Kinnaird Primary has almost 300 pupils more than its capacity.
But Falkirk Council said the figures only reflected the capacity of the main school building - and did not take into account the extra places provided by additional units.
It has an additional 299 children on top of its 434 pupil roll - putting its capacity at 168%.
Kinnaird was one of six schools across the district listed as overcrowded.
Denny Primary has a school roll of 336 and a capacity of 284, while Maddiston has 505 pupils when it should accommodate 434 - an extra 71 youngsters.
Beancross Primary has 379 pupils against a capacity of 342, and Westquarter Primary has 365 against a limit of 377.
Larbert High School was the only secondary school identified as overcrowded with 1957 pupils against a capacity of 1872.
The data is based on the latest government school estate data published in September 2021, and represents pupils on the school roll from the previous September.
School capacity is a measure of how many pupils can be taught in a school, and is based on the number and size of teaching spaces available.
Some schools with special units may include these pupils in the overall pupil numbers, but exclude the special unit space from their capacity calculations.
This may make their capacity figures look higher than they are in reality.
A spokesman for Falkirk Council said: “The school capacity figure reported only reflects the capacity of the main school building. It does not include the additional 266 primary places that are provided by modular classroom units on-site.
“This increases the operational capacity of the primary school to 700.
“In addition, the reported pupil census figure of 720 includes 55 additional support needs pupils who are accommodated within two separate establishments.
“The overall capacities of these separate ASN wings are not included in any of the reported overall primary school capacity.
“Therefore the actual school roll is less than primary school operational capacity.”