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Date & Time Calculators

Calendar Calculator

View a monthly calendar with weekday details and ISO week numbers.

Free foreverRuns in your browserNo sign-up

Selected month

January 2026

Thursday
First weekday
31
Number of days
Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
29
30
31
1
2
3
4
2
5
6
7
8
9
10
11
3
12
13
14
15
16
17
18
4
19
20
21
22
23
24
25
5
26
27
28
29
30
31
1
6
2
3
4
5
6
7
8

Weeks run Monday through Sunday. Faded dates belong to adjacent months.

About the Calendar Calculator

The Calendar Calculator builds a complete Monday-to-Sunday calendar for any Gregorian month from year 1 through 9999. Choose a month and year or move one month at a time with the navigation controls.

The summary identifies the weekday on which the month begins and the total number of days. The grid includes faded dates from adjacent months so every displayed week remains complete.

Optional ISO-8601 week numbers appear beside each row. ISO weeks begin on Monday, and week 1 is the week containing January 4, so New Year boundaries can show week 52, 53 or 1.

When the selected month contains today's local date, that date is highlighted. Calendar generation uses date-only UTC arithmetic so timezone changes cannot shift grid dates.

Key features

  • Month and year selection
  • Previous and next month navigation
  • Monday-first six-week calendar grid
  • First weekday and month-length summary
  • Optional ISO week numbers
  • Current-date highlighting

How to use

  1. 1Choose a month and enter a year from 1 through 9999.
  2. 2Use Previous and Next to move one month at a time, or Go to today to return to the current month.
  3. 3Toggle ISO week numbers depending on whether you need the week-of-year column.
  4. 4Read the first weekday, number of days and complete calendar grid.

Frequently asked questions

Which day starts the calendar week?
Monday is the first day of each displayed week, matching the ISO-8601 week-number system.
Why are some dates faded?
They belong to the previous or next month and are shown to complete the Monday-through-Sunday calendar rows.
What are ISO week numbers?
ISO week numbers label Monday-through-Sunday weeks. Week 1 is the week containing January 4, and an ISO year can contain 52 or 53 weeks.
Does the calendar handle leap years?
Yes. Gregorian leap-year rules are applied, so February contains 29 days in leap years and 28 otherwise.
Which years are supported?
The calculator supports Gregorian calendar years from 1 through 9999.

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