How to Add 90 Days to a Date in Google Sheets
Learn how to add 90 days to a date in Google Sheets with simple formulas, examples, and edge-case tips for reliable date arithmetic in spreadsheets used for planning, budgeting, and project timelines.
To add 90 days to a date in Google Sheets, treat the date as a serial number and simply add 90. Use =A2+90 for an exact 90-day addition, which preserves date formatting. If you need three calendar months instead of 90 days, use =EDATE(A2,3). For dates stored as text, wrap with DATEVALUE before arithmetic to ensure reliability.
Understanding date arithmetic in Google Sheets
Dates in Google Sheets are stored as sequential numbers representing days since a base date. This numeric representation allows straightforward arithmetic on date values. To add 90 days to a date, you can simply write a formula like =A2+90. This approach yields a new date 90 days after the input date and keeps the value as a true date for formatting and further calculations. If you instead need to add three calendar months, you should use =EDATE(A2, 3). Note the distinction: +90 adds fixed days, while EDATE moves by calendar months, which can land on a different day-of-month if a month has fewer days.
=A2+90=DATE(2026,1,15) + 90=EDATE(A2,3)Practical workbook setup: date column, output column, and validation
In a typical sheet, you’ll have a Start Date in column A and a calculated outcome in column B. Start by ensuring A contains real dates (not text). Then, in B2, enter the 90-day formula and copy down. This section shows a small dataset and how the formula propagates down the column.
A1: Start Date
A2: 2026-03-05
A3: 2026-12-15B2: =A2+90
B3: =A3+90To handle larger datasets, use an array formula to auto-fill:
B2: =ARRAYFORMULA(IF(A2:A="",, A2:A + 90))Handling dates stored as text and locale considerations
Sometimes dates arrive as text or in a locale-specific format (e.g., dd/mm/yyyy). In such cases, convert to a true date before adding days. DATEVALUE parses a date string according to the sheet’s locale. If your input uses slashes in a non-default format, you may need to normalize first with SUBSTITUTE. These strategies prevent #VALUE! errors when performing 90-day additions.
A2: "03/05/2026" (text)
B2: =DATEVALUE(A2) + 90A2: "05-03-2026" (text with dashes)
B2: =DATEVALUE(SUBSTITUTE(A2, "-", "/")) + 90If the date is still not recognized, wrap with IFERROR to display a friendly message:
B2: =IFERROR(DATEVALUE(A2) + 90, "Invalid date")Advanced: array formulas and automation
Array formulas let you apply 90-day logic to entire columns without dragging. Use ARRAYFORMULA to compute downstream dates for all rows with a single formula, and you can pair it with 3-month equivalents as needed. This is especially helpful for templates and dashboards that pull from dynamic datasets.
B2: =ARRAYFORMULA(IF(A2:A="",, A2:A + 90))C2: =ARRAYFORMULA(IF(A2:A="",, EDATE(A2:A, 3)))For large sheets, avoid per-row recalculation by placing these formulas in header rows and limiting range references to improve performance.
Real-world template patterns and validation tips
In production templates, it’s common to compute both a 90-day date and a 3-month date side-by-side for comparison. You can encapsulate this in a small template with a header and auto-fill logic:
D1: 90_days
E1: 3_months
D2: =A2+90
E2: =EDATE(A2,3)If you’re distributing the sheet for teammates, consider validating inputs with a simple check: confirm the input cell is a valid date before arithmetic. A robust approach uses ISNUMBER to guard the addition:
F2: =IF(ISNUMBER(A2), A2+90, "Invalid date")Steps
Estimated time: 15-25 minutes
- 1
Open your sheet and verify date column
Open the Google Sheets document and locate the date column. Ensure the dates are true date values, not text strings, to enable reliable arithmetic like +90.
Tip: If unsure, format the date column as Date and re-enter a sample date. - 2
Choose the output column
Decide where results should appear (e.g., column B next to the input dates). Label the header clearly (e.g., 'Date + 90 days').
Tip: Avoid overwriting the input column to preserve original data. - 3
Enter the 90-day formula
In the first output cell, enter the 90-day formula. Example: =A2+90. This adds exactly 90 days to the input date.
Tip: If the date includes time, consider adding 90/24 to preserve hours. - 4
Fill the formula down
Drag the fill handle or use an array formula to propagate down the results for the data range.
Tip: Use Ctrl+D or Cmd+D for quick vertical filling. - 5
Format as date and validate
Format the output cells as Date and validate several rows across month/year boundaries to ensure correct handling of leap years and month ends.
Tip: Double-check end-of-month edge cases (e.g., adding 90 days to Jan 31st). - 6
Optional: automate with ARRAYFORMULA
If you want full column automation, replace per-row formulas with an array version like =ARRAYFORMULA(IF(A2:A="",, A2:A + 90)).
Tip: Place array formulas in the header row to apply down the entire column.
Prerequisites
Required
- Google account with access to Google SheetsRequired
- Google Sheets opened in a modern browserRequired
- Basic knowledge of Google Sheets formulasRequired
Optional
- Understanding of locale-specific date formatsOptional
Keyboard Shortcuts
| Action | Shortcut |
|---|---|
| CopyCopy cell or formula | Ctrl+C |
| PastePaste into target cell | Ctrl+V |
| Fill downFill formula down a column | Ctrl+D |
| UndoUndo last action | Ctrl+Z |
FAQ
What is the difference between adding 90 days and adding 3 calendar months in Google Sheets?
Adding 90 days adds a fixed number of days, regardless of month lengths. Adding 3 calendar months moves forward by the same day of the month, which can land on a different date if a month has fewer days. Use =A2+90 for exact days and =EDATE(A2,3) for months.
You can choose between fixed days or calendar months depending on your needs; 90 days is a constant, while three months follows calendar months.
Can I apply the 90-day rule to an entire column without dragging formulas?
Yes. Use an array formula such as =ARRAYFORMULA(IF(A2:A="",, A2:A + 90)) to compute results for every date in column A without manual filling.
You can auto-calculate the whole column with an array formula.
What if the start date is stored as text?
Convert with DATEVALUE before adding days, e.g., =DATEVALUE(A2) + 90. If the text uses slashes, you may need to adjust with SUBSTITUTE depending on locale.
Convert text dates with DATEVALUE to apply 90-day arithmetic.
Do leap years affect the 90-day addition?
No. Adding 90 days uses absolute day counts and automatically accounts for leap days; the result remains consistent across years.
Leap years don’t change the 90-day calculation.
Why might =A2+90 return an error?
If A2 isn’t a true date (e.g., text not converted or a non-date string), Google Sheets cannot add 90 days. Convert inputs to dates first or wrap with DATEVALUE.
Make sure inputs are real dates before arithmetic.
The Essentials
- Add 90 days with =A2+90
- Use =EDATE(A2,3) for calendar months, not fixed days
- Convert text dates with DATEVALUE before arithmetic
- ARRAYFORMULA simplifies large datasets