Date & Time calculator
Calendar Calculator - Month, Weekday, and Days
Check a month calendar summary with days in month, first weekday, last date, and calendar row count.
FormulaDays in month = last day of selected month; calendar rows = ceil((first weekday offset + days) / 7)
Formula
Calendar month method
Calendar summaries use the browser's Gregorian calendar handling. Confirm legal, payroll, school, and filing deadlines with the relevant authority.
Days in month = last day of selected month; calendar rows = ceil((first weekday offset + days) / 7)
July 2026 has 31 days, starts on Wednesday, and spans five Sunday-first calendar rows.
FAQ7 common questions for this calculator.
FAQs
What does the Calendar Calculator show?+
It shows days in the selected month, the first weekday, the last date, and how many Sunday-first calendar rows the month spans.
Does it show ISO week numbers?+
No. Use the Week Number Calculator for ISO-style week numbers.
Can I check leap-year February?+
Yes. Choose February and a leap year to see 29 days.
How does the Calendar Calculator calculate the result?+
For the Calendar Calculator, it uses the Calendar month method: Days in month = last day of selected month; calendar rows = ceil((first weekday offset + days) / 7). July 2026 has 31 days, starts on Wednesday, and spans five Sunday-first calendar rows.
What information do I need to use the Calendar Calculator?+
For the Calendar Calculator, enter the relevant dates, times, timezone, or calendar settings requested by the form. Exact dates matter because month lengths, leap years, and boundary days can change the result.
How accurate is the Calendar Calculator?+
Calendar Calculator is accurate for the values and assumptions entered on this page. It uses the Calendar month method. Recheck the inputs before relying on the estimate.
What should I check before using the Calendar Calculator result?+
For the Calendar Calculator, check the date and time fields, date format, timezone, daylight-saving changes, inclusive or exclusive endpoints, and whether weekends or holidays should count.
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Date & Time guide
How to use the Calendar Calculator
Check a month calendar summary with days in month, first weekday, last date, and calendar row count. The page also explains the calendar month method and shows a practical example: July 2026 has 31 days, starts on Wednesday, and spans five Sunday-first calendar rows.
- 1
Enter your details
Enter days in month, first weekday, last date, and calendar row count, then complete any other fields shown in the calculator.
- 2
Check the calculation
Review the result alongside the calendar month method: Days in month = last day of selected month; calendar rows = ceil((first weekday offset + days) / 7).
- 3
Compare scenarios
Change one or more inputs to see how they affect the calendar Calculator result before you use the estimate.