Stringer Calculation Annual Leave: How It Works

Stringer calculation annual leave is a method used to work out an employee’s holiday entitlement when they work irregular hours or a variable number of days per week. You enter the total hours worked over a reference period (usually the previous 52 weeks) and the calculator returns the annual leave entitlement in hours, days, or both, based on the statutory minimum of 5.6 weeks per year. The result tells you how many paid holiday hours the employee has accrued.

Formula

The core formula for stringer calculation annual leave is:

Annual leave hours = (Total hours worked in reference period ÷ 52) × 5.6

Where:

• Total hours worked (t) = the sum of all hours the employee actually worked during the 52-week reference period (in hours).
• 52 = the number of weeks in the reference period.
• 5.6 = the statutory minimum annual leave entitlement in weeks (28 days for a full-time worker working 5 days a week, i.e., 5 × 5.6 = 28 days).

To convert hours into days, you also need the average hours per working day. This is often taken as the employee’s contracted daily hours (e.g., 7.5 hours). The formula becomes:

Annual leave days = Annual leave hours ÷ (average hours per working day)

In the calculator above, the average hours per day is derived from the inputs as (total hours ÷ 52) ÷ days per week, which gives an average daily hours figure.

Worked Example

Using the default values from the calculator:

• Total hours worked in 52 weeks: 1,560 hours
• Days worked per week: 3 days

Step 1: Calculate average weekly hours:

1,560 ÷ 52 = 30 hours per week

Step 2: Calculate annual leave in hours:

30 × 5.6 = 168 hours

Step 3: Convert to days (using average daily hours):

Average daily hours = 30 ÷ 3 = 10 hours per day

Annual leave days = 168 ÷ 10 = 16.8 days

So the employee is entitled to 168 hours or 16.8 days of paid annual leave per year.

When to Use Stringer Calculation

The stringer method (also called the “hours-based� or “accrual� method) is typically used for employees with irregular hours, such as zero-hours contract workers, casual staff, or part-time workers whose schedule changes week to week. It is particularly useful when you cannot easily apply the standard “12.07% of hours worked� rule because the reference period is not a full year.

The calculation is based on the statutory minimum of 5.6 weeks per year, which is the legal minimum in the UK for most workers. Some employers offer more than this, but the statutory minimum is the baseline.

You should use this calculation when:

• The employee works variable hours each week.
• The employee has been employed for less than a full year (the reference period is shortened accordingly).
• You need to calculate leave entitlement for a leaver or for a holiday request.

How to Choose the Reference Period

The reference period is the 52 weeks immediately before the calculation date. If the employee has been employed for less than 52 weeks, you use the number of weeks they have actually worked. For example, if someone started 20 weeks ago, you look at those 20 weeks.

If the employee took unpaid leave or was off sick during the reference period, those weeks are ignored and you go back further to find 52 weeks of actual work. This ensures the calculation reflects the employee’s normal working pattern.

For employees who have a fixed contract but work overtime regularly, you should include only the hours they are required to work, not voluntary overtime, unless the contract states otherwise.

Common Mistakes and Misconceptions

One common mistake is using the calendar year (January to December) as the reference period instead of the 52 weeks before the calculation date. This can lead to incorrect entitlements, especially for new employees.

Another misconception is that the 5.6 weeks entitlement is always 28 days. For a full-time worker working 5 days a week, 5.6 weeks equals 28 days (5 × 5.6). But for a part-time worker working 3 days a week, the entitlement is 16.8 days (3 × 5.6). The stringer calculation handles this automatically because it uses hours, not days.

Also, be careful with rounding. The statutory guidance says you can round up, but not down. For example, if the calculation gives 16.8 days, you should round up to 17 days to avoid underpaying the employee.

Finally, remember that bank holidays are usually included in the statutory minimum. If your employee works variable days, you need to decide how to handle bank holidays—either by giving them as additional days or by including them in the 5.6 weeks.

Limitations of the Stringer Method

The stringer method assumes that the employee’s working pattern in the reference period reflects their future pattern. If the employee’s hours change dramatically (e.g., they move from full-time to part-time), the calculation may not be accurate for the upcoming leave year. In such cases, you may need to recalculate at the start of the new leave year.

The method also does not account for overtime that is not guaranteed. If an employee works occasional overtime, those hours may inflate the average weekly hours and thus the leave entitlement, even though the overtime may not continue.

Additionally, the formula uses 5.6 weeks as the statutory minimum. If your company offers more (e.g., 30 days for full-time), you would replace 5.6 with the equivalent weeks (30 ÷ 5 = 6 weeks).

Alternatives to Stringer Calculation

Another common method is the 12.07% method, which calculates leave as 12.07% of the hours worked in the reference period. This is mathematically equivalent to the stringer method when the reference period is exactly 52 weeks, because 5.6 ÷ 52 = 0.10769 (about 10.77%), but the 12.07% figure comes from 5.6 ÷ (52 – 5.6) = 0.1207. The 12.07% method is simpler for payroll systems because you just multiply each pay period’s hours by 0.1207 to accrue leave.

For employees with a fixed number of days per week, the simpler “days per week × 5.6� method works fine. The stringer method is only necessary when hours vary.

Frequently Asked Questions

How do I calculate annual leave for a zero-hours worker?

Use the stringer method: total the hours worked in the previous 52 weeks (or since employment started if less), divide by 52 to get average weekly hours, then multiply by 5.6 to get annual leave in hours.

Can I round down the annual leave entitlement?

No, you should round up to the nearest hour or day. Rounding down would underpay the employee and could breach statutory minimum requirements.

What if the employee works overtime? Should that be included?

Guaranteed overtime (contracted) should be included. Voluntary overtime that is not guaranteed can be excluded, but if it is regularly worked, it may be considered part of the normal working pattern and should be included.

How do I handle bank holidays for part-time workers?

Bank holidays are included in the 5.6 weeks statutory minimum. For part-time workers, you can either give them a pro-rata number of bank holidays or include them in the overall entitlement. The stringer method gives the total entitlement, so you can deduct bank holidays from that total.

What if the employee has been employed for less than a year?

Use the number of weeks actually worked as the reference period. For example, if they have worked 20 weeks, divide the total hours by 20 and multiply by 5.6 to get their annual leave entitlement for a full year, then pro-rate for the part of the year they have been employed.

Is the stringer method the same as the 12.07% method?

They are mathematically similar but not identical. The 12.07% method uses a percentage of hours worked, while the stringer method uses average weekly hours. The 12.07% method is often easier for payroll, but the stringer method gives the same result when applied correctly over a full year.

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in t | Total hours worked (52 weeks) | hours | 1560 | 0
in d | Days worked per week (average) | days | 3 | 0
out leave_hours | Annual leave entitlement | hours | t * 5.6 / 52 | 2
out leave_days | Annual leave entitlement | days | (t * 5.6 / 52) / (d * 7.5) | 2