actual installation conditions may differ from your entered assumptions.
Confirm units, manufacturer data and the formula's assumptions, then verify sizing with the equipment instructions and applicable local standards.