Almost half of the UK's students take on part-time work in term-time, earning £2.3bn a year, a study suggests.
Bar work is a popular part-time occupation for many students
Students worked an average of 16 hours a week, with 20% doing more than 20, the Royal Bank of Scotland (RBS) found.
The research found those in Belfast and Glasgow were most likely to have a job - 62% and 60% respectively.
Cardiff was judged the most cost-effective place to study, while Cambridge was the least. Some 2,648 students in 26 towns were interviewed.
Those in Leeds worked the longest hours at 21 a week, while those in Durham worked the least time (12.4 hours).
MOST COST EFFECTIVE TOWNS
Source: RBS survey
The most popular part-time jobs were in bars and clothes shops, but more unusual occupations included turf accountants, life guards and charity fundraisers, the RBS found.
And more than half of undergraduates (52%) still underestimated the cost of living.
Food and music
The RBS found that, over the next year, students would spend £10bn on accommodation and living costs.
Of this, approximately £3.7bn would go on rent, £995m on supermarket food shopping, £688m on going out, £404m on books and course materials and £306m on music and CDs.
LEAST COST-EFFECTIVE TOWNS
The bank's student living index ranked major university towns according to cost-effectiveness.
It plotted expenditure on living and housing costs against income from jobs.
At the top end of the scale, the average student in Cardiff spent £188 per week on living and housing costs, but earned £131 from part-time work.
At the other end, the average student in Cambridge spent £206 per week, but made just £69 from employment.
Cambridge University strongly recommends to its students that they do not take on paid work during term time. However, many students at the university also benefit from bursaries and hardship funds.
A Cambridge University spokeswoman said: "The survey reflects the cost of living of students in the city of Cambridge generally.
"University of Cambridge students were not the only ones from the city to contribute to the findings.
"One of the great advantages of studying at the University of Cambridge is that, unlike other universities, students can usually live in college accommodation for the duration of their degree.
"This means they don't have to pay rent during vacation periods, they don't have to pay deposits and they don't have to pay private sector rates of rent.
"Annual rents at the University are, therefore, often much lower than those paid by students at other universities, who are tied into 12-month contracts with private sector landlords.
"In addition, Cambridge students benefit from some of the most generous financial support in the country, thanks to the bursaries and hardship funds provided by the university and colleges."
After being bottom of the cost-effectiveness index last year, St Andrews has climbed to fourth place.
A similar trend is apparent in Edinburgh, now in seventh place up from 19 last year, and in Bristol, at number 10 compared with 23rd last year.