The basic rule
Almost all workers are entitled to 5.6 weeks of paid holiday each year. For someone working five days a week that is 28 days. The legal minimum stops at 28 days, so a person working six days a week still gets 28.
Part-time workers
If you work regular hours on fewer days, your entitlement is worked out in proportion. Three days a week gives 16.8 days (three times 5.6). If your days are different lengths, it is often clearer to work in hours: someone working 22.5 hours a week gets 126 hours of holiday.
Bank holidays
There is no legal right to have bank holidays off with pay on top of the 5.6 weeks. Many employers include the eight bank holidays in England and Wales, or the Scottish holidays, within the 28 days. Your contract will say which applies.
Starting or leaving part-way through the year
In your first year, and in the year you leave, entitlement is worked out for the part of the leave year you are employed. When you leave, you should be paid for any statutory holiday you have built up but not taken. Employers can round part days up, but not down.
Irregular hours
People with irregular hours, or who work only part of the year, build up holiday differently. See irregular hours and part-year workers.