Conduit Fill Calculator
Will it all fit, and what size do you actually need? Worked out by BOTH standards — NEC Chapter 9 and IEC 60364-5-52 — with mixed conductor sizes in one run, and the next trade size up when it does not fit.
The conduit
Auto picks the one your country uses
The tool will suggest a bigger one if this does not fit
Advanced / Custom Input — the conduit
Overrides the table. 0 to use the standard size above.
in
A raceway 24 inches or shorter between two enclosures.
Sources genuinely disagree — see the note in the result.
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What is going in it?
Add a row per size. Mixed sizes are fine — that is what a real pull looks like. Do not forget the equipment ground: it counts for fill even though it does not count for ampacity derating.
Advanced / Custom Input — the conductor list
Replaces the list with a worked starting point.
NEC Note 9: a single jacketed cable counts as ONE conductor, so it gets the 53% limit.
The pull itself
Used for pull-difficulty advice, not for the fill limit itself
m
More than four between pull points is a code problem in most standards
nos
Advanced / Custom Input — the pull
Below this the tool calls it an easy pull. Purely practical advice, not code.
%
For future circuits. Checked against the remaining space.
%
Result
Pick your conduit, add what is going in it, then press “Check the fill”.
Estimate only — verify with a licensed engineer or installer and your local code authority before final design or installation.
1
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in²