Date Calculator

How to use

Days between dates: pick any two dates and you get the difference in days, the same span expressed in years, months, and days, and an inclusive count that includes both endpoints. The order doesn't matter: swap the dates and the result is the same. Countdown to a date: pick one target date and you'll see how many days are left (or how many days ago it was) measured from today. Add days to a date: pick a start date, type how many days to add, or tap a preset to jump straight to 30, 45, 60, or 90 days from today. Negative numbers go backward, so -14 gives you the date two weeks before. Deadlines, probation periods, visa windows, medication refills, return policies: anything phrased as "n days from" is what this mode is for. Julian date: pick a date (today is filled in) to get its day of the year and the YYDDD code used on lot numbers, military documents, and logs, or type a code to turn it back into a date.

The rules behind the numbers

• Difference = second date − first date, in calendar days at midnight. Every day counts, weekends and holidays included.
• Inclusive count = difference + 1. Use it when both the first and last day count, like a 3-day rental that starts Friday and ends Sunday.
• Countdown: the target day itself shows as "today"; one day out is "1 day left"; one day past is "1 day ago".
• Day of the year counts January 1 as day 1, so December 31 is day 365, or 366 in a leap year. YYDDD puts the last two digits of the year in front of the three-digit day: 26276. YDDD keeps one year digit, so it repeats every ten years. That is why the reverse lookup asks for a year.
• ISO week number: weeks run Monday to Sunday, and week 1 is the week with the year's first Thursday (ISO 8601). A year has 52 weeks, or 53 when it starts on a Thursday (or a Wednesday in a leap year). Some US calendars start weeks on Sunday and call the week of January 1 week 1, so their numbers can differ by one.
• Astronomical Julian Day follows the U.S. Naval Observatory definition: days since noon Universal Time on January 1, 4713 BC, so a date at 00:00 UTC ends in .5. It is a different number from the YYDDD code, and neither one is a date in the old Julian calendar.
• Today means your device's date. Near midnight it can differ from a system that runs on UTC by one day.
• Years, months, days: calendar-based, the same way ages are computed: whole years first, then whole months, then leftover days. Because months have 28 to 31 days, a months-based figure can shift by a day depending on the anchor; this calculator anchors on the start date.

Examples

From July 22, 2026, adding 90 days lands on Tuesday, October 20, 2026. That's what "90 days from today" means on that day: 9 remaining days of July, then 31 in August, 30 in September, and 20 days into October. Between January 1 and April 10 of a common year there are 99 days, or 100 with the inclusive count (one more in a leap year). And if today is July 22, 2026 and your deadline is November 19, 2026, the countdown shows 120 days left.

Week numbers 2027

ISO 8601 weeks for 2027, Monday to Sunday.

Julian date calendar 2026

Day of the year for every date in 2026. Find the month column and the day row; the YYDDD code is the year's last two digits followed by this number.

Julian date calendar 2027

The same chart for 2027. In a leap year every date from March 1 on is one higher.

Frequently asked questions

What is 90 days from today?

Ninety calendar days from today, weekends and holidays included. Tap the +90 days preset above and the calculator fills in today's date and shows the answer with its weekday. Ninety days is close to three months but not the same thing: from March 1, 2026 it lands on May 30, 2026, while three months later is June 1, 2026. Contract, return-policy, and visa windows written as 90 days almost always mean this straight calendar count.

What is 60 days from today?

Sixty calendar days from today. The +60 days preset fills it in. This is the usual window for net-60 payment terms and rebate deadlines. It isn't quite two months either: 60 days after January 1, 2026 is March 2, 2026, because February has 28 days that year, while the same count from January 1, 2024 lands on March 1.

What is 45 days from today?

Forty-five calendar days from today. The +45 days preset fills it in. It is a length that shows up in escrow timelines and some tax deadlines. Starting from the 1st of a 31-day month, 45 days lands on the 15th of the following month: January 1, 2026 to February 15, 2026, for example.

What is 30 days from today?

Thirty calendar days from today. The +30 days preset fills it in. Note that 30 days and one month are not always the same thing: adding one month to January 31 gives February 28, or February 29 in a leap year, but adding 30 days gives March 2, or March 1 in a leap year. When a rule says days, count days.

How do I count the days between two dates?

Pick both dates in the Days between dates mode. The difference is the later date minus the earlier one in calendar days: January 1 to January 31, for example, is 30 days apart. The order you enter them in doesn't matter; the calculator sorts the two dates itself.

Does the count include both the start and end dates?

The main difference result counts the gap only: January 1 to January 2 is 1 day apart. When both endpoints matter (rentals, prescriptions, attendance streaks), use the inclusive count, which is always the difference plus 1. Same two dates, two honest answers to two different questions.

Do weekends and holidays count?

Yes. Everything on this page counts calendar days, so weekends and holidays are included. Business-day counting, which skips them, is a different calculation, but most rules phrased as n days in everyday life mean calendar days unless they explicitly say business days.

What is today's Julian date?

In everyday use a Julian date is the year plus the day of the year: YYDDD, like 26276 for October 3, 2026 (the 276th day of 2026). The Julian date section above shows today's code as soon as the page opens, using your device's date. Shorter forms drop digits: 276 is the day alone, and 6276 keeps only the last digit of the year.

How do I convert a Julian date back to a calendar date?

Type the code into Julian code to date. Five digits are read as YYDDD in the 2000s, so 27032 is February 1, 2027. Four digits (YDDD) are read as the latest year ending in that digit up to the year you enter, and three digits are a day of the year you enter. Day 366 exists only in leap years: 28366 is December 31, 2028, but 26366 is not a date.

Is a Julian date the same as the Julian calendar?

No. A Julian date in the YYDDD sense is just a day count within our ordinary Gregorian year. The astronomical Julian Day is another count: days since noon UT on January 1, 4713 BC, so midnight UTC on October 3, 2026 is JD 2461316.5. The Julian calendar is the older calendar, now 13 days behind; this page does not convert to it.

What week number is it today?

The page shows today's ISO 8601 week number at the top, from your device's date. ISO weeks start on Monday, and week 1 is the week that contains the year's first Thursday, so January 1 can belong to the last week of the previous year. January 1, 2027 is a Friday and falls in week 53 of 2026; week 1 of 2027 starts on Monday, January 4.

Why do some years have 53 weeks?

An ISO year has 53 weeks when it starts on a Thursday, or on a Wednesday in a leap year (every five or six years). 2026 starts on a Thursday, so it has 53 weeks, ending on Sunday, January 3, 2027. Calendars that start weeks on Sunday and count the week of January 1 as week 1 can show a different number.

Is anything I type sent to a server?

No. Every calculation runs in your browser, and the dates you enter are never sent to or stored on a server. One thing to know: the Copy result link button puts those values into the link address itself, so anyone you send the link to can see the same dates.