Pro Rata Vacation Calculator | UK Holiday & US PTO

Whether you work part-time, started a new job mid-year, or are leaving before your contract ends, knowing exactly how much vacation time you have earned is not just useful — it is your legal right. This free pro rata vacation calculator works out your precise holiday entitlement for both UK workers and US employees, covering part-time hours, part-year service, and every scenario in between.

What Does Pro Rata Vacation Mean?

“Pro rata” is Latin for “in proportion.” Applied to vacation or holiday entitlement, it means your leave is scaled proportionally to either the hours you work (compared to a full-time employee) or the portion of the year you have been employed.

In the UK, the legal term is holiday entitlement, and the statutory minimum under the Working Time Regulations 1998 is 5.6 weeks per year. For a standard five-day week, that equals 28 days. Part-time workers receive the same 5.6 weeks, but calculated against their own working pattern — so a three-day-a-week employee is entitled to 5.6 × 3 = 16.8 days per year.

In the US, there is no federal statutory minimum for paid vacation. The Fair Labor Standards Act (FLSA) does not require employers to offer paid leave. However, most employers voluntarily offer paid time off (PTO), and the IRS considers accrued PTO a form of deferred compensation. When an employee starts mid-year or leaves early, pro rata PTO calculations determine what they have earned.

How to Calculate Pro Rata Vacation Entitlement

There are two distinct scenarios where you need a pro rata vacation calculation:

Scenario 1: Part-Time Hours (Working Fewer Hours Than Full-Time)

This is the most common use case. The formula is:

Pro Rata Leave = Full-Time Leave Entitlement × (Your Weekly Hours ÷ Full-Time Weekly Hours)

Worked example (UK):

• Full-time entitlement: 28 days (including bank holidays)
• Full-time hours: 37.5 per week
• Your hours: 22.5 per week
• Ratio: 22.5 ÷ 37.5 = 0.6 (60%)
• Pro rata entitlement: 28 × 0.6 = 16.8 days

In hours: 16.8 × 7.5 hours per day = 126 hours

Worked example (US):

• Employer offers 15 days PTO for full-time (40 hrs/week)
• Employee works 24 hours per week
• Ratio: 24 ÷ 40 = 0.6 (60%)
• Pro rata PTO: 15 × 0.6 = 9 days

Scenario 2: Part-Year Service (Starting or Leaving Mid-Year)

When an employee starts or leaves part-way through the leave year, entitlement is further adjusted by the fraction of the year they work.

Pro Rata Leave = Full Entitlement × (Hours Ratio) × (Weeks Worked ÷ 52)

Worked example (UK) — employee joins in October:

• Full-time entitlement: 28 days
• Employee works full-time (ratio = 100%)
• Weeks remaining in leave year: 26 weeks
• Part-year factor: 26 ÷ 52 = 50%
• Entitlement: 28 × 100% × 50% = 14 days

ACAS provides useful guidance on holiday entitlement for workers starting or leaving mid-year, including rules on carrying over unused leave.

Worked example (US) — employee joins July 1st:

• Employer offers 10 days PTO per year
• Employee starts halfway through the year: 26 ÷ 52 = 50%
• Pro rata PTO: 10 × 50% = 5 days

Note that US employers often specify whether PTO accrues from day one or after a probationary period. Always check your employee handbook.

UK vs US: Key Differences in Vacation Entitlement

Understanding the legal framework in each country avoids costly mistakes.

Factor	UK	US
Statutory minimum	5.6 weeks (28 days for 5-day week)	None (employer-set)
Legal framework	Working Time Regulations 1998	Fair Labor Standards Act (FLSA)
Part-time rights	Same 5.6 weeks, pro rated by hours	Employer discretion
Bank holidays	Can be included in 28-day minimum	Employer discretion
Carry-over	Limited by contract; WTR rules apply	Employer policy (“use it or lose it” common)
Leaving employment	Unused leave must be paid out (UK)	Varies by state (US)
Reference body	gov.uk / acas.org.uk	IRS.gov / state labor boards

In the UK, it is unlawful for an employer to pay in lieu of statutory leave except on termination of employment. In the US, states like California require unused accrued PTO to be paid out when an employee leaves; other states do not.

Bank Holidays and Pro Rata Vacation

In the UK, many employers include the 8 public bank holidays within the 28-day statutory minimum. If your employer does this, and you work part-time, you are entitled to a pro rata share of bank holidays too.

Example: A part-timer working 3 days out of 5 is entitled to 3/5 of 8 bank holidays = 4.8 bank holidays. If a bank holiday falls on a day they do not work, they are still entitled to the time off equivalent.

Our pro rata bank holiday calculator handles this specific calculation in detail.

Pro Rata Vacation When Leaving a Job

When an employee leaves before the end of the leave year, their entitlement is calculated to the date of leaving. In the UK:

• If they have taken more leave than accrued, the employer may (if the contract allows) deduct the excess from final pay
• If they have taken less leave than accrued, the employer must pay the balance

Use our pro rata holiday calculator for leavers for a dedicated tool covering termination scenarios, including garden leave and payment in lieu.

Pro Rata Vacation for Term-Time Workers

Teachers, teaching assistants, and other term-time workers have a more complex calculation because they work fewer weeks per year. A term-time worker employed for 39 weeks would have their entitlement calculated as:

Leave = 5.6 weeks × (39 ÷ 52) = 4.2 weeks

See our pro rata term-time salary calculator for combined salary and leave calculations for term-time contracts.

Calculating Pro Rata Vacation in Hours vs Days

The UK government’s own holiday entitlement tool on gov.uk allows calculation in either hours or days. If your working day is not a standard length, calculating in hours is more accurate.

Converting days to hours:

Hours entitlement = Days entitlement × Hours per working day

For a part-timer working 6-hour days with 16.8 days entitlement: 16.8 × 6 = 100.8 hours

Our pro rata holiday hours calculator and pro rata holiday calculator (hours) cover this in full.

Pro Rata Salary and Vacation Together

Part-time workers often need both their salary and their leave calculated at the same time. If a full-time salary is £35,000 for 37.5 hours, a 25-hour employee earns:

• Pro rata salary: £35,000 × (25 ÷ 37.5) = £23,333
• Pro rata leave: 28 × (25 ÷ 37.5) = 18.67 days

Our pro rata salary calculator and calculate full-time salary from pro rata tools handle the salary side of this equation.

Common Mistakes to Avoid

1. Not including bank holidays correctly. If your contract says 20 days plus 8 bank holidays, your total is 28 days — the statutory minimum. Pro rating just the 20 days and leaving bank holidays at the full 8 is incorrect for genuine part-timers.

2. Using calendar days instead of working days. Pro rata vacation calculations are always based on working days or working hours, never calendar days.

3. Forgetting the part-year adjustment. Part-time ratio and part-year adjustment are two separate multipliers, both of which may apply simultaneously.

4. Rounding too early. Always carry full decimal places through the calculation and round only the final result, ideally to the nearest half-day.

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Frequently Asked Questions

How do I calculate pro rata vacation days?

Multiply the full-time annual leave entitlement by your part-time ratio (your hours divided by full-time hours). If you also work part of the year, multiply the result again by the fraction of the year worked (weeks worked divided by 52). For example: 28 days × (22.5 ÷ 37.5) × (39 ÷ 52) = 14 days.

What is the UK statutory minimum holiday entitlement?

The UK statutory minimum is 5.6 weeks per year under the Working Time Regulations 1998. For a five-day week, this equals 28 days. Employers can include the 8 public bank holidays within this figure. Part-time workers receive the same 5.6 weeks pro rated to their working pattern.

Do part-time workers get less holiday in the UK?

Part-time workers receive the same 5.6 weeks entitlement as full-time workers, but calculated against their own working week. A three-day-a-week worker gets 5.6 × 3 = 16.8 days, not 28 days. This is equal treatment — the same number of weeks, just fewer days.

Is there a legal minimum vacation in the US?

No. The Fair Labor Standards Act does not require US employers to provide paid vacation or PTO. It is entirely employer-discretionary. Some states have enacted their own paid leave laws, but there is no federal equivalent to the UK’s Working Time Regulations.

How is pro rata holiday calculated when leaving a job in the UK?

In the UK, when an employee leaves, their holiday entitlement is calculated to the leaving date. The formula is: (Days worked in leave year ÷ Total days in leave year) × Annual entitlement. Any accrued but untaken leave must be paid out at the employee’s daily rate of pay. See acas.org.uk for full guidance.

How do I calculate pro rata vacation in hours?

First calculate your entitlement in days using the pro rata formula, then multiply by the number of hours in your working day. If you are entitled to 16.8 days and your day is 7.5 hours, your entitlement is 16.8 × 7.5 = 126 hours. Use our pro rata holiday hours calculator for an automatic result.

What happens to unused pro rata vacation when I leave a job in the US?

This depends on your state. In California, accrued PTO is treated as earned wages and must be paid out on termination. In states like Florida and Texas, employers can enforce “use it or lose it” policies and are not required to pay out unused PTO. Always check your employment contract and state labor laws.

Can my employer round down my pro rata holiday entitlement?

In the UK, employers cannot round down holiday entitlement. They may round up to the nearest half or whole day as a matter of convenience, but rounding down would reduce the statutory minimum entitlement, which is unlawful. See gov.uk holiday entitlement rights for the official position.