Work Anniversary Calculator

How it works

completed service = whole calendar years, then months, then days from the start date to today · decimal years = completed years + days since the last anniversary ÷ days in that service year · next anniversary = start month/day in the first year after today

Length of service is counted by walking the calendar from your start date — whole years first, then whole months, then leftover days — so it never drifts the way a 365-day division does. The next anniversary is your start month and day in the current year, or the following year if it has already passed. The calculator also gives your service as a decimal (handy for forms that ask for 7.55 years), the total days, months and weeks, how far through the current service year you are, the date of your next 5-year milestone, and a list of upcoming anniversaries. You can count up to any date, such as a leaving date, and take out days of unpaid breaks. For HR and managers, the team mode reads a pasted list of names and start dates and returns the average and median tenure, the longest serving person and everyone’s next anniversary, soonest first. A February 29 start is celebrated on February 28 in common years.

Worked example

Starting April 1, 2019 and checked on September 15, 2026 gives 7 years, 5 months, 14 days of service — 2,724 days, or about 7.46 years. April 1 has already passed in 2026, so the next anniversary is Thursday, April 1, 2027, the 8-year mark, 198 days away. The next milestone is the 10-year mark on Sunday, April 1, 2029, 929 days away.

Frequently asked questions