Vacation days are easy to lose track of. You know your annual allowance, you remember a holiday in spring, and you assume the rest is fine, until December arrives and you find days you cannot use or a trip you cannot take. Accrual is the reason: in many jobs you do not get all your days on January first. You earn them month by month, a twelfth of your allowance at a time, and your balance at any moment is what you have earned plus what you carried over, minus what you have used. This calculator does that maths for you.
Enter four numbers: your annual allowance, the months you have worked this year, the days you have already used, and any days carried over from last year. The tool shows how much you earn per month, how much you have earned so far, what remains right now, and what your year-end balance would be if you took no more holidays. That last number is the planning number. If it is high, book time off before the year ends; if it is low, you know a long trip needs to wait.
Here is a worked example. Your allowance is 25 days, you have worked 6 months, you have used 5 days, and you carried over none. You earn about 2.08 days per month, so after 6 months you have earned 12.5 days. Minus the 5 used, you have 7.5 days remaining right now. If you take no more, your year-end balance is 20 days, which is 25 minus 5. The gap between 7.5 now and 20 at year end is the time you will earn in the second half of the year, and it is exactly why you cannot book all 20 days in July.
Carryover rules catch many people out. Some employers let unused days roll into January, some allow only a few days, and some delete them on December 31. The tool adds your carryover in full, because it cannot know your company rule, so treat the result as a best case and check your handbook. If only five of your ten leftover days carry over, enter five, not ten. The same caution applies to probation: some contracts delay accrual for the first months, so a new starter may have earned less than the simple monthly maths suggests.
Part-time work changes the numbers but not the method. If you work three days a week, your allowance is usually scaled down in proportion, and the monthly accrual is a twelfth of that smaller allowance. Enter the scaled allowance, not the full-time figure, and the results will match your payslip. The same applies if your allowance changes mid-year after a promotion or a contract change: use the current allowance for a rough balance, and ask payroll for an exact figure before booking an expensive trip.
Planning holidays well is worth the five minutes this takes. Spread your days across the year instead of saving everything for December, when everyone else wants time off and approval is hardest. Keep a small reserve for illness, family emergencies, or a quiet week when you simply need rest. And remember that a vacation balance is not a savings account to admire: days are meant to be used, and research on rest is clear that real breaks protect health and work quality far better than carrying days forward forever.
Use this calculator whenever your plans change: after booking a holiday, after a contract change, and once in autumn, when there is still time to use days before they expire. Compare the result with your payslip or HR portal; if the numbers differ, the difference is usually a carryover rule, a probation rule, or a mid-year change, and HR can explain it in one message. Small, regular checks beat one panicked calculation in December, and they make sure your holidays happen instead of expiring.