--- title: "Ohm's Law Calculator | Voltage Current Resistance Tool | XTRAW Tools" description: "Calculate voltage, current, resistance, or power using Ohm's law with a free browser-based electrical calculator." url: "https://xtraw.com/tools/calculators/science-calculators/ohms-law-calculator" date: "2026-05-21T23:56:00+00:00" language: "en-GB" --- [Wire Size Calculator](https://xtraw.com/tools/calculators/science-calculators/wire-size-calculator)[Capacitor Calculator](https://xtraw.com/tools/calculators/science-calculators/capacitor-calculator) [![Ohm's Law Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/xtraw-ohms-law-calculator-360x360.jpg)](https://xtraw.com/images/virtuemart/product/xtraw-ohms-law-calculator-360x360.jpg "Ohm's Law Calculator from XTRAW Tools") popular [Back to: Science Calculators](https://xtraw.com/tools/calculators/science-calculators "Science Calculators") # Ohm's Law Calculator Calculate voltage, current, resistance, or power using Ohm's law. Use this free browser-based ohm's law calculator from XTRAW Tools. **Ohm's Law Calculator** helps you calculate voltage, current, resistance, or power using Ohm's law. Use this free browser-based calculator from XTRAW Tools to compare inputs, estimate results, and plan your next step. ## How to Use the Ohm's Law Calculator 1. Enter the required calculator inputs shown in the form. 2. Review the measurements, electrical values, grades, weights, rates, or reading assumptions. 3. Run the calculator, then adjust one input at a time to compare scenarios or check your work. ## What This Calculator Helps With Calculate voltage, current, resistance, or power using Ohm's law. It is designed for students, electricians, electronics hobbyists, engineers, and STEM learners who want a fast, browser-based estimate before relying on a contractor, electrician, engineer, code authority, teacher, advisor, or professional source. - Voltage: 12 V - Resistance: 4 Ω - Current: optional ## Common Uses People use this calculator when they need a quick way to estimate construction materials, electrical values, solar sizing, school grades, GPA, or reading time from real inputs. - **Math Solving:** Apply formulas to solve grade, physics, electrical, or school-related calculations. - **Measurement:** Use measurements, grades, electrical values, or reading values to get a clear result. - **Project Planning:** Compare project assumptions, academic goals, energy plans, or electrical scenarios. ## Formula or Method V = I × R; P = V × I. ## Example **Example inputs:** Voltage: 12 V; Resistance: 4 Ω; Current: optional **Example result:** Using 12 V and 4 Ω, current is 3.00 A and power is 36.00 W. ## Related Tools - [Voltage Drop Calculator](https://xtraw.com/tools/voltage-drop-calculator) - [Watts To Amps Calculator](https://xtraw.com/tools/watts-to-amps-calculator) - [LED Resistor Calculator](https://xtraw.com/tools/led-resistor-calculator) - [Capacitor Calculator](https://xtraw.com/tools/capacitor-calculator) - [kVA Calculator](https://xtraw.com/tools/kva-calculator) - [Electricity Cost Calculator](https://xtraw.com/tools/electricity-cost-calculator) ## Ohm's Law Calculator FAQ ### Is the Ohm's Law Calculator free? Yes. This calculator is free to use on XTRAW Tools. ### Do I need to create an account? No. XTRAW tools are designed for browser-based use without requiring an account. ### Are the results exact? Results may be estimates depending on the inputs, formula, rounding, assumptions, and purpose of the calculator. Always verify important results before relying on them. **Disclaimer:** This calculator is provided for general informational, educational, and convenience purposes only. It is not legal, financial, medical, tax, engineering, electrical, construction, solar, academic, safety, or professional advice. 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