You can work out how many days off you should get by multiplying the number of days you work each week by 5.6.
For example, workers who are contracted to work five days a week must get at least 28 days off a year (i.e. 5 days x 5.6) including public holidays. If you are contracted to work three days a week, your leave entitlement will be 16.8 days off a year (i.e. 3 days x 5.6).
You cannot normally be required to work seven days per week. European rules say that workers must have at least a full day of rest a week (though, other than for young workers, they can be taken as two days off every fortnight).
There are no rules on how employers should deal with part days, so they could insist that a worker takes, say, 0.73 of a day's leave. However, the TUC's strong advice is that it would be more sensible for employers simply to round up entitlements to the nearest half-day. The cost of the small extra increase in entitlements is likely to be outweighed by the benefit of having a simple system that is easy to understand and to monitor.
Many people have contractual entitlements that are much better than the statutory minimum. The average GB full-time worker gets 25 days of annual leave plus eight bank holidays. Trade union members tend to do better than those who aren't members. Comparing like-for-like across occupations, industries, and public and private sectors, the average union member gets two days more leave per annum than comparable non-members.