How to Calculate Remaining Holiday Hours

Step 1: Find your total holiday allowance

Start with the total holiday allowance given to you by your employer or shown in your leave system.

It might be shown as:

• 120 hours
• 180 hours
• 202h 30m

This page assumes you already know your allowance.

It is designed to help you work out what is left, not to calculate how much annual leave you are legally entitled to.

Step 2: Subtract leave already taken

To find your remaining entitlement, subtract the leave you have already used.

The formula is:

Total allowance − leave taken = remaining entitlement

For example:

• Total allowance: 180 hours
• Leave taken: 52h 30m

180h − 52h 30m = 127h 30m

So after taking 52 hours 30 minutes of leave, you have 127h 30m remaining.

Step 3: Subtract leave already booked

If you have future leave booked, you may also want to remove that from the balance to see what is still available to book.

For example:

• Remaining entitlement: 127h 30m
• Future leave already booked: 30h

127h 30m − 30h = 97h 30m

So 97h 30m is still available to book.

This is different from your total remaining entitlement because some of that remaining leave has already been allocated to future dates.

Remaining entitlement vs available to book

These two figures are often confused.

Remaining entitlement

This is the total leave you have not yet taken.

Formula: Allowance − leave taken

180h − 52h 30m = 127h 30m

Available to book

This is the leave that has not yet been taken or already booked.

Formula: Allowance − leave taken − leave booked

180h − 52h 30m − 30h = 97h 30m

Some employer systems automatically subtract booked leave from the balance they display. Others may show booked leave separately.

Before doing your own calculation, check what your current balance actually represents so you do not subtract booked leave twice.

Worked example in hours and minutes

Suppose your annual leave allowance is 120h 30m, and you have already taken 37h 45m.

The remaining entitlement is:

120h 30m − 37h 45m = 82h 45m

Now suppose you also have 15 hours of future leave booked.

Available to book:

82h 45m − 15h = 67h 45m

So the figures are:

• Total allowance: 120h 30m
• Taken: 37h 45m
• Remaining entitlement: 82h 45m
• Booked: 15h
• Still available to book: 67h 45m

The same calculation in decimal hours

You can also carry out the same calculation using decimal hours.

For example, 120h 30m = 120.50 hours and 37h 45m = 37.75 hours.

Then:

120.50 − 37.75 = 82.75 hours

The decimal part 0.75 means 45 minutes.

So: 82.75 hours = 82h 45m

This can be useful if your employer or leave system records holiday in decimal hours.

How to subtract hours and minutes

If the minutes in the second value are larger than the minutes in the first, you may need to borrow one hour.

For example:

120h 30m − 37h 45m

You cannot subtract 45 minutes directly from 30 minutes, so borrow one hour. 120h 30m becomes 119h 90m.

Then:

• 90m − 45m = 45m
• 119h − 37h = 82h

So the answer is 82h 45m.

If you prefer, you can avoid manual borrowing by converting both values into decimal hours first.

What if your holiday balance goes below zero?

A negative holiday balance can happen.

For example:

• Holiday allowance: 100h
• Leave taken and booked: 106h

100 − 106 = −6h

This gives −6 hours.

A negative balance could mean:

• more leave has been booked than is currently available
• your employer allows leave to be borrowed from a future allowance
• an adjustment is waiting to be applied
• your leave system calculates balances in a different way

A negative figure does not automatically mean something is wrong.

If your balance is lower than expected, check how your employer records booked leave, carry-over and adjustments.

Running holiday balance example

A simple running balance can make it easier to keep track of your leave.

Start with 120h.

Take one 7h 30m shift as leave:

120h − 7h 30m = 112h 30m

Then book another 15h. Available to book:

112h 30m − 15h = 97h 30m

So the running balance becomes 97h 30m available.

This is a useful way to check how individual bookings change your overall balance.

Common mistakes when calculating remaining holiday hours

Forgetting leave that is already booked

If you want to know what is still available to book, future bookings need to be accounted for.

Subtracting booked leave twice

Some employer systems already deduct booked leave from the displayed balance.

Check what the number on your system represents before subtracting it again.

Mixing decimal hours with hours and minutes

0.50 hours means 30 minutes, not 50 minutes.

Keep both figures in the same format before subtracting them.

Confusing remaining entitlement with available-to-book leave

These can be different figures.

Remaining entitlement may include leave that is already allocated to future bookings.

Using this calculation to work out statutory entitlement

This page assumes you already know your holiday allowance.

It does not calculate the amount of annual leave you should legally receive.

This is not an annual leave entitlement calculator

Hundred Hour helps you understand and work with a leave balance you already have.

For example, if your employer tells you that your annual leave allowance is 180 hours, you can use this page to work out what remains after taken and booked leave.

If you need to check how much holiday entitlement you should receive in the first place, use official GOV.UK guidance or speak to your employer.