A survey of 3,000 primary and secondary school students in England showed 27% of them had a private tutor.
Primary school pupils are mainly getting extra help to get them into secondary schools, and most older pupils are having it for their GCSES.
Maths and English came top of the list of subjects where pupils wanted help.
Researchers found most pupils had extra lessons to improve their grades in exams rather than because they need to catch up.
One secondary school reported that 65% of one year group were having private tuition, while a primary school had 59% of pupils getting extra lessons.
Your views on out-of-schools lessons
Have you ever had private tuition?
Students should decide subjects at school
