Voltage Calculator

What this voltage calculator solves

The page separates voltage solving into three formula modes so each result stays traceable. If you know current and resistance, it uses Ohm's Law directly. If you know power and current, it divides power by current. If you know power and resistance, it applies the square-root relationship that follows from combining Ohm's Law with the power equation.

Keeping those modes distinct matters because the arithmetic and failure cases are not the same. For example, the power-current mode cannot divide by zero current, while the power-resistance mode requires a positive resistance value.

The three voltage formulas on this page

Voltage can be solved directly from Ohm's Law or from equivalent power relationships. The calculator shows the exact equation it used so you can verify the numbers or copy the working into a design note.

Practical uses for a solved voltage

A voltage result can help you check whether a resistor network matches a supply target, whether a load is being driven within its expected range, or whether a stated wattage and current imply a realistic operating voltage.

That makes this calculator useful as a bench-side verification step, especially when troubleshooting a simple resistive circuit or checking whether a planned power supply is in the right range.

Where this model stops

This is an ideal resistive model only. It does not account for AC impedance, phase angle, regulator behaviour, semiconductor forward voltage, motor characteristics, or transient conditions.

Use it as an educational and planning estimate, then confirm the result against actual component specifications and the full circuit context before finalizing a design.