Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Electrical & Wiring
Wire Gauge Ampacity Calculator — Size Wire by Load & Length
Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
Suggest wire gauge for a circuit load and check voltage drop against the 3% guideline. Planning estimates only — verify measurements and local codes on site.
Inputs
1200
5500
110480
Smart analysis
Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
- Interpret
Treat this as a planning estimate
Primary result: Suggested wire = 10 AWG. Re-run with optimistic and pessimistic inputs to understand the range—not just a single point.
Scenario studio
Compare A vs B
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Scenario A
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Scenario B
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Load (amps)
The “Load (amps)” value used in this tool’s formula. Adjust it to see results update live.
Circuit length (ft, one way)
The “Circuit length (ft, one way)” value used in this tool’s formula. Adjust it to see results update live.
Voltage (V)
The “Voltage (V)” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Suggest wire gauge for a circuit load and check voltage drop against the 3% guideline. Planning estimates only — verify measurements and local codes on site. Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length. Example: 30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
Example: 30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
When to use this Wire Gauge Ampacity
Common use cases
- Suggest wire gauge for a circuit load and check voltage drop against the 3% guideline.
- Sanity-check with this case: 30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
- The relationship is: Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
Localized examples
- Electrical & Wiring: the example on this page uses the same formula as the widget.
What you get
- Fields: Load (amps), Circuit length (ft, one way), Voltage (V)
- Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
- Example on the page: 30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
How to Calculate Wire Gauge Ampacity Step-by-Step
- 1Enter Load (amps), Circuit length (ft, one way), Voltage (V). Use the values you have, not a catalog average, unless that is all you know.
- 2Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
- 3Worked case: 30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
- 4Buy materials after you walk the job. This is a first-pass quantity, not a purchase order.
Governing formula
Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
30 A load, 80 ft run at 240 V → 10 AWG suggested; ~2.1% voltage drop.
Example: set Load (amps) = 30, Circuit length (ft, one way) = 80, Voltage (V) = 240, then read the result.
Variable definitions
- loadAmps
Load (amps)
The “Load (amps)” field. Default 30; typical range 1–200.
- circuitLengthFt
Circuit length (ft, one way)
The “Circuit length (ft, one way)” field. Default 80; typical range 5–500.
- voltage
Voltage (V)
The “Voltage (V)” field. Default 240; typical range 110–480.
- The takeoff (Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.) ignores waste, code, and what you find when you open the wall. Measure twice on site.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
Match load amps to NEC-style ampacity table; estimate voltage drop over circuit length.
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Community
Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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