The adult education industry in the UK is worth almost Pounds 100 billion a year, according to a Niace inquiry into the future of lifelong learning.
Researchers for the adult education body calculate that annual spending from all sources could be as much as Pounds 2,000 for every adult in the UK, or about Pounds 94bn.
Public investment is put at Pounds 30bn, and employers are estimated to spend Pounds 38bn per year on training. The remainder is invested by the voluntary sector - the most difficult sector to quantify.
Of the overall expenditure, about 95 per cent is spent on education with an economic purpose, although the sum includes higher education provision which may not be directly vocational.
The inquiry found only a small fraction of adult education was for personal development, in line with the Government's philosophy that employment benefits are the main justification for investment in it.
This total dwarfs the Pounds 4bn spent through the Learning and Skills Council on what is traditionally defined as adult education in FE.
Tom Schuller, director of the Niace inquiry, said the small investment in personal development rather than skills for work meant that it was vital for government to keep funding it.
The report was an attempt to map out the full extent of adult education, from its sources of funding to the various recipients, he said.
"We wanted to get a sense of the distribution between the stakeholders - employers, the state, the voluntary sector - as well as within government and its different departments," he said.
"We also wanted to look at the equality of distribution. Until you have this baseline, it's very difficult to make suggestions about how it should be changed."
A final report on the level of investment in learning for over-18s is expected later this year as part of the Niace inquiry, but these figures emerged in the UK national report to Confintea, the international conference on adult education, which takes place in Brazil in May.
The Confintea report said the UK had made substantial progress since the last conference in 1997, particularly in widening access to information, where technology has spread quickly and widely, and in transforming the economy.
Policies designed to get people into work have been successful in creating high labour market participation, the report noted.
"However, concern remains about people with low skills, who are employed but at risk in the event of industrial change," it said.
A priority for this year's conference should be education for the whole person, not just for specific economic, social or cultural objectives, the authors added.
Individuals should have a clear contract with the state and employers about their entitlement to funding, which should provide, as a minimum, literacy, numeracy and technological skills.