Primary and prep schools: What's the difference?
Primary schools are state-funded and free, taking children from age 4 to 11. Prep schools are fee-paying independent schools that typically take children from 7 (or earlier with a pre-prep) up to 11 or 13, depending on the school. The biggest day-to-day differences are cost, class size, and what the school is preparing your child for at the end of it.
This guide walks through each of those differences and ends with the practical question many parents are really asking: Which one suits your child, and how to decide.
Primary vs prep schools at a glance
| Feature | Primary school | Prep school |
|---|---|---|
| Funding | State-funded, free to attend | Independent, fee-paying |
| Age range | 4 to 11 (Reception to Year 6) | 7 to 11 or 7 to 13 (with pre-prep 4 to 7) |
| Annual fees | Free | Roughly £15,000 to £40,000+ a year, plus extras |
| Curriculum | National Curriculum (KS1 and KS2) | Often follows National Curriculum but with significant additions and flexibility |
| Class size | Up to 30 (legal cap for infants), often 30 in KS2 | Typically 16 to 22 |
| End-of-school assessment | SATs in Year 6 | ISEB Pre-Test or Common Entrance, plus school-specific exams |
| Next stage | State secondary, grammar (with 11+), or private senior | Independent senior school at 11+ or 13+ |
Age ranges and exit points
State primary schools run from Reception (age 4) to Year 6 (age 11). Every pupil finishes at the same point and moves on to a secondary school at 11.
Prep schools are more varied. Some run from 7 to 11, mirroring the primary exit point. Others run from 7 to 13, with pupils leaving for senior school at the end of Year 8 rather than Year 6. The 13+ route exists because many traditional independent senior schools (Eton, Winchester, Harrow, Tonbridge and others) historically take pupils at 13. Many prep schools also have a pre-prep attached, covering ages 4 to 7, which means a child can stay in the same group of buildings from 4 to 13.
If you're considering a prep school, check its exit age before applying. A 7-to-13 prep school commits you to a senior school that takes pupils at 13+, which narrows your options compared to leaving at 11.
What does each cost?
State primary schools are free. There are usually small charges for trips, after-school clubs and lunches if your child doesn't qualify for free school meals, but the headline cost is zero.
Prep school fees in 2026 range broadly from around £15,000 to well over £40,000 a year. Mid-market preps sit in the £15,000-£25,000 band, while leading London and southeast preps (Westminster Under, Latymer Prep, Dragon School and similar) frequently exceed £30,000, with the most established London preps now above £40,000. Boarding preps add another £10,000 to £20,000 on top. On top of headline fees, expect extras for trips, music lessons, uniform and lunch.
Since 1 January 2025, VAT at 20% applies to private school fees, including prep schools. Many schools absorbed part of the increase by trimming underlying fees, so a number of parents have faced a net rise below the full 20%, while others have seen close to the full pass-through. The mix varies considerably school-by-school, so always check the post-VAT figure on the school's current fees page.
Curriculum: What gets taught?
State primary schools must follow the National Curriculum. That means a defined programme of study for English, maths, science, history, geography, art, music, PE, computing, design technology and religious education, plus a modern foreign language from Year 3.
Prep schools aren't required to follow the National Curriculum, though many do as a baseline. The difference is what gets added on top. Latin from Year 4 or 5 is common at academically selective preps. Some schools teach French from Reception. Drama, debating, philosophy and chess often appear as timetabled subjects rather than after-school clubs. The result is a broader timetable, but it also means more hours in the school day.
Class size and teaching
Class sizes are one of the most visible differences. State primary schools have a legal cap of 30 in infant classes (Reception, Year 1, Year 2) and most run at or near that cap throughout KS2 as well. Prep schools typically run classes of 16 to 22, with some setting smaller groups for maths and English from Year 4.
The practical effect is more individual attention per pupil at a prep, particularly in the older years when work gets harder and personalised feedback matters more. State primary teachers are doing the same job, but with more children to track.
Exam preparation: SATs vs ISEB and Common Entrance
What your child sits at the end of primary or prep is where the routes really diverge.
State primaries prepare pupils for SATs in Year 6, the standardised assessments in English and maths that produce a scaled score used by secondary schools to set classes. SATs results don't determine which secondary school you go to. That's based on the council's admissions process.
Prep schools prepare pupils for the ISEB Common Pre-Test (a computer-based assessment in English, maths, verbal and non-verbal reasoning) at 10 or 11, followed for the 13+ route by Common Entrance exams in a broader range of subjects. Some senior schools also set their own admissions exams. Prep schools build this preparation into the timetable from Year 4 or 5, not as bolt-on after-school sessions.
Which route suits which child?
There's no universal answer. The decision usually comes down to four factors. Cost, your child's intended next school, the local state options, and your child's temperament.
If your strongest local primary is well-regarded and your secondary plan is the local state secondary or grammar route, state primary is usually the better-value choice, with no compromise on outcomes. If your plan is a selective independent senior school at 11+ or 13+, a prep school's targeted preparation, smaller classes and broader curriculum can give a meaningful head start, though dedicated 11+ tutoring alongside a strong state primary is also a workable path.
Temperament matters too. Some children thrive in larger, more diverse settings. Others do better in smaller, more structured environments. Visit both before deciding.
Choosing between primary and prep
Work through these before applying. The right answer differs by family.
- Confirm your post-7 plan: state secondary, grammar (11+), or independent senior
- Cost out prep fees post-VAT, including extras, against your household budget
- Visit your strongest local state primary alongside any prep options
- Check the prep school's exit age (11+ or 13+) and onward destinations
- Look at the ISI inspection report for the prep school in full
- Ask current parents at both schools about a typical day, not just open day pitches
- Consider commute: prep schools often have wider catchments and longer journeys
- Decide whether your child suits a larger or smaller class setting
