How is holiday entitlement calculated for part-time workers in the UK?

The starting principle

Every UK worker is entitled to 5.6 weeks of paid annual leave, regardless of how many days a week they work. Part-time workers don't get less leave in proportion — they get the same 5.6 weeks expressed in fewer days.

The conversion is simple:

days worked per week × 5.6 = annual entitlement (capped at 28 days)

A 3-day-a-week part-timer gets 16.8 days. A 4-day-a-week part-timer gets 22.4 days. The cap of 28 days only applies when somebody works five days or more a week — for part-timers, it never bites.

Working out hours rather than days

Where the working pattern is variable but predictable, calculate by hours instead:

annual hours × (5.6 ÷ 46.4) = paid leave hours

The figure 5.6 ÷ 46.4 = 12.07% comes up again and again in UK part-time leave calculation. It's the proportion of working time that should be paid as leave.

A part-timer working 20 hours a week (1,040 hours a year) accrues 1,040 × 12.07% = 125.5 hours of paid leave — which is the same as 20 × 5.6 = 112 hours plus a bit of paid bank holiday. The two methods reconcile when bank holidays are included consistently.

Bank holidays — the trap

Bank holidays mostly fall on Mondays. A 4-day-a-week part-timer who never works Mondays would, under a flat pro-rata, get almost no bank holiday benefit at all — even though their full-time colleagues get all eight.

The fix is to pro-rate bank holidays separately from general leave:

1. Calculate full-time annual leave entitlement including bank holidays (e.g. 28 days)
2. Calculate the part-time fraction (e.g. 4/5 = 0.8)
3. Apply the fraction to the total (28 × 0.8 = 22.4 days)
4. Bake the proportional bank holiday entitlement into the worker's general allocation

This way, the part-timer gets the full proportional benefit of bank holidays regardless of which day they fall on.

Irregular hours and zero-hours workers

Workers without a fixed pattern (zero-hours, casuals, term-time-only) accrue holiday at 12.07% of hours worked in each pay period. So a casual who works 40 hours in May accrues 40 × 12.07% = 4.83 hours of paid leave for that month.

When holiday is taken, it's paid at the worker's average hourly rate calculated from a 52-week reference period — averaging weekly pay over the most recent 52 weeks in which they were paid (skipping unpaid weeks, looking back up to 104 weeks if necessary).

The Harpur Trust v Brazel saga

In 2022 the Supreme Court ruled in Harpur Trust v Brazel that part-year workers (such as visiting music teachers working only term-time) couldn't have their leave pro-rated to working weeks — they were entitled to a full 5.6 weeks regardless of how many weeks they actually worked. This was generous to workers but created an obvious anomaly: someone working 25 weeks a year got the same paid leave as someone working all 52.

Parliament responded with the Working Time (Amendment) Regulations 2023, restoring the 12.07% method for irregular-hours and part-year workers from 1 April 2024. The Brazel position no longer applies to leave years starting on or after that date.

Holiday pay calculation

For workers with no normal weekly hours, holiday pay is the average earned in the 52-week reference period above. For workers with regular hours but variable pay (overtime, bonuses, commission), the same averaging applies — UK case law since Bear Scotland v Fulton (2014) has steadily widened what counts as "normal pay" for the 4-week EU-derived portion of leave.

For the additional 1.6 weeks of UK leave, holiday pay can lawfully be calculated on basic pay only — though many employers don't bother with the distinction and pay everything at full average rate for simplicity.

Common edge cases

• Mid-year start — pro-rate the annual entitlement by months remaining in the leave year
• Mid-year leaver — pro-rate up to the leaver date and pay any unused balance
• Compressed hours (e.g. 4-day week with longer days) — calculate by hours rather than days, since each "day off" is longer than a normal day
• Annualised hours — total annual hours stay fixed but distribution varies; accrue leave at 12.07% of hours worked each period and pay at average rate

Putting it into practice

A clean part-time leave policy should:

1. State the leave year explicitly
2. Show the calculation method (days or hours)
3. Pro-rate bank holidays separately
4. Specify the holiday-pay reference period (52 weeks)
5. Cover starters, leavers, and pattern changes mid-year
6. Reference the 12.07% figure for any irregular-hours arrangements

Most disputes around part-time leave come from inconsistent application — using days for some staff and hours for others, or forgetting to pro-rate bank holidays. The arithmetic isn't the hard part. The discipline is.