What is Ohm's Law formula?

Ohm's Law states `V = I × R`, where V is Voltage in Volts, I is Current in Amperes, and R is Resistance in Ohms.

How do you calculate power (Watts) using Ohm's Law?

Power can be calculated using three equivalent formulas: `P = V × I`, `P = I² × R`, or `P = V² / R`.

How do you calculate current if voltage is 12V and resistance is 4 Ohms?

Current `I = V / R = 12V / 4Ω = 3 Amperes`. The dissipated power is `P = 12V × 3A = 36 Watts`.

What happens to current if resistance increases while voltage stays constant?

According to `I = V / R`, current is inversely proportional to resistance; increasing resistance causes current to decrease proportionally.

Does Ohm's Law apply to AC circuits?

Yes, for AC circuits with purely resistive loads. For AC circuits with capacitors and inductors, Resistance (R) is replaced by Impedance (Z), accounting for phase shifts.

What are the four primary formulas in Ohm's Law and electrical power?

Voltage: `V = I × R`, Current: `I = V / R`, Resistance: `R = V / I`, and Power: `P = V × I = I² × R = V² / R`.

Science & Engineering Cluster

Ohm's Law Calculator (V = I × R & Electrical Power P = V × I)

Calculate voltage, current, resistance, and electrical power across DC and single-phase AC circuits.

TL;DR: Ohm's Law Calculator solves electrical circuits using Ohm's Law ($V = I \times R$) and Joule's Power Law ($P = V \times I = I^2 \times R = V^2 / R$), resolving any two known variables for the remaining two.

Solve for

Voltage (V)

Current (A)

What Are the Fundamental Formulas for Ohm's Law and Electric Power?

Ohm's Law defines the relationship: Voltage (V in Volts) = Current (I in Amperes) × Resistance (R in Ohms): V = I × R. Electric Power (P in Watts) is calculated as P = V × I = I² × R = V² / R. Knowing any 2 of the 4 parameters allows direct calculation of the other 2.

How to Use the Ohm's Law Calculator

Our Ohm's Law Calculator performs high-precision mathematical operations directly in your browser with zero latency and complete client-side privacy.

Enter any two known electrical values: Voltage (V), Current (I), Resistance (R), or Power (P).
Select units (Volts, Millivolts, Amps, Milliamps, Ohms, Kilo-ohms, Watts, Kilowatts).
Click 'Calculate' to instantly solve for the remaining two unknown electrical parameters.
Review the active formula wheel derivation and step-by-step algebraic steps.
Use results for electronics prototyping, Arduino/Raspberry Pi projects, or electrical sizing.

Mathematical Formula & Equations

Solves voltage ($V$ in Volts), current ($I$ in Amps), resistance ($R$ in Ohms), and electrical power ($P$ in Watts).

\[ V = I \times R, \quad P = V \times I = I^2 R = \frac{V^2}{R} \]

Calculation Example

A circuit with $V = 12\text{V}$ across a $R = 4\,\Omega$ resistor: Current $I = 12 / 4 = 3\text{ Amps}$; Power dissipation $P = 12 \times 3 = 36\text{ Watts}$.

100% Client-Side Privacy & Data Security

All calculations, amortization schedules, variables, and sensitive numerical datasets execute 100% locally in your web browser memory. Your financial, medical, and personal values are never transmitted, logged, or uploaded to any external server.

Frequently Asked Questions

: Ohm's Law states `V = I × R`, where V is Voltage in Volts, I is Current in Amperes, and R is Resistance in Ohms.
: Power can be calculated using three equivalent formulas: `P = V × I`, `P = I² × R`, or `P = V² / R`.
: Current `I = V / R = 12V / 4Ω = 3 Amperes`. The dissipated power is `P = 12V × 3A = 36 Watts`.
: According to `I = V / R`, current is inversely proportional to resistance; increasing resistance causes current to decrease proportionally.
: Yes, for AC circuits with purely resistive loads. For AC circuits with capacitors and inductors, Resistance (R) is replaced by Impedance (Z), accounting for phase shifts.
: Voltage: `V = I × R`, Current: `I = V / R`, Resistance: `R = V / I`, and Power: `P = V × I = I² × R = V² / R`.

Cite This Calculator

Need to reference this online calculator in a financial proposal, academic paper, blog post, or classroom curriculum? Copy a citation below.

NexLove.org. (2026). Ohm's Law Calculator [Online Calculation Tool]. https://nexlove.org/tools/ohms-law-calculator

“Ohm's Law Calculator.” NexLove.org, 2026, nexlove.org/tools/ohms-law-calculator.

NexLove.org (2026) Ohm's Law Calculator. Available at: https://nexlove.org/tools/ohms-law-calculator (Accessed: 2026).

@misc{nexlove_ohms_law_calculator,
  title = {Ohm's Law Calculator},
  author = {{NexLove.org}},
  year = {2026},
  url = {https://nexlove.org/tools/ohms-law-calculator}
}

Embed This Tool

Add the live Ohm's Law Calculator to your own website with this snippet — it loads the real, working calculator in an iframe.

<iframe src="https://nexlove.org/embed/ohms-law-calculator.html" width="100%" height="600" style="border:1px solid #e2e8f0;border-radius:12px" title="Ohm's Law Calculator — NexLove.org" loading="lazy"></iframe>

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