Days Calculator: Count Days Between Dates & Add Days

Count days between dates, add days to find deadlines, or calculate date differences. Free, instant, handles leap years.

Count days between two dates, add days to find a future date, or calculate deadlines instantly.

Free days calculator — count days between two dates, add or subtract days, weeks, or months, and calculate deadlines instantly. Handles leap years and varying month lengths. Useful for planning, billing cycles, contracts, and everyday calendar math.

How this page is maintained

  • Steps and copy are checked against the current tool behavior.
  • Browser limits, file-size constraints, or compatibility gaps are documented when relevant.
  • Unless a page explicitly says otherwise, files and text stay in the browser during processing.

Your Free Days Calculator & Date Counter

Need to count days between two dates, figure out what date is 90 days from now, or calculate a deadline? This date calculator handles all common calendar math instantly. Enter your dates, get your answer—no sign-up, no server processing.

Eliminating Mental Calendar Math

Manually calculating the exact number of days between February 14th and October 31st across different years is highly prone to human error, especially when factoring in leap years or irregular month lengths. Our Date Calculator offloads this arithmetic to a mathematically flawless browser engine.

Two Modes: Days Between & Add Days

This tool is built for two distinct workflows:

  1. Date Counter (Days Between): Input a start and end date to instantly see the total days, weeks breakdown, and full year/month/day decomposition between them. Perfect for project timelines, contract durations, event countdowns, or answering "how many days until..." questions.
  2. Day Calculator (Add/Subtract): Enter a start date and a number of days, weeks, or months to project forward or backward. Ideal for deadline planning ("What date is 60 days from today?"), billing cycles, due dates, and notice periods.

Common Questions This Calculator Answers

  • How many days between two dates?
  • What date is 30 / 60 / 90 days from today?
  • How many days until Christmas, a wedding, or a deadline?
  • When does a 14-day return window or 60-day notice period end?
  • How many days have I been alive?

The Leap Year Guarantee

Because this tool natively leverages your browser's underlying Date object API rather than a hacky server-side script, it inherently understands the complete Gregorian calendar. It flawlessly accounts for February 29th leap years, 30-day months, and varying month lengths without error.

How to Count the Days Between Two Dates and Add Days to a Date

The page has two modes and they answer different questions. Days between takes a start date and an end date and reports the total number of days along with a years, months and days breakdown. Add or subtract takes one date plus an amount and a unit, where the units are days, weeks, months, years, or years with a spare count of days.

The counting rule is the part people get wrong. The end date is not counted, so the number shown is the distance from the start date to the end date, not the number of dates inside the range. The tool also sorts the two dates before subtracting, so entering the later date first still returns a positive number rather than a negative one.

Worked example. Compare 1 January 2026 with 31 December 2026. The total is 364 days, with a breakdown of 11 months and 30 days, because the range stops one day short of the final date. Add one for an inclusive count of 365, which matches the length of 2026 as a non-leap year. Compare 1 January 2024 with 1 January 2025 instead and the same calculation gives 366 days, since 2024 is a leap year. In add mode, take 31 January 2026 and add 1 month: the result is 28 February 2026, because a month step clamps to the last day of the shorter month instead of spilling into March. Add 1 year to 29 February 2024 and the result is 28 February 2025 for the same reason.

A few limits are worth noting. Dates must be entered in the year-month-day form with a four digit year, and results outside the years 100 to 9999 are rejected rather than shown as a broken value. Amounts must be whole numbers and cannot be negative, and the years plus days unit exists for cases such as one year and 90 days, which is a real contract term rather than a rounding exercise.

If you need the count that includes the end date, add one yourself, or work through the days between dates walkthrough for more examples. The age calculator answers the birthday version of the same question, and the roundup of what date is 90 days from today covers the arithmetic from the other direction.

Key features

  • Date Difference: Calculate the exact number of days, or a breakdown of years, months, and days between two dates.
  • Add or Subtract Time: Find out what date it will be in 30 days, or what date it was 5 weeks ago.

Frequently asked questions

Does this include the end date in the count?

The "days between" calculation typically counts the duration, so it is effectively exclusive of the start date and inclusive of the end date (or vice versa). It measures the time span.

Does it handle leap years?

Yes. Calendar-day calculations handle leap years and daylight saving changes. Adding a year to February 29 uses February 28 when the destination year is not a leap year. Adding months uses the last valid day when needed.

Can I calculate business days only?

This tool counts calendar days, including weekends and public holidays. It does not calculate business days.

How far back can I calculate?

You can calculate dates from year 100 AD up to year 9999. It is perfect for historical research or long-term planning.

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