Age & Date Calculators
Two precise calculators for everyday questions about time: how old someone is to the day, and how many days separate any two dates.
Knowing an exact age in years, months, and days is more useful than it sounds. Schools sort children by age cutoff. Pension and retirement schemes pay based on exact years served. Visa categories switch at exact birthday boundaries. Health screening schedules are tied to age in months for infants and decades for adults. The Age Calculator on this page returns a precise breakdown using the same calendar-aware algorithm that scientific computing libraries use, so January 31 plus one month is February 28 in a non-leap year and February 29 in a leap year, and a person born on February 29 turns one year older on March 1 in non-leap years. The Days Between Dates calculator answers a different question: how many whole days separate two specific dates? That is the number reservation systems, project schedulers, and shipment trackers care about. It is order-independent, so swapping the dates returns the same count, and it correctly accounts for leap years across century boundaries. Both calculators run entirely in your browser. Nothing about your dates leaves your device, no data is logged, and no account is required. Bookmark a calculation and the URL preserves your inputs so you can share or revisit it later.
Choose a calculator
More date-math tools coming soon — birth-date age and exact day spans for now.
Age Calculator
Years, months, days, weeks, and total days lived from a date of birth.
Days Between Dates Calculator
Absolute number of days between any two calendar dates.
Days From Today
Find the calendar date N days from today (negative N = N days ago).
Age on Date
Exact age in years, months and days a person has on a specific target date.
Business Days Between
Count Monday-through-Friday days between two dates (inclusive of both endpoints when they are weekdays).
Calculator comparison
| Tool | Inputs | Outputs | Best used for |
|---|---|---|---|
| Age Calculator | Date of birth | Years, months, days, weeks, and total days lived from a date of birth. | Knowing how old you or someone else is to the day, including months and weeks lived. |
| Days Between Dates Calculator | First date + Second date | Absolute number of days between any two calendar dates. | Counting days between two specific dates for scheduling, contracts, or trip planning. |
FAQ
What is the difference between the two calculators?
The Age Calculator takes one date (a birthday) and computes how much time has passed from that date to today, broken into years, months, days, weeks lived, and total days lived. The Days Between Dates calculator takes two arbitrary dates and returns the absolute number of days between them — useful when neither date is today.
Do these calculators use my time zone?
Both calculators normalize all dates to UTC and ignore the time-of-day component. This means results are deterministic regardless of where in the world you load the page. The trade-off is that on the day of a birthday, results may show a one-day difference from a clock-based calculation done in your local time zone.
Are leap years handled correctly?
Yes. Both calculators use the proleptic Gregorian calendar, which includes leap years every four years except for years divisible by 100 but not by 400 (so 1900 was not a leap year and 2000 was). Spans that cross February 29 are counted accurately to the day.
Can I use the calculators for historical dates?
Yes — any date supported by your browser is valid input, including dates from past centuries. Note that very old dates predate the Gregorian calendar's introduction in 1582, so the result is the proleptic Gregorian count, not the count from the Julian calendar in use at the time.
Does the page send my dates to a server?
No. The math runs entirely in your browser. The dates appear in the URL only because we encode them there so you can bookmark or share a calculation, and the URL never leaves your browser unless you choose to share it.