How to Calculate Pro Rata Annual Leave
Calculating annual leave for part-time employees ensures fairness and compliance with employment laws. "Pro rata" simply means "in proportion." If an employee works half the standard hours of a full-time worker, they are entitled to half the annual leave entitlement.
The Calculation Formula
The standard formula used by this calculator to determine holiday entitlement is based on the proportion of hours worked compared to a full-time standard.
- Step 1: Calculate FTE (Full Time Equivalent)
FTE = Part-Time Hours ÷ Full-Time Hours - Step 2: Apply to Full Entitlement
Pro Rata Entitlement = Full-Time Days × FTE - Step 3: Adjust for Partial Years
If the employee starts or leaves during the year, multiply the result by (Months Worked ÷ 12).
Understanding Statutory Minimums
In many jurisdictions, there is a legal minimum for holiday entitlement. For example, in the UK, almost all workers are legally entitled to 5.6 weeks' paid holiday a year (known as statutory leave entitlement or annual leave). This equates to 28 days for someone working a standard 5-day week.
Part-time workers are entitled to the same amount of holiday as full-time colleagues, calculated on a pro-rata basis. They cannot be treated less favorably simply because they work fewer hours.
Calculating in Hours vs. Days
For employees who work irregular hours or shifts of varying lengths, it is often more accurate to calculate holiday entitlement in hours rather than days. This prevents confusion where a "day" of leave might be interpreted differently depending on the length of a specific shift.
Our calculator provides both the days (based on the average shift length implied by the full-time hours) and the total hours, which is the safest metric for rostering.
Example Calculation
Consider an employee named Sarah:
- Full-time standard: 40 hours/week, 28 days leave.
- Sarah's contract: 24 hours/week.
- Calculation: 24 ÷ 40 = 0.6 FTE.
- Entitlement: 28 days × 0.6 = 16.8 days.
Sarah is entitled to 16.8 days of leave. Employers often round this up to the nearest half-day (e.g., 17 days), but they cannot round it down below the statutory minimum.