NEC Chapter 9, Note 9. A multiconductor cable pulled into conduit counts as a single conductor at its overall diameter, not as the sum of the conductors inside it. That is what the cable tab does, and it is why the figures below are diameters rather than conductor areas.

FPL, FPLR and FPLP are the same cable in different jackets, and their nominal diameters sit very close together, so one table serves all three. What differs is where each may be used: FPLP is plenum rated and is acceptable anywhere, FPLR is for risers, FPL is general purpose and belongs in neither. Shielded versions run roughly 0.01–0.02 in larger than their unshielded equivalents.

A necessary note. Conduit interior areas are from NEC Chapter 9, Table 4; individual conductor areas are from Table 5 (THHN/THWN-2). The fire alarm cable diameters are nominal figures from one manufacturer's published datasheet, and actual outer diameter varies by manufacturer, sometimes significantly. Because Note 9 turns on the actual diameter, verify against the spec sheet for the cable you are really pulling before you size the run. This tool is a planning aid, not a substitute for a code review by a licensed design professional or your authority having jurisdiction.