Divider formula tool
Voltage Divider Output Calculator
Calculate Vout for a two-resistor divider and document the ratio assumptions with circuit notes.
Calculate Voltage Divider Output
Enter input voltage and two resistor values to calculate the unloaded divider output voltage.
Result
Output voltage
8 V
Result notes. Keep inputs, assumptions, and result together before using this value in project records.
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Formula and field context
Calculate Vout for a two-resistor divider and document the ratio assumptions with circuit notes.
Formula context
Voltage Divider Ratio Chart
A two-resistor divider gives Vout = Vin x R2 / (R1 + R2): 24 V to 10 V uses 14 kOhm and 10 kOhm, while 5 V to 3.3 V uses 5.1 kOhm and 10 kOhm. That calculator result is only a starting point: a meter input, PLC analog input, sensor input, or downstream circuit can sit in parallel with R2 and pull the output lower. Use this chart to choose the ratio, check divider current, and decide whether a buffer, different resistor values, or a real regulator is needed.
Formula
Vout = Vin x R2 / (R1 + R2). Divider current = Vin / (R1 + R2).Variables to keep with the result
- Vin is the input voltage across the complete divider.
- R1 is the upper resistor from Vin to the output node.
- R2 is the lower resistor from the output node to the reference side.
- Vout is measured across R2 before any connected load changes the effective lower resistance.
Formula and variables
For a basic two-resistor divider, Vout = Vin x R2 / (R1 + R2). R1 is the upper resistor from the input source to the output node, and R2 is the lower resistor from the output node to the reference point. The result assumes an unloaded divider, which means the connected load does not significantly change the effective lower resistance.
U.S. field context and example
Voltage dividers show up in control panels, sensing circuits, electronics troubleshooting, analog inputs, and low-voltage signal conditioning. For example, a 24 V source with R1 = 10,000 ohms and R2 = 5,000 ohms gives Vout = 24 x 5,000 / 15,000, or 8 V before load effects. Keep the source voltage, resistor tolerance, and whether a load is attached with the worksheet result.
Assumptions and limits
This tool does not model loading, resistor wattage, source impedance, noise, insulation rating, or safety isolation. If the divider feeds an analog input, meter, relay module, or controller input, check the input impedance and power dissipation. Use the full voltage divider or circuit-analysis calculator when load current, tolerance stack-up, or a target output design must be reviewed.
Common mistakes
Common mistakes include swapping R1 and R2, assuming the divider can supply real load current, ignoring resistor power dissipation, and using a divider where isolation or a listed control transformer is required. The formula is useful for signal-level work, but it is not a substitute for equipment instructions or safe control-circuit design.