Calculate the correct wire gauge per NEC 2023. Handles temperature correction, conduit fill adjustment, and terminal temperature limits.
Based on NEC 2023 Table 310.16, 310.15(B)-(C), 110.14(C)
Click a preset to auto-fill, or enter custom values below
Applies 125% factor (NEC 210.19)
Correct wire sizing requires satisfying three independent constraints. The largest size required by any of these rules must be installed.
Most equipment terminals are rated for 75°C. You cannot use the 90°C rating of wire as its final capacity if the terminal can only handle 75°C.
High ambient temperatures or many wires in a conduit generate heat. We must derate the wire's 90°C base capacity to find its adjusted safe limit.
Loads running for 3+ hours (AC, Lighting, EV Chargers) require the conductor to be sized at 125% of the actual current.
Common wire sizes for 75°C copper conductors (NEC Table 310.16). Use the calculator above for precise NEC 2023-compliant sizing with all derating factors applied.
*NEC 240.4(D) limits #14/#12/#10 to 15A/20A/30A overcurrent protection.
IMPORTANT LEGAL DISCLAIMER
For Reference Only: This calculator is provided for educational and informational purposes only. It is not intended to be a substitute for professional engineering design, advice, or certification.
Code Compliance: Calculations are based on the 2023 National Electrical Code (NEC®). However, local codes, amendments, and Authority Having Jurisdiction (AHJ) requirements vary by location and may supersede standard NEC requirements.
Verify with Your AHJ: Local Authority Having Jurisdiction (AHJ) requirements take precedence over all general code references. Contact your local building department or electrical inspector to confirm applicable codes, amendments, and permit requirements before beginning any electrical work.
No Liability: SparkShift, LLC and its affiliates assume no liability for errors, omissions, or the use/misuse of this tool. Users are solely responsible for verifying all results against applicable codes and standards before installation. Always consult a licensed electrician or Professional Engineer (PE).
NEC Reference: NEC 2023 Table 310.16, 310.15(B)-(C), 110.14(C)
© 2026 SparkShift, LLC. Calculations are for reference only.
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