Calendar Calculator
A Full Month Grid, Starting Wherever You Prefer
A month's calendar grid depends on one small fact that's easy to get wrong from memory: which day of the week the 1st falls on. Everything else — where the rows break, how many blank cells pad the start and end — follows from that single anchor point plus the number of days in the month. This calculator builds the grid for any month and year, and lets the week start on either Sunday or Monday, since conventions differ by region.
The Logic
Days in Month = 28, 29, 30, or 31 depending on month and leap year status
Starting Weekday = day of week that the 1st of the month falls on
Starting Weekday = day of week that the 1st of the month falls on
A Worked Example
July 2026:
| Metric | Value |
|---|---|
| Days in month | 31 |
| 1st of the month falls on | Wednesday |
| Leap year | No |
Where This Calculation Matters
- Building custom calendars or schedules — generating a reference grid for a specific month without needing to flip through a physical calendar.
- Regional formatting — Sunday-start weeks are standard in the U.S.; most of Europe and much of the rest of the world uses Monday-start, and getting this wrong misaligns every row.
- Planning around month length — quickly confirming whether a given month has 28, 29, 30, or 31 days when setting up recurring monthly schedules.
How to Use This Calculator
- Select the month.
- Enter the year.
- Choose whether the week should start on Sunday or Monday.
- Select Calculate to see the full month grid, day count, starting weekday, and leap year status.
Related Calculations
To check whether a given year is a leap year on its own, use the Leap Year Calculator. For the day of the week of any single date, see the Weekday Calculator.