How wire size is estimated
The calculator compares the design current with a simplified copper ampacity table and selects the first listed conductor that meets or exceeds the required current.
This is a planning estimate only. Final conductor size must follow applicable electrical codes, equipment ratings, conductor temperature ratings, voltage-drop limits and qualified professional guidance.
Frequently asked questions
Does larger AWG number mean larger wire?
No. For standard AWG sizes, a smaller gauge number generally means a larger conductor.
Is ampacity the only factor in wire sizing?
No. Voltage drop, temperature, insulation, bundling and code requirements can all affect conductor size.
Should I use this result for final installation?
No. Treat it as an estimate and verify the design against applicable electrical requirements.
Using this calculator effectively
This wire size calculator gives a simplified copper AWG estimate from load current using the assumptions shown on the page. It is useful for rough comparison only because allowable ampacity depends on installation conditions and electrical code requirements.
Common uses
- Comparing approximate copper conductor sizes for a stated load.
- Seeing the effect of a continuous-load adjustment where provided.
- Creating a starting point for a discussion with a qualified electrical professional.
Tips for a better estimate
- Do not treat the result as a substitute for an applicable electrical code table.
- Account for insulation temperature rating, conductor count, ambient temperature and installation method.
- Check voltage drop separately on long circuits even when ampacity appears adequate.
Helpful guides
How to Choose Electrical Wire Size · How to Calculate Voltage Drop
Related calculations
Voltage Drop Calculator · Amps to Watts Calculator · Watts to Amps Calculator