Length of Service Calculator

What the length of service calculator shows

Length of service is one of those numbers that sounds simple until you need it. A job application asks for years of experience. A severance clause pays a number of weeks for each year with the company. A loyalty bonus starts after five years, a notice period grows with every year, and a pension plan needs a minimum record. Counting it on your fingers works for one job with round dates. With several jobs, a few gaps, a second job on the side and dates in the middle of the month, it becomes a small puzzle, and two people who do the arithmetic by hand rarely get the same answer.

This calculator does that arithmetic for you. You enter each period of work with its start and end dates, and it returns your total length of service in years, months and days, the total in calendar days and the number of separate periods once overlapping and back-to-back jobs are joined. When two jobs ran at the same time, it counts that time once and tells you how many days of overlap it set aside. When the leftover days add up to 30 or more, it also shows what the total would be if every 30 days were counted as a month, clearly labelled as a convention.

The result is a duration, not a legal entitlement. The calculator knows the calendar; it does not know your contract, your employer's policy or the law of your country. Those decide which periods count, how breaks are treated and how partial years are rounded, and this guide shows where they usually differ. Everything runs in your browser, and nothing you enter is sent anywhere.

How to use it

The Your numbers panel has one field, Periods of work: a list of rows named Period 1, Period 2 and so on. Each row has three parts.

1. Start. The first day of the period, usually your first day of employment. The date picker accepts any day from 1 January 1950 to today.
2. End. The last day of the period, usually your last day of employment. Both dates are part of the period.
3. Until today. A box for a job you still have. When it is ticked, the End field is switched off and shows today's date.

When you open the calculator, it shows a single job that started on 1 September ten years ago and is still running. On 22 October 2026 that is 1 September 2016 to today: 10 y 1 m 22 d, or 3,704 calendar days. Replace the dates with your own. Add period adds a new row, already filled with the year just before your earliest period, so that it never overlaps the rows you have; correct its dates to the real ones. You can enter up to 30 periods. The button next to a row removes it, and the last remaining row cannot be removed.

The order of the rows does not matter, because the calculator sorts the periods by date before it counts them. If a row has a start after its end, an incomplete date or a date outside the allowed range, a hint appears under it and that period is left out. A notice above the results says how many periods were left out, so a typo never changes your total silently.

Below the inputs, How it's calculated lists every rule the calculator applies, in the same words as this guide.

Entering your dates from your records

Good sources are your contracts, termination letters, final payslips or an official employment history. A few habits save time:

• A promotion or a change of role with the same employer does not interrupt your service. Enter one period from your first day to your last day there.
• A move to a new employer with no gap can be entered as two rows. If the new job starts the day after the old one ends, the calculator joins them into one period.
• A second job held at the same time goes in its own row with its own dates. The time it shares with your main job is counted once, but any part of it that falls into a gap between main jobs adds to the total.
• If you only know the month, use the first day of the month as a start and the last day of the month as an end. The error is at most a month at each end, and the Periods table shows you exactly what was counted.

When you have entered everything, open the Periods tab. It shows how the calculator joined your rows, which makes a wrong year or a swapped date easy to spot.

Reading the results

The headline, Total length of service, shows years, months and days in short form, such as 10 y 1 m 22 d. Zero parts are left out, so one full year shows as 1 y and 43 leftover days as 43 d. Up to four figures sit below it:

• Calendar days: the total number of days covered by your periods, with overlaps counted once;
• Separate periods: how many periods remain after overlapping and back-to-back rows are joined;
• Overlap counted once: the days that two or more rows shared, shown only when there are any;
• With 30-day months (convention): the total if every 30 leftover days were a month, shown only when the leftover days reach 30.

A notice repeats the overlap in words when there is one. The Periods tab lists the joined periods with their start, end, length and number of days, and a job you still have ends with Today. Pin to compare keeps the current result while you change the dates, and the headline then shows the difference in days, which is the quickest way to see what one extra job or one corrected date changes. PDF saves your periods, the figures and the table, and Reset brings back the default row. On phones and tablets the result sits in a panel at the bottom of the screen, and Details opens the figures and the table.

How the calculation works

The calculator counts length of service in three steps, and each of them can be checked by hand.

1. Join: periods that overlap or follow each other day by day become one period
2. Measure each period: from the start date to the end date, both included,
   in full years, full months and the days that remain
3. Add up: years + years, months + months (12 months = 1 year), days + days

A calendar month is the time from a given day of one month to the same day of the next month. A period from 15 March to 14 April inclusive is exactly one month, although it has 31 days, and a period from 15 February to 14 March 2023 is also exactly one month, with only 28 days. That is why months of service cannot be found by dividing days by 30: the same number of days can be a full month in one part of the year and fall short in another.

When the start day does not exist in the target month, the calculator takes the last day of that month. A period from 31 January to 28 February 2024 inclusive has 29 days, and the calculator shows it as 1 month: one month after 31 January is 29 February, which is exactly the first day after the period. Many HR systems and date tools count the same way.

In the third step, 12 months become one year, because that is an exact equality. Days from different periods are simply added, even when there are more than 30 of them, which the next section explains. Next to years, months and days, the calculator also shows the total number of calendar days, which needs no convention at all: it is the end date minus the start date plus one day, summed over the joined periods.

Leap years are handled by the calendar itself. 2020 had 366 days, so a period from 1 January to 31 December 2020 is 1 year and 366 days, while the same dates in 2015 give 1 year and 365 days. The years, months and days are the same; only the day count differs.

Calendar months versus 30-day months

Most disagreements between two calculations of length of service come from leftover days. The calculator adds the days from different periods as days and does not turn them into months, even when they add up to more than 30. Two short jobs, from 20 January to 10 February 2019 and from 5 to 25 May 2019, last 22 and 21 days. Neither reaches a full calendar month, so the total is 43 days.

Many people, and some payroll and HR tools, count differently: they take 30 days as a month and get 1 month 13 days. That convention is common, but it is a convention, not a property of the calendar, and two tools that use it can still disagree on where the leftover days come from. The calculator therefore keeps the calendar result as its headline and shows the 30-day reading as a separate figure, With 30-day months (convention), whenever the leftover days reach 30. If the rule you are checking uses 30-day months, you see both readings side by side and can use the one it asks for.

The table shows how the same dates read under the two methods.

The last column divides the days by 30, the way a pure 30-day count would, and the last row shows why such counts drift over long periods: a year has more than twelve 30-day months in it. The calculator's own 30-day figure avoids that drift, because it converts only the leftover days and keeps full calendar months and years as they are. For comparing two versions of your dates, the most reliable figure is Calendar days. It is exact and does not depend on how months are counted.

Overlaps, back-to-back jobs and gaps

Length of service is time, not the number of jobs. If you held two jobs at once for six months, those six months add six months of service, not a year. The calculator joins every set of overlapping periods into one and reports the days it set aside in the Overlap counted once figure and in a notice under the results.

Back-to-back periods, where the next one starts the day after the previous one ends, are joined too. This matters when you move to a new role or a new employer without a break: two rows give the same result as one, and no leftover days are lost because the job was split. A job from 15 January to 31 March 2010 followed by one from 1 to 14 April 2010 is exactly 3 months, or 90 days, not 2 months 17 days plus 14 days.

Gaps between jobs are not counted, and they keep the periods apart. Two weeks between leaving one job and starting the next add nothing to the total, and the Separate periods figure shows that there are two periods. Even one missing day separates them. A job that ends on Friday and a new one that starts on Monday are two periods, because the weekend is not covered by either contract, unless the new contract's start date is the Saturday.

Whether a gap matters beyond the total depends on the rule you are checking. Some rules only add up time, wherever it falls. Others need continuous service with one employer, and a break can restart the count from zero. The Separate periods figure tells you at a glance whether your record is one stretch or several.

Total days and other units

The calendar days figure is the bridge to every other unit. Some rules count weeks, some count decimal years, some count full months only. The table converts the default example, 1 September 2016 to 22 October 2026, into the units you are most likely to meet.

Two cautions apply. Full years and full months always round down: 10 years 11 months is still 10 full years, and a rule that pays per full year pays for ten. And decimal years are an approximation that can differ in the second decimal from one tool to another, depending on whether it divides by 365, 365.25 or the actual days in each year. When a rule names a unit, convert from the calendar days or from the headline in exactly the way it describes.

Worked examples

The figures below are calculator results for the dates shown. Examples that end on today's date were calculated on 22 October 2026 and grow by a day each day after that.

Where length of service matters

Length of service feeds into many decisions, and each of them comes with its own rules about which time counts. The calculator gives you the duration; the rule decides what the duration is worth. Some common places it appears:

• Notice periods. Many countries set a minimum notice that grows with service, and contracts can give more.
• Redundancy and severance pay. Statutory or contractual payments are often a number of weeks' pay for each year of service.
• Leave and benefits. Some rights start only after a qualifying period with one employer, and some leave entitlements grow with seniority.
• Seniority pay and bonuses. Collective agreements and company policies often add pay steps after a number of years.
• Pensions. Public and workplace pensions use a contribution record, which can be counted in months with contributions, in earnings credits or in calendar time.

Two well-documented examples show how much the rules can add to a plain duration.

In the United Kingdom, the Employment Rights Act 1996 decides week by week whether employment counts and whether separate periods form one period of continuous employment. A week that does not count breaks continuity, except in cases the Act lists, such as sickness, a temporary cessation of work or an arrangement under which you are still regarded as employed. Where the length has to be computed, it is counted in months and years of twelve months, from the day you started work. According to GOV.UK, the statutory minimum notice period is at least one week after one month of employment, one week for each year between 2 and 12 years, and 12 weeks after 12 years. Statutory redundancy pay needs at least 2 years with your current employer and counts each full year of service, capped at 20 years.

In the United States, to qualify for job-protected leave under the Family and Medical Leave Act, an employee must have worked for a covered employer for at least 12 months and have at least 1,250 hours of service in the 12 months before the leave, among other conditions. The regulation says the 12 months need not be consecutive, that 52 weeks count as 12 months, and that employment before a break of seven years or more generally need not be counted. Here the calculator's ability to add separate periods with the same employer is exactly what the rule asks for, while the hours test has to be checked separately.

The same pattern holds almost everywhere: a rule starts from the calendar duration that this calculator shows, then decides which periods count, whether breaks reset the count and how partial years are rounded. When a rule uses only full years, take the years from the headline. When it counts weeks, divide the calendar days by 7. When it needs unbroken service with one employer, enter only the periods with that employer and check that the Separate periods figure is 1.

If you are estimating a Ukrainian state pension, the Ukraine pension calculator asks for your insurance record in years and months. Ukraine's pension insurance counts months with contributions from 2004 on, so the record in your official statement can differ from the calendar duration shown here.

Choosing the right dates

The calculator is only as accurate as the dates you give it, and most differences between two calculations come from different dates, not different arithmetic. A few choices come up again and again.

Start date. Use the first day you were employed under the contract, normally the start date in your contract or offer letter. A probation period is usually part of the employment, so it belongs in the period. If your employer counts service from a later date, for example from the end of probation, a transfer or a change of contract, the rule you are checking should say so.

End date. Use the last day of employment, which is not always the last day you were at work. Paid notice that you were not asked to work, or garden leave, may keep the employment going until a later date. Use the date on your termination letter or final payslip.

Leave and absences. Paid leave and short sickness usually stay inside the period, because the contract continues. Long unpaid leave, a career break or a sabbatical may or may not count, depending on the rule. If a rule excludes them, split the job into two rows around the excluded time.

Self-employment and freelance work. These are not employment with an employer, but they can be experience. Enter them when you want a total of working time, and leave them out when a rule asks only for service with an employer.

What the calculator leaves out

The calculator measures time between dates. It does not know who you worked for, under what kind of contract or how many hours a week, and it applies no law, contract or policy.

Dates before 1 January 1950 and after today are not accepted, so the calculator cannot show your service on a future date. Enter today as the end and add the remaining time yourself.

The result is not legal, tax or financial advice and does not replace a statement from an employer, a pension provider or a public authority. When your service affects money you will receive, ask the body that decides for its own figure and use the calculator to check it.

Common mistakes

• Entering the day after you left as the end date. The end date is your last day of employment. The day after adds a day to every period and can make back-to-back jobs look as if they overlap.
• Adding up job lengths by hand. Two jobs that ran at the same time do not double your service. Enter both and let the calculator count the shared time once.
• Turning leftover days into months. 43 days is not 1 month 13 days unless a rule says 30 days make a month. The calendar method and the 30-day reading are both shown, so pick the one your rule uses.
• Splitting one job by mistake. A one-day gap between two rows keeps them apart. A job from 7 April 2014 to 30 November 2019 and another from 2 December 2019 to 17 February 2023 give 8 y 9 m 40 d in two periods, while a start on 1 December gives 8 y 10 m 11 d in one.
• Leaving a period out without noticing. A row with a start after its end or an incomplete date is skipped, and a notice above the results tells you so. Read the notices before you copy the total.
• Treating years of service as an entitlement. Notice, severance, leave and pensions follow their own rules. The duration is the starting point, not the answer.
• Comparing results without the day count. Two tools can show different years and months for the same dates. Compare Calendar days first, then the method.

Next steps

Once you know how long you have worked, the next question is usually what that time means for your money. If a job is ending, a severance payment or a final paycheck is a good moment to check your safety cushion with the emergency fund calculator and the basics article on building an emergency fund.

Years of service are also years of saving. The compound interest calculator shows what regular saving over the same span of time could have grown into, and the article on compound interest and the time value of money explains why the early years count most. The FIRE calculator and the article on financial independence: the capital you need and the timeline turn the question around: how many more years of work it would take until your savings could cover your spending.

If a pay rise or an indexation clause comes with seniority, the article on inflation and why money loses value helps you judge whether it keeps up with prices, and what is investing is a good start for putting part of your salary to work.