1 year
The first one. A short, personal thank-you from their manager means more now than it ever will again.
Free tools · Work anniversary calculator
Work anniversary calculator
Exact years, months and days of service from any start date, and when the next anniversary falls. Or paste your whole team and see every upcoming work anniversary in date order.
Free, and nothing leaves your browser.
One person
0years0months0days
Your whole team
One person per line: name, start date, and an email if you want the letters file. Paste straight from Excel or Google Sheets.
| Name | Started | Next anniversary | Years | In |
|---|
Work anniversary milestones
3 years
Often the point people decide whether to stay. Name something they have built or changed.
5 years
A real milestone. Gather a line from each colleague, or a voice note from the team.
10 years
A decade. Look back at what the company looked like when they joined, and thank them for the difference.
15 and 20 years
Rare and worth marking properly, with leadership signing the letter as well as their own team.
25 years
A career. Ask people who worked with them over the years to add a memory.
Questions people ask
How is the length of service calculated?
From the start date to today (or a date you choose), counted in whole years, then whole months, then days, the same way you would count a birthday. A start date of March 31 has its monthly mark on the last day of shorter months.
Can I calculate work anniversaries for my whole team?
Yes. Paste a list of names and start dates, and you get every upcoming anniversary in date order, with the number of years each one marks. Download it as a spreadsheet for Excel or Google Sheets.
Which work anniversaries are milestones?
Most companies mark 1, 5, 10, 15, 20 and 25 years, and many celebrate every year in the first five. The calculator flags the milestone years so you can plan something special.
Is my data sent anywhere?
No. Every calculation runs in your browser, and nothing you type or paste is sent to us or stored.
Can it send the anniversary messages?
Download "Anniversary letters for GreetSpark" and upload it on the spreadsheet send page. Each person gets a letter on their anniversary at 6 am, with the right number of years in it.
Every anniversary, on the day
Upload the letters file once and every work anniversary letter arrives on the day, with the right number of years. Three letters a month are free.
Upload a team list