Time and Date Calculators: Every Tool for Counting Days, Weeks, and Years
Date math is fiddly by hand. Months are different lengths, leap years shift everything by a day, and "how many working days is that?" turns a simple subtraction into a chore. Whatever you're trying to count — the weeks left in the year, your exact age, the hours on a timesheet, the gap between two dates — there's a free tool that does it in your browser. Here's the map, grouped by what you're actually trying to find out.
Counting down: weeks and days left
The most-asked date question of all is "how much of the year is left?" A year is 52.14 weeks, so the answer changes daily. The weeks left in the year calculator shows the live figure, and our full walkthrough covers how many weeks are left in the year and how to count them by hand. Counting down to one specific day instead — a launch, a birthday, a holiday? The days until calculator targets any date you pick.
Your age, down to the day
"How old am I exactly?" is harder than it sounds once you account for leap years. The age calculator gives your age in years, months, and days from your birth date, and the age in days calculator converts your whole life into a single day count — a surprisingly motivating number. Our full walkthrough covers how to calculate your exact age, leap years and all.
The gap between two people or two dates
Comparing two dates is its own kind of math. The age difference calculator tells you the exact gap between two birth dates, and the days between dates calculator counts the days from one date to another — useful for deadlines, anniversaries, or how long ago something happened. Here's the full guide to how to calculate the age difference between two people.
Hours, shifts, and time math
Time math trips people up because it's base-60, not base-10. The hours calculator works out the hours and minutes between two clock times — handy for shifts, timesheets, and "wait, how long was that meeting?" without converting everything to decimals in your head. The full guide covers how to calculate hours between two times, including overnight shifts and decimal hours for payroll.
| If you want to… | Use | Full guide |
|---|---|---|
| See how much of the year is left | Weeks left in the year | Weeks left in the year |
| Count down to a specific date | Days until calculator | — |
| Find your exact age | Age calculator | Calculate your exact age |
| Compare two birth dates | Age difference calculator | Age difference between two people |
| Count the days between two dates | Days between dates | — |
| Work out hours between two times | Hours calculator | Hours between two times |
Why date math is trickier than it looks
Dates break every rule your mental arithmetic relies on. Months run 28 to 31 days, so "three months from now" isn't a fixed number of days. Leap years slip an extra day into February every four years (but not every century, unless it divides by 400 — the reason 2000 was a leap year and 1900 wasn't). And time itself is base-60, so adding 45 minutes to 4:30 isn't 4:75 — it's 5:15. Each of these is a small trap, and stacking two or three of them is how you end up a day off on a deadline. That's the whole reason these tools exist: they hold the edge cases so you don't have to.
How to pick the right one
Start from the shape of your question. If it ends in a countdown ("how long until…", "how much is left"), you want the weeks-left or days-until tools. If it's about a person ("how old…", "how far apart in age…"), reach for the age tools. If it's two fixed dates or two clock times, use the days-between or hours tools. Every one of them is free, needs no signup, and runs entirely in your browser — nothing is uploaded.
Start with the year
If you're not sure where to begin, begin with the calendar's own countdown: how many weeks are left in the year. It's the question most people are really asking, and it's the fastest way to turn "the year's almost gone" into a number you can plan around.
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