Part-time working is incredibly common in the NHS. Whether you're balancing childcare, studying, winding down towards retirement, or simply prefer a shorter week, you're entitled to the same leave benefits as full-time colleagues — just on a proportional basis. But understanding exactly how that proportion is calculated can be confusing, especially when your trust tracks leave in hours rather than days.
This guide walks you through every aspect of pro-rata annual leave for part-time NHS staff under Agenda for Change, with real-world examples you can apply to your own situation.
The pro-rata formula explained
The starting point is simple. Your annual leave entitlement is calculated by comparing your contracted hours to the full-time equivalent of 37.5 hours per week:
(Your contracted weekly hours ÷ 37.5) × full-time entitlement in days = your entitlement in days
For instance, if you work 22.5 hours per week and have 5 years of service (giving a full-time entitlement of 29 days), your calculation is: 22.5 ÷ 37.5 × 29 = 17.4 days.
This seems straightforward, but complications arise when you work variable shift patterns — which is extremely common in clinical NHS roles.
Why most trusts use hours, not days
If you work three 7.5-hour shifts per week, days-based tracking works perfectly: each day off uses one day of leave. But if your pattern includes a mix of long and short shifts — say two 10-hour shifts and one 2.5-hour shift — days-based tracking is unfair. Booking off a 10-hour shift day uses the same 'one day' as a 2.5-hour day, even though the time is vastly different.
Hours-based tracking solves this. Instead of counting days, your leave is expressed in hours, and each absence uses exactly the number of hours you were rostered to work.
Converting days to hours
The conversion is: Entitlement in days × (contracted hours ÷ 5) = entitlement in hours. Using our example above: 17.4 × (22.5 ÷ 5) = 17.4 × 4.5 = 78.3 hours of annual leave per year.
When you book a day off during a 10-hour shift, 10 hours are deducted. When you book off a 2.5-hour shift, only 2.5 hours come off your balance. This ensures fairness regardless of your shift pattern.
Bank holidays for part-time staff
Bank holidays are a separate entitlement on top of annual leave. Part-time workers receive a proportional bank holiday allowance calculated as:
(Your weekly hours ÷ 37.5) × 8 × 7.5 = bank holiday hours
For 22.5 hours per week: 22.5 ÷ 37.5 × 60 = 36 hours. These hours are added to your leave balance and you use them regardless of whether a bank holiday falls on your working day. If it does fall on a working day, the hours are deducted automatically. If it doesn't, you still have the hours to take another time.
A common misunderstanding
Many part-time workers assume they only get bank holiday time off if the bank holiday falls on a day they work. This isn't how it works under Agenda for Change. You receive the proportional hours regardless, and you can use them flexibly throughout the year. This is an important distinction — it means part-time workers aren't disadvantaged simply because their working days don't align with public holidays.
Worked example: 30 hours per week, 10+ years service
Let's work through a complete example for someone contracted at 30 hours per week with over 10 years of continuous NHS service:
- Full-time entitlement: 33 days
- Pro-rata entitlement: 30 ÷ 37.5 × 33 = 26.4 days
- In hours: 26.4 × (30 ÷ 5) = 26.4 × 6 = 158.4 hours
- Bank holiday hours: 30 ÷ 37.5 × 60 = 48 hours
- Total leave: 206.4 hours per year
Divided across 12 months, that works out to approximately 17.2 hours of leave accrued per month. If you start part-way through the leave year, multiply the monthly figure by the number of remaining months.
What happens when you change your hours
If your contracted hours change mid-year — perhaps you drop from 37.5 to 30 hours, or increase from 22.5 to 30 — your leave entitlement needs recalculating. Your trust's HR team should do this automatically, but it's worth checking.
The recalculation typically works by splitting the leave year into two periods: the months at your old hours and the months at your new hours. Each period is calculated separately and added together to give your total entitlement for the year.
If you've already taken more leave than your recalculated entitlement allows, you won't usually be asked to repay it — but you may have fewer hours remaining than expected. Speak with your manager early if you're planning a change of hours.
Compressed hours and annualised hours
Some part-time NHS staff work compressed patterns — for example, their 30 weekly hours over three 10-hour days instead of four 7.5-hour days. This doesn't change your total leave entitlement in hours, but it does affect how many 'days off' you get in practice.
If you work three 10-hour days, each day off uses 10 hours. With 158.4 hours of leave, you could take approximately 15.8 working days off. Compare this with someone working four 7.5-hour shifts: the same 158.4 hours gives them 21.1 working days off. The total time away from work is identical, but the number of calendar days differs.
This is another reason why hours-based tracking is fairer — it removes the distortion created by different shift lengths.
Tips for part-time staff managing their leave
- Always check your leave balance in hours, even if your roster shows it in days. Hours give you the true picture.
- Book leave on your longest shift days if you want to maximise calendar days off. A week off costs fewer hours if you avoid your longest shifts.
- Combine bank holidays strategically. If a bank holiday falls on your non-working day, you bank those hours to extend a holiday elsewhere.
- Use our Annual Leave Calculator to model different scenarios — change the hours and months to see exactly what you're entitled to.
- Ask HR to confirm your balance at the start of each leave year, especially if your hours have recently changed.
Your rights as a part-time worker
Under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000, you have the legal right to the same benefits as full-time colleagues on a proportional basis. This includes annual leave, bank holidays, training opportunities, and access to career development.
If you believe your leave entitlement is being calculated incorrectly, raise it with your line manager, HR department, or union representative. You can also check the calculation yourself using our free Annual Leave Calculator — it uses the exact formula from the NHS Terms and Conditions of Service Handbook.
Calculate your entitlement now
Our Annual Leave Calculator handles pro-rata calculations automatically. Simply enter your contracted weekly hours, years of service, and the period you want to calculate for. The tool gives you results in both days and hours, making it easy to compare with your trust's records. For more information on your overall pay and deductions, try our NHS Pay Calculator.