The distinction in one sentence
Headcount counts each teacher as one person. Full-time equivalent counts a part-time teacher as a fraction of a full-time post. A teacher on three days a week is 1 in headcount and 0.6 in FTE.
Because teachers can change their hours without joining or leaving, the two measures can move in different directions in the same year – and one of them did exactly that in the latest data.
What the data shows
In FTE terms the teaching workforce stands at 466,372, about 5.7% above its 2010/11 level – but it has fallen in each of the last two years.
The part-time share has risen steadily, from 21.5% to 22.7% of teachers over the same period. A rising part-time share means FTE grows more slowly than headcount, mechanically, even if nothing else changes.
The bigger structural change is alongside the teaching workforce rather than within it. Teaching assistants have grown by roughly 73,283 FTE since 2011/12 – an increase of around a third – and total support staff now stand at about 518,200 FTE, more than the teaching workforce itself.
Why the measure you pick changes the story
A report saying the workforce grew and a report saying it shrank can both be accurate if one is counting people and the other is counting posts.
The same ambiguity affects comparisons over time. Because the part-time share has risen, a headcount series will show more growth since 2010/11 than an FTE series will. Neither is wrong; they answer different questions. Headcount answers “how many people work in schools?” FTE answers “how much teaching capacity is there?”
For staffing and timetabling, FTE is almost always the more relevant measure. For questions about the profession as a body of people – its diversity, its age profile, how many are affected by a policy change – headcount is.
Why this matters
It is the single most common source of confusion in workforce reporting, and it is easily avoided: check which measure a figure uses before comparing it with another.
It also matters for planning. If contracted hours continue to drift downward, the number of people a school needs to employ to deliver the same curriculum rises – even with perfect retention and recruitment.
Throughout the Explorer, every workforce figure is labelled with the measure it uses for exactly this reason.