Voltage Drop Calculator — Free Online Tool
Voltage loss over wire length
Calculate voltage drop across a wire run. Copper or aluminum, single or three phase. Critical for code compliance.
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Voltage drop
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Voltage drop calculator
Calculate voltage loss across a wire run. Meet NEC 3% recommendation.
How to use this tool
- 1
Enter current (amps)
Load current the circuit carries.
- 2
Enter wire length
One-way distance from source to load.
- 3
Pick AWG + material
See voltage drop + percentage.
Frequently Asked Questions
What is acceptable voltage drop?
NEC recommends max 3% for branch circuits, 2% for feeders. Combined total should not exceed 5%.
Single vs three phase formula
Single phase: Vdrop = 2 × I × R × L. Three phase: Vdrop = √3 × I × R × L. Three-phase has lower drop for same load.
Key Takeaways
- Voltage Drop Calculator is a free, browser-based calculator tool — voltage loss over wire length.
- No signup, no downloads, no file uploads. Tools run in your browser; the few that need an outside service say so on the page.
- Works on desktop, tablet, and mobile. Install as a PWA for offline access.
How to Use Voltage Drop Calculator
- Open the tool: Launch Voltage Drop Calculator on Toololis — no account or download needed.
- Enter your data: Paste text, enter values, or select a file directly in your browser.
- Get instant results: Everything is processed locally — results appear immediately.
- Copy or download: Save your output or share it. Bookmark for quick access next time.
Voltage Drop Calculator — Quick Facts
- Price
- Free — no limits, no watermarks, no paywalls
- Privacy
- Processed in your browser. Tools that need an outside service say so on the page. Page views are counted (Google Analytics).
- Platform
- Any modern browser on desktop, tablet, or mobile
- Category
- Calculator Tools on Toololis
- Offline
- Works offline after first visit (Progressive Web App)
| Feature | Details |
|---|---|
| Tool | Voltage Drop Calculator |
| Category | Calculator |
| Signup Required | No |
| File Upload | None — processed in browser |
| Mobile Support | Fully responsive |
| Cost | Free forever |
Why Use Voltage Drop Calculator?
You should try Voltage Drop Calculator for a quick, private way to voltage loss over wire length. Processing happens in your browser and files are never uploaded; the few tools that need an outside service say so on the page.
On the other hand, dedicated APIs or desktop tools suit batch processing better. They also handle server-side automation. For everyday tasks, browser tools offer the best speed, privacy, and convenience.
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100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.