Voltage divider equations
An unloaded divider uses two series resistors. A connected load appears in parallel with the lower resistor.
Vout = Vin × R2 / (R1 + R2)Rlower = R2 ∥ RL = R2 × RL / (R2 + RL)Vout,loaded = Vin × Rlower / (R1 + Rlower)P = I²Rwhere:
- Vin
- Divider input voltage[V]
- Vout
- Divider output voltage[V]
- R1
- Upper resistor[Ω]
- R2
- Lower resistor[Ω]
- RL
- Connected load resistance[Ω]
- Rlower
- Effective loaded lower resistance[Ω]
A voltage divider is suitable for signal scaling, but it is not a regulated supply and its output changes with load current.
How to use the Voltage Divider Calculator with Load
Calculate a two-resistor voltage divider, solve for either resistor, or include load resistance to quantify output error and resistor power. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. DC steady state Resistor values are entered in kΩ The load is represented by a resistance from output to ground Ideal voltage source A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- DC steady state
- Resistor values are entered in kΩ
- The load is represented by a resistance from output to ground
- Ideal voltage source
Selection limits and next checks
A resistor divider is a signal-scaling network, not a regulated power supply. Check resistor working voltage, tolerance, temperature coefficient, power rating, input leakage, transient protection, and required isolation. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- DC steady state
- Resistor values are entered in kΩ
- The load is represented by a resistance from output to ground
- Ideal voltage source
Important Warnings
- A resistor divider is a signal-scaling network, not a regulated power supply.
- Check resistor working voltage, tolerance, temperature coefficient, power rating, input leakage, transient protection, and required isolation.