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Electrical Circuit Load Calculator

Check how much of a circuit's safe capacity your connected devices are using, based on the NEC 80% continuous-load rule.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax

Current draw

10 A

High confidence
Total connected load
1200 W
Safe continuous limit (80% rule)
16 A
Safe continuous limit
1920 W
% of safe continuous capacity used
62.5 %

Official municipal inspection prerequisites — United States

Checked against ICC / ACI requirements for the currently selected market. Switching market re-runs these checks.

    These checks cover only the specific thresholds listed above. They are not a complete code review: fire separation, egress, structural capacity and accessibility provisions are outside their scope, and only the handful of local amendments offered in the selector are modelled — your municipality may have others. Final approval rests with your local building authority.

    At the values currently entered, the current draw works out to 10. The largest intermediate quantity is safe continuous limit (80% rule), at 16 A — check that step first if the total looks off. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

    Add the equipment this sizes

    This result is a specification — 10 A — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

    Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

    [Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

    Regulatory standards & verification citations

    • NEC 210.19(A)(1) and 210.20(A): branch circuit conductors and overcurrent protection must be sized so continuous loads (3+ hours) don't exceed 80% of the breaker's rating (equivalently, the 125% sizing rule)

    Your workspace

    Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

    Frequently asked questions

    What counts as a 'continuous' load?
    Per the NEC, any load expected to run for 3 hours or more at a stretch — space heaters, lighting left on for an evening, EV charging, etc. Brief loads like a toaster are non-continuous and can safely use up to 100% of the breaker rating.
    This is telling me I'm over the limit — what should I do?
    Move some devices to a different circuit, or have an electrician evaluate whether a dedicated higher-rated circuit is needed. Don't just install a larger breaker without also upgrading the wiring — the wire, not the breaker, is usually the real limit.
    Is this a substitute for an electrician's load calculation?
    No. This is an educational estimate of one circuit's headroom, not a full panel load calculation, which accounts for diversity factors and code requirements an electrician is trained to apply.
    Where do I find a device's wattage?
    It's usually printed on a label on the device itself or its power adapter. If only amps are listed, multiply by the voltage (usually 120V) to get watts.