Updated · Methodology: named formula library
Wire Size Calculator
Determine the correct wire gauge for an electrical circuit based on amperage and distance.
With 12V and 2A, the resistance is 6 ohms.
Why This Calculation Matters
The Wire Size Calculator helps you price and order materials correctly the first time. Short-ordering means extra trips, delays, and rushed decisions; over-ordering means wasted money and disposal hassle. A precise takeoff, plus a standard 10% waste factor, is the sweet spot.
How to Use This Calculator
- Enter your values in the input fields, each one has a label and help text explaining what to type.
- Results appear instantly as you type; there's no "calculate" button to press.
- Change any input to compare scenarios side by side.
All math happens in your browser. Nothing you type is sent to a server, saved, or shared.
Ordering & Waste Factor
Always add roughly 10% to the calculated quantity. Cuts, edge losses, breakage, and mistakes happen on every project. A small surplus is far cheaper than a supply run mid-pour or mid-install.
Wire Sizing
Wire gauge depends on the amperage and circuit length. Using too-small wire causes voltage drop and overheating.
Common Wire Sizes (copper)
- 14 AWG: Up to 15 amps (lighting circuits)
- 12 AWG: Up to 20 amps (general outlets)
- 10 AWG: Up to 30 amps (dryers, AC units)
- 8 AWG: Up to 40 amps (ranges, large AC)
- 6 AWG: Up to 55 amps (sub-panels)
When to Use This Calculator
- Estimate material quantities before ordering, avoid short-loads and wasteful overbuy.
- Price a bid or budget for a customer accurately.
- Spot errors in a supplier's take-off or quote.
Limitations & Common Mistakes
- Add ~10% to material totals for waste, cuts, and breakage.
- Local building codes, load requirements, and soil conditions may change what you need, always confirm with your permit office or structural engineer.
- Prices vary by region and supplier; request current quotes before ordering.
Frequently Asked Questions
How does the Wire Size Calculator work?
Enter your voltage (v) (default: 12) and any other inputs; the calculator instantly applies its wiring formula and shows the result with details. All math runs in your browser; nothing is sent to a server.
Is the Wire Size Calculator accurate for electrical decisions?
It uses standard, documented formulas that match published references. For high-stakes electrical decisions, verify the result against an authoritative source (industry calculator, professional advisor, or government data). The calculator is a planning estimate, not a substitute for professional judgment.
What inputs does the Wire Size Calculator require?
3 inputs: Voltage (V), Current (A), Resistance (Ω). Each has a sensible default; replace with your own values to get a result tailored to your situation.
Can I bookmark or share the Wire Size Calculator?
Yes — the URL is stable: https://www.calcintel.com/calculator/wiring. Inputs reset to defaults on each visit (no input is stored), so screenshot or copy the result if you want to preserve a specific scenario.
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Source: BLS Consumer Price Index, 2026.