Date & time blog

Clear answers to "what was the date…" questions, plus guides to leap years, ages and calendar math.

• How to Calculate Years Ago: A Step-by-Step Guide

  Learn how to work out the exact date any number of years ago by hand, including the February 29 rule and how to find the weekday.

• How Leap Years Work (and Why 1900 Wasn't One)

  The three Gregorian leap year rules explained simply, with examples, and why they matter when you count years or days back in time.

• How to Calculate Your Exact Age in Years, Months and Days

  A clear method for calculating exact age from a date of birth, including how to handle month ends and leap-day birthdays.

• How to Count the Days Between Two Dates

  How to count days between dates accurately, using day-of-year numbers, and how to convert the result to years, months and days.

• Why Months Are the Trickiest Unit in Date Math

  Months range from 28 to 31 days. Here is how calculators handle adding and subtracting months, and the end-of-month rule you should know.

• Decades and Centuries: Definitions and How to Count Them

  What counts as a decade or a century, why the 21st century started in 2001, and how to count decades and centuries back from today.

• How to Find the Day of the Week for Any Date

  Simple ways to find which weekday any date fell on, from anchor-day tricks to Zeller's congruence, plus a free day-of-the-week calculator.

• Inclusive vs Exclusive Day Counts: Which One Do You Need?

  Does a count include the start day, the end day, or both? Learn the difference between inclusive and exclusive day counting with examples.

• How Time Zones Affect Date Calculations

  Why the same moment can fall on different dates around the world, and how to avoid off-by-one errors when you count hours and days.

• How Many Days Are in a Year? 365, 366 and 365.2425 Explained

  A calendar year has 365 or 366 days, but the average is 365.2425. Here's why and when to use each number in calculations.

• What Date Will It Be 35 Years From Now?

  Find the exact date 35 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 34 Years From Now?

  Find the exact date 34 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 33 Years From Now?

  Find the exact date 33 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 32 Years From Now?

  Find the exact date 32 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 31 Years From Now?

  Find the exact date 31 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 30 Years From Now?

  Find the exact date 30 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 29 Years From Now?

  Find the exact date 29 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 28 Years From Now?

  Find the exact date 28 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 27 Years From Now?

  Find the exact date 27 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.

• What Date Will It Be 26 Years From Now?

  Find the exact date 26 years from now from today, updated daily. Includes the calculation method, worked examples and a table of nearby years.