Calendar Calculators

These calendar calculators answer the reference questions that come up whenever you work with dates: which weekday a date falls on, whether a year is a leap year, and where a date sits in the week-numbering system.

The Day of the Week Calculator turns any past or future date into its weekday, and What Day of the Week Was I Born does the same for your date of birth. The Leap Year Calculator checks any year against the leap-year rule, while the Week Number Calculator gives the ISO 8601 week for a date — the numbering many workplaces and schedules use.

For a wider view, the full-year pages such as Calendar 2026 lay out every month at a glance, and Days in Each Month is a quick reference for month lengths. Two short guides go deeper: what is a leap year and understanding ISO week numbers.

All Calendar Calculators (9)

Day of the Week Calculator Find out which day of the week any date falls on, past or future. Enter a date to get the weekday, the day of the year, and its ISO week number. What Day of the Week Was I Born Enter your date of birth to find out which day of the week you were born on, with the full date confirmed back to you. Leap Year Calculator Check whether any year is a leap year and see the rule behind it (divisible by 4, except centuries not divisible by 400), plus the next leap year. Week Number Calculator Find the ISO 8601 week number for today or any date, with the ISO week-year, weekday, and day of the year. Days in Each Month How many days are in each month? See all 12 months at a glance — seven have 31 days, four have 30, and February has 28 (29 in a leap year). Check any month and year. Calendar 2026 The full 2026 calendar — all twelve months with every date and weekends marked. 2026 is a common year of 365 days that begins on a Thursday. Calendar 2027 The full 2027 calendar — all twelve months with every date and weekends marked. 2027 is a common year of 365 days that begins on a Friday. Calendar 2028 The full 2028 calendar — all twelve months with every date and weekends marked. 2028 is a leap year of 366 days that begins on a Saturday. India Holiday Calendar 2026 The 2026 India holiday calendar — all 12 months with the national and gazetted public holidays marked and listed: Republic Day, Holi, the Eids, Diwali, Dussehra and more.

Frequently asked questions

How do I find what day of the week a date falls on?
Use the Day of the Week Calculator for any date, or What Day of the Week Was I Born for your birth date. Both return the weekday along with useful extras like the ISO week number.
What is an ISO week number?
ISO 8601 numbers the weeks of the year from 1, with week 1 being the week containing the first Thursday. The Week Number Calculator gives the ISO week for any date.

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