How PTO Accrual Works: Methods, Formulas and Examples

“How much PTO do I have?” sounds like a simple question. With accrual, the honest answer is often “it depends which day you ask”. Balances grow a little every paycheck, stop at a cap, reset or roll over at the end of the year, and pause during unpaid leave. Get one of those rules wrong and every balance in the company drifts a little further from the truth.

This guide explains how PTO accrual works: the main accrual methods, the formulas behind them, worked examples for salaried, hourly and part-time staff, and the caps, carryover rules and legal requirements that decide what happens to the balance over time.

What is PTO accrual?

PTO accrual is a way of granting paid time off in small amounts over time. Instead of putting 15 days into an employee’s balance on 1 January, the company adds a fraction of a day every pay period. By the end of the year the employee has earned the full 15 days.

The term is most common in the United States, where PTO (paid time off) often combines vacation, personal days and sometimes sick leave into one balance. The same idea exists everywhere, though. In the UK, for example, workers in their first year of employment build up annual leave at one-twelfth of their yearly entitlement each month.

Accrual vs front-loading

The alternative to accrual is front-loading (also called lump-sum or up-front PTO): the full yearly allowance lands in the balance at the start of the year. Both are common, and the right choice depends on your team.

A popular middle ground is to front-load after a probation period, or to accrue but let people borrow a limited amount ahead of what they have earned. More on that in the edge cases below.

5 common PTO accrual methods

1. Per pay period

The yearly allowance is split evenly across every paycheck. This is the most common method for salaried employees, because it lines up with payroll. The number of pay periods depends on how often you pay: 52 for weekly, 26 for every two weeks (biweekly), 24 for twice a month (semimonthly) and 12 for monthly.

2. Per hour worked

Employees earn a fixed amount of PTO for every hour they work, such as 1 hour of PTO for every 30 hours worked. This suits hourly, part-time and seasonal staff, because PTO grows in step with the hours they actually put in. It is also how many US state and city paid sick leave laws define their minimum.

3. Monthly

PTO is added once a month, regardless of payroll. It is easy to explain (“you earn 1.25 days a month”) and common outside the US, where most people are paid monthly anyway.

4. Annually, on an anniversary or fixed date

The full year’s PTO is granted once a year, either on the employee’s work anniversary or on a fixed date like 1 January. Strictly speaking this is front-loading, but some policies describe it as “accruing annually”, particularly when the amount depends on the previous year’s service.

5. Tenure-based tiers

Any of the methods above can increase with length of service. A typical schedule looks like this:

Decide whether the new rate starts on the anniversary itself or at the start of the next pay period or leave year. Starting on the anniversary is fairer; starting at the next period is easier to run.

How to calculate PTO accrual

Every accrual method comes down to one of two formulas. Work in hours if your payroll does; convert to days at the end if that is how people think about their time off.

Per pay period

PTO per pay period = annual PTO ÷ pay periods per year

Per hour worked

Accrual rate = annual PTO hours ÷ annual hours worked

PTO earned = hours worked × accrual rate

A full-time year is usually counted as 2,080 hours (40 hours × 52 weeks). Some employers use 1,950 (37.5 × 52) or subtract public holidays first; pick one and use it consistently.

To find someone’s balance on any date, add up what they have accrued so far, add anything carried over from last year, and subtract what they have taken:

Balance = carried over + accrued to date − PTO taken

Our PTO accrual calculator does all of this for you, including caps, and projects the balance to any date.

PTO accrual examples

Salaried employee paid biweekly

Maya gets 15 days (120 hours) of PTO a year and is paid every two weeks.

• Per pay period: 120 ÷ 26 = 4.62 hours
• After 10 pay periods: 10 × 4.62 = 46.2 hours, or about 5.8 days

If Maya took a 3-day (24-hour) trip in April, her balance after those 10 pay periods is 46.2 − 24 = 22.2 hours.

Hourly employee earning per hour worked

Sam earns 1 hour of PTO for every 30 hours worked. The rate is 1 ÷ 30 = 0.0333 hours per hour.

• A 40-hour week: 40 × 0.0333 = 1.33 hours
• A 22-hour week: 22 × 0.0333 = 0.73 hours
• A full year at 40 hours a week: 2,080 ÷ 30 = 69.3 hours, or about 8.7 days

Part-time employee on a monthly accrual

Your full-time allowance is 25 days a year, accrued monthly. Alex works three days a week, so their allowance is pro-rated:

• Pro-rated allowance: 25 × (3 ÷ 5) = 15 days
• Per month: 15 ÷ 12 = 1.25 days

For part-time staff, track balances in hours or in the days they actually work. A day off for Alex is one of their three working days, not a fifth of a week. The pro-rata holiday calculator handles other working patterns.

New starter joining mid-year

One advantage of accrual is that new starters are handled automatically. Someone who joins on 1 July on a 20-day monthly accrual earns 20 ÷ 12 = 1.67 days a month and has 10 days by 31 December. No separate pro-rata calculation is needed.

Accrual caps and carryover

Without limits, an employee who never takes time off builds up a bigger balance every year. That is bad for them, because they are not resting, and bad for the company, because unused PTO is a liability that may have to be paid out. Two rules keep it in check.

Accrual cap

An accrual cap is the most PTO someone can hold at once. When the balance reaches it, accrual stops until they take some time off. Nothing earned is taken away; they simply stop earning more. Caps are often set at 1.5 to 2 times the annual allowance, so someone on 15 days might be capped at 30.

Carryover limit

A carryover limit decides how much unused PTO moves into the next year. Anything above it is lost at the year-end reset (where the law allows that). A common rule is up to five days, to be used by the end of March.

Use it or lose it

A “use it or lose it” policy is a carryover limit of zero: any PTO not taken by the end of the year disappears. It encourages people to take time off, but it is restricted or banned in some places (see what the law says). Where it isn’t allowed, an accrual cap is usually the safer way to limit balances.

Edge cases your accrual policy should cover

• Waiting periods. Some employers start accrual on day one but only let people use PTO after 60 or 90 days. Check local law: some paid sick leave laws limit how long the wait can be.
• Negative balances. Decide whether people can borrow PTO they haven’t earned yet, how much, and what happens if they leave while in the negative. Deducting it from final pay is only allowed in some places and usually needs written agreement.
• Unpaid leave and leaves of absence. Say whether PTO accrues during unpaid leave, parental leave or a sabbatical. Many policies pause accrual during unpaid leave, but statutory leave can have its own rules.
• Overtime. For per-hour accrual, say whether overtime hours count. Most policies count them, some cap the hours that earn PTO at 40 a week.
• PTO hours. Does time off itself count as hours worked for accrual? Usually it does for salaried staff, who keep accruing while on vacation, but not always for hourly staff.
• Rounding. Accrual rates rarely come out to whole numbers. Keep at least two decimal places in the balance and only round what you show to people.
• Rate changes. When someone moves to a new tier or changes hours, apply the new rate from a clear date and keep what they already accrued at the old rate.

What the law says about PTO accrual

PTO rules vary a lot between countries and, in the US, between states. This section is a starting point, not legal advice. Check official guidance where your employees work.

United States

There is no federal requirement to offer paid vacation, so accrual methods, caps and carryover are mostly up to the employer. State law steps in at two points:

• Forfeiture. California, Montana and Nebraska treat earned vacation as wages that can’t be taken away, so “use it or lose it” policies aren’t allowed there. Accrual caps generally are, because they stop new PTO being earned rather than removing PTO already earned.
• Payout. A number of states, including California, Colorado, Illinois and Massachusetts, require accrued, unused vacation to be paid out when someone leaves. Our PTO payout calculator shows what that is worth.

Paid sick leave is different. Many states and cities require it, and they usually set a minimum accrual rate, often 1 hour for every 30 hours worked, along with rules on caps, carryover and when new employees can start using it. If your PTO policy combines vacation and sick time, it has to meet those rules too.

United Kingdom

Most workers are entitled to 5.6 weeks of paid holiday a year. In the first year of employment, leave builds up at one-twelfth of the yearly entitlement at the start of each month. Since April 2024, holiday for irregular-hours and part-year workers accrues at 12.07% of the hours they work each pay period. The holiday entitlement calculator covers the details.

European Union

The Working Time Directive guarantees at least four weeks of paid annual leave, and many countries give more. EU case law also limits when unused leave can be lost: generally only if the employer gave the employee a real chance to take it and warned them it would expire.

Common PTO accrual mistakes

• Using the wrong number of pay periods. Biweekly is 26 periods, not 24. Mixing them up gives every employee the wrong rate.
• Mixing hours and days. Accrue in one unit and convert only for display. Converting back and forth creates rounding drift.
• Forgetting the cap. If the cap only lives in the policy document, balances keep growing past it in the spreadsheet.
• Confusing caps with carryover. A cap applies all year. Carryover applies once, at year end. Write down both.
• Ignoring state law. A use-it-or-lose-it rule that is fine in Texas can be unlawful in California.
• Not showing people their balance. If employees can’t see what they have accrued, they either don’t book time off or book time they don’t have.

Whichever method you choose, write it into your leave policy. Our guide on how to write a leave policy includes a template with an accrual section you can copy, and how to track employee leave covers the balance formulas for a spreadsheet.

The bottom line

PTO accrual spreads time off across the year: divide the annual allowance by the number of pay periods, or by the hours in a working year, and add that to each person’s balance as they go. It handles new starters and hourly staff neatly and protects you if someone leaves early, at the cost of balances that change every paycheck. Pair it with a clear cap and carryover rule, check them against the law where your people work, and make sure everyone can see their balance at any time.