--- title: "Voltage Drop Calculator | Electrical Wiring Estimate | XTRAW Tools" description: "Calculate voltage drop in electrical wiring from voltage, current, wire length, and gauge with a free browser-based tool." url: "https://xtraw.com/tools/calculators/science-calculators/voltage-drop-calculator" date: "2026-08-20T11:20:05+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) [![Voltage Drop Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/xtraw-voltage-drop-calculator-360x360.jpg)](https://xtraw.com/images/virtuemart/product/xtraw-voltage-drop-calculator-360x360.jpg "Voltage Drop Calculator from XTRAW Tools") new [Back to: Science Calculators](https://xtraw.com/tools/calculators/science-calculators "Science Calculators") # Voltage Drop Calculator Calculate voltage drop in electrical wiring. Use this free browser-based voltage drop calculator from XTRAW Tools. **Voltage Drop Calculator** helps you calculate voltage drop in electrical wiring. Use this free browser-based calculator from XTRAW Tools to compare inputs, estimate results, and plan your next step. ## How to Use the Voltage Drop 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 drop in electrical wiring. It is designed for electricians, engineers, contractors, students, and people planning wiring estimates who want a fast, browser-based estimate before relying on a contractor, electrician, engineer, code authority, teacher, advisor, or professional source. - Source Voltage: 120 V - Current: 20 A - One-Way Wire Length: 100 ft - Wire Gauge: 12 AWG ## 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. - **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. - **Material Estimating:** Estimate quantities, coverage, materials, and project needs before ordering supplies. ## Formula or Method Vdrop = I × 2L × R/1000; Drop% = Vdrop / V × 100. ## Example **Example inputs:** Source Voltage: 120 V; Current: 20 A; One-Way Wire Length: 100 ft; Wire Gauge: 12 AWG **Example result:** Using the default inputs and approximate 12 AWG resistance, voltage drop is about 6.35 V, or 5.29%. ## Related Tools - [Ohm's Law Calculator](https://xtraw.com/tools/ohms-law-calculator) - [Wire Size Calculator](https://xtraw.com/tools/wire-size-calculator) - [Watts To Amps Calculator](https://xtraw.com/tools/watts-to-amps-calculator) - [Electricity Cost Calculator](https://xtraw.com/tools/electricity-cost-calculator) - [kVA Calculator](https://xtraw.com/tools/kva-calculator) - [Solar Panel Calculator](https://xtraw.com/tools/solar-panel-calculator) ## Voltage Drop Calculator FAQ ### Is the Voltage Drop 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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Use this free browser-based wire size calculator from XTRAW Tools. Custom prototype for related products [![Watts to Amps Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-watts-to-amps-calculator-360x360_230x230.jpg) Watts to Amps Calculator](https://xtraw.com/tools/calculators/science-calculators/watts-to-amps-calculator "Watts to Amps Calculator") Convert watts to amps and estimate current from voltage and power factor. Use this free browser-based watts to amps calculator from XTRAW Tools. Custom prototype for related products [![Electricity Cost Calculator from XTRAW Tools](https://xtraw.com/images/virtuemart/product/resized/xtraw-electricity-cost-calculator-360x360_230x230.jpg) Electricity Cost Calculator](https://xtraw.com/tools/calculators/science-calculators/electricity-cost-calculator "Electricity Cost Calculator") Calculate the cost of running an appliance from watts, runtime, days, and rate. 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