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Understanding School Attendance Percentages in the UK
This is the site’s main guide to school attendance percentages in the UK, written for parents, carers, school staff and attendance teams who want to understand what the number on a school app or letter really means.
Last reviewed: 12 July 2026 by Site editor and maintainer (Paul R).
Reviewed for general accuracy. Always check your school, local authority or official guidance for decisions.
How it works
How attendance percentages are calculated
What an attendance percentage actually means
An attendance percentage is simply the share of possible school time that has been attended so far. If a child attended every possible day or session, the result is 100%. If some time has been missed, the percentage falls to reflect that missed time.
The number does not explain why absence happened. Illness, appointments, anxiety, SEND-related barriers, transport issues and other circumstances can all sit behind exactly the same percentage.
Days versus sessions
Schools often record attendance by session rather than by whole day. A normal day usually has a morning session and an afternoon session, so one full day usually equals two sessions.
That matters because a missed morning, a missed afternoon or another part-day absence can affect the official attendance figure even when a rough day-based estimate feels less precise.
Why 190 school days and 380 sessions are used so often
Across a typical school year, many attendance explainers use about 190 school days as a practical benchmark. When two sessions per day are used, that becomes about 380 possible sessions.
These are useful working assumptions, not promises that every school or every pupil has exactly that total. School calendars, phased timetables and the part of the year you are looking at can all change the official possible total.
Manual attendance calculation formula
The core formula is straightforward: attendance percentage = attended time divided by possible time, multiplied by 100.
Keep the units consistent. Use days with days, or sessions with sessions. If your school report shows sessions, that is usually the better basis for a precise estimate.
- Days version: attended days / possible days x 100
- Sessions version: attended sessions / possible sessions x 100
- One full school day usually equals two sessions
Reference points
What common percentages mean across 190 days
These rounded figures translate a percentage into approximate missed days and sessions.
- 100%
- Days missed0 days
- Sessions missed0 sessions
- ContextNo missed school time in the period shown.
- 97%
- Days missedAbout 5.7 days
- Sessions missedAbout 11 sessions
- ContextA handful of absences across the year.
- 95%
- Days missedAbout 9.5 days
- Sessions missedAbout 19 sessions
- ContextRoughly two school weeks missed in total.
- 90%
- Days missedAbout 19 days
- Sessions missedAbout 38 sessions
- ContextA much larger amount of learning time missed.
- 85%
- Days missedAbout 28.5 days
- Sessions missedAbout 57 sessions
- ContextA substantial amount of time missed across the year.
These are rounded benchmark figures using about 190 school days and about 380 sessions. Exact school totals can differ.
Early-year effect
Why one missed day changes the percentage sharply at first
Early in the year, each missed day or session takes up a bigger share of the total because the denominator is still small. One day missed out of 20 possible days gives 95%, while one day missed out of 190 possible days gives about 99.5%.
That can make school-app percentages feel surprisingly harsh in September or after a short half term, even when the maths itself is working normally.
A single day off is a large share of a short total.
The same absence still matters, but the percentage shock is smaller.
By mid-year, one missed day is spread across a much larger total.
Late-year percentages move more gradually from a single day off.
Across a typical full year, one day is about half a percentage point.
Useful distinctions
Common misunderstandings
Authorised absence can still affect the percentage shown
Parents sometimes assume that authorised absence means the attendance percentage will stay unchanged. In practice, authorised absence may still affect the displayed attendance percentage depending on how the school or MIS system reports possible time and absence codes.
That is another reason the school record matters more than any generic web page when you need the exact figure or the exact interpretation of a code.
Common misunderstandings
A common misunderstanding is that one day always removes the same percentage. It does not. The effect depends on how many possible days or sessions are already in the total.
Another misunderstanding is that a child can return to 100% after absence by attending well for the rest of the year. Once time has been missed, the percentage can improve but cannot return to 100% through attendance alone.
- A high percentage can still represent meaningful learning time missed
- A low-looking early-term percentage does not always mean a large annual problem
- Authorised absence and displayed attendance percentage are not the same thing
- Official school or MIS records outrank site estimates
Next steps
Check your own figures
Use the exact possible days or sessions shown by the school when you calculate an estimate. The school or MIS record remains the figure to rely on if codes or totals have changed.
Guide FAQs
Common questions about this attendance topic
These answers are general information only and are not a substitute for school records or official guidance.
What is a school attendance percentage?
It is the share of possible school time that has been attended so far, usually shown as a percentage of days or sessions.
Why does attendance look worse early in the year?
Because the possible total so far is still small, so each missed day or session makes up a larger share of the calculation.
Should I use days or sessions?
Use sessions if your school report already shows sessions, because that is usually closer to the official record. Use days when you only have day totals and need a broad estimate.
Can authorised absence still affect the attendance percentage?
Yes. Depending on how the school or MIS system displays the record, authorised absence may still affect the attendance percentage shown to families.
Is this page official guidance?
No. It is an independent guide. The official school or MIS record, school policy and current official guidance are the source of truth for decisions.