Conduit fill calculator
Put in the wires you're pulling. See how full the pipe gets, whether it passes, and the smallest size that takes them.
Fill charts
The most wires of one size each conduit takes, from Annex C's rule: 40 % of the inside area, rounded up at 0.8.
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How the count works
Each conduit type and size has an inside area (Chapter 9, Table 4). Each wire has an area with its insulation (Table 5). Three or more wires may fill 40 % of the conduit, two wires 31 % and one wire 53 % (Table 1). A nipple of 24 in or less may fill 60 %.
When every wire is the same size, a count that comes out at 0.8 or more rounds up (Note 7): 21.98 #14 THHN in 3/4" EMT is 22. With mixed sizes there is no rounding; the total area has to stay under the limit. Grounds and neutrals count toward fill like any other wire.