Quick answer
UK workers are entitled to 5.6 weeks of paid holiday a year, capped at 28 days. Multiply 5.6 by the days you work: 3 days a week gives 16.8 days and 4 days gives 22.4 days. Irregular-hours workers build up 12.07% of the hours they work.

Statutory holiday in the UK
Almost every worker in the UK is entitled to 5.6 weeks of paid holiday a year. For someone working 5 days a week that's 28 days, which is also the maximum: working 6 days a week still gives 28 days of statutory leave. Your contract can give you more, but never less.
Part-time holiday entitlement
Multiply 5.6 by the days you work each week:
| Days a week | Statutory holiday |
|---|---|
| 1 | 5.6 days |
| 2 | 11.2 days |
| 2.5 | 14 days |
| 3 | 16.8 days |
| 4 | 22.4 days |
| 4.5 | 25.2 days |
| 5 | 28 days |
| 6 | 28 days |
When your days are different lengths
If you work, say, two long days and one short one, holiday in days can be unfair. Working it out in hours is fairer: 5.6 × your weekly hours. For 22.5 hours a week that's 126 hours.
Starting or leaving part way through the year
You get a proportion of the year's entitlement. If you work 5 days a week, your leave year starts on 1 January and you start on 1 September, gov.uk counts 4 months (September to December): 4 ÷ 12 × 28 = 9.33, rounded up to 9.5 days. Someone on 3 days a week who leaves on 30 June has worked 181 of 365 days: 181 ÷ 365 × 16.8 = 8.4 days. This calculator uses the same rules and rounding as gov.uk's own tool.
Irregular hours and part-year workers
For leave years starting on or after 1 April 2024, people with irregular hours (such as zero-hours contracts) and part-year workers build up holiday at 12.07% of the hours they work in each pay period. That figure is 5.6 weeks divided by the 46.4 weeks a year left after holiday. Employers can also pay "rolled-up" holiday pay of 12.07% on top of each payslip for these workers only, shown as a separate line.
Holiday pay
For regular-hours workers, the first 4 weeks of leave must be paid at your normal pay, which includes regular overtime and commission, and the extra 1.6 weeks at basic pay. Irregular-hours and part-year workers get all their leave at normal pay. The holiday pay estimate in the calculator uses your weekly pay ÷ days a week × holiday days, so it is a basic-pay estimate.
Sources: gov.uk holiday entitlement · gov.uk holiday entitlement calculator · gov.uk holiday pay reforms from 2024 · gov.uk part-time workers' holidays