Some independent-school heads earn as much as pound;100,000 - but others in small schools get just over pound;18,000. The average is pound;48,300.
These figures, gathered last summer, will be under-estimates as most pay rises in independent schools take effect in September.
The median starting salary was just over pound;15,000 (pound;17,650 in London) but some schools, mainly in London and the South-east, were offering more than pound;20,000 to some highly-qualified new teachers.
A basic grade teacher with nine years' experience was on a median salary of pound;22,650 but one London single-sex day-school recorded a salary of pound;33,610 for a teacher at this level - while a day school in the North-west paid only pound;14,160.
Heads of major departments were on average earning pound;28,650. A London single-sex day-school again beat the field with a top salary of nearly pound;48,500.
Many schools paid allowances to top up these basic salaries. Fourteen schools, for instance, gave their heads an entertainment allowance averaging pound;2,250.