On average, economics undergraduates receive the equivalent of just 26 hours of one-to-one teaching over a three-year course, research published by the journal Fiscal Studies suggests.
Physics students receive almost three times as much for the same fees.
"It seems a bit bizarre," report author Dr Mike Peacey told the BBC.
"It certainly seems like humanities students are subsidising Stem [science, technology, engineering and maths] students," said Dr Peacey, an economics lecturer at the New College of the Humanities, in London.
"Really, students are paying a kind of university tax rather than tuition fees.
"Maybe that's what you want, but we should be a bit more upfront and honest about this."