Recurring plans run on a clock. Add the interval in days to the last service date and Excel hands you the next appointment — no calendar counting.
June 1 plus a 90-day cycle lands on August 30. Format the result as a date and it is ready to drop on the schedule.
The example
Each account has a last-service date and a cycle length in days.
| A | B | C | |
|---|---|---|---|
| 1 | Last service | Interval (days) | Next service |
| 2 | Jun 1, 2026 | 90 | Aug 30, 2026 |
| 3 | May 15, 2026 | 30 | Jun 14, 2026 |
| 4 | Jul 1, 2026 | 60 | Aug 30, 2026 |
The formula
Because dates are stored as numbers, you can add days directly:
How it works
Excel keeps every date as a serial number of days, so arithmetic just works:
A2holds the last service date.B2is the cycle length in days for that plan.- Adding them moves the date forward by exactly that many days; format the cell as a date to read it.
Need whole months instead of days? Use =EDATE(A2,3) to jump exactly three months and keep the day-of-month aligned.
Try it: interactive demo
Pick a last-service date and an interval in days.
Variations
Skip weekends
If crews only work weekdays, land the next visit on a business day with WORKDAY.
Monthly cycle
For a true monthly plan, add months rather than days so the date does not drift.
Pitfalls & errors
If the last-service cell holds text that looks like a date, the math fails. Make sure it is a real date (right-aligned by default).
A new result cell may show a serial number like 46264. Format it as a date to display it properly.
Practice workbook
Frequently asked questions
Why does my result show a number instead of a date?
How do I keep visits on weekdays only?
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