NSW independent schools had an average income per student of $16,631 compared with $12,118 for government schools and $11,747 for Catholic diocesan schools in 2012, the most recent year available.

The findings come from an analysis of the My School website - commissioned by the Australian Education Union - by education consultant and former primary school principal Bernie Shepherd.

Since 2009, the average income per student has increased by 12 per cent in the independent and public sectors and by 14 per cent in Catholic schools.

Catholic schools received the biggest percentage boost in 2012, thanks largely to a 19 per cent increase in fees. Average income per student in NSW Catholic schools increased by 6.8 per cent year-on-year, compared with 4.5 per cent for government schools and 2.3 per cent for independent schools. NSW public schools received an average $11,517 in government funding per student, Catholic schools $9254 and independent schools $7479.

Nationally, independent schools had an average income per student of $15,997 compared with $12,368 for government schools and $11,709 for Catholic schools. Public schools educate the majority of indigenous students, students with disabilities, students from low socio-economic backgrounds and students with English as a second language.

But My School shows that students at high-fee private schools do not necessarily outperform their public school counterparts.

For example, students at Woollahra Public School, with an income per student of $8662, performed better in the latest NAPLAN reading and numeracy tests than at nearby Reddam House, with an income per student of $21,762.

AEU federal president Angelo Gavrielatos said the figures ''prove the case and highlight the urgency for the needs based funding recommended by [David] Gonski. We believe that all schools should be funded according to need.'' A spokesman for the Independent Schools Council of Australia said that independent schools relied heavily on government funding to meet the increasing costs associated with delivering education results as after enrolment and cost increases many independent schools were still facing financial pressures.

Executive director of the National Catholic Education Commission, Ross Fox said Catholic schools operated with about 80 per cent of the government funding per student available in a government school. Despite this funding gap, Catholic schools welcome thousands of students with special needs, indigenous students and many from disadvantaged backgrounds.