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CALCULATOR EXPERT
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Find the number of days between two dates, or add/subtract days, weeks, months, and years from a date.
The "Days Between Dates" tab calculates the exact span between two calendar dates, breaking it down into years, months, and days, along with total days, weeks, weekdays, and weekend days. The "Add / Subtract Days" tab takes a starting date and shifts it forward or backward by a chosen number of days, weeks, months, or years, following the standard Gregorian calendar rules — including leap years and varying month lengths.
From January 1, 2026 to August 16, 2026, the difference is 7 months, 15 days (227 total days). Adding 90 days to August 16, 2026 lands on November 14, 2026.
A date calculator answers one of two everyday questions: "How much time is between these two dates?" or "What date will it be after adding or subtracting a certain amount of time?" While these calculations sound simple, doing them by hand quickly becomes error-prone once you account for varying month lengths, leap years, and the fact that months and years don't divide evenly into days. This tool automates that math instantly and accurately, following the same Gregorian calendar rules used almost everywhere in the world.
When finding the difference between two dates, the calculator first works out the gap in whole years, months, and days — similar to how you'd count on a calendar by hand, moving month by month and adjusting for how many days each month actually has. It then separately calculates the total number of days between the two dates as a single number, which is useful for things like contract durations, project timelines, or figuring out how many days remain until a deadline. It also breaks that total down into weekdays and weekend days, which is helpful for business day calculations such as estimating delivery times or working days remaining in a project.
The second mode works in reverse — instead of comparing two known dates, you start from one date and shift it by a chosen amount of time. This is useful for figuring out things like a due date 30 days from an invoice, a return deadline 90 days after a purchase, or an anniversary a certain number of years in the future. When adding or subtracting months or years, the calculator adjusts intelligently for month-end edge cases — for example, adding one month to January 31 lands on the last valid day of February rather than an invalid date like "February 31."
Nearly every country in the world uses the Gregorian calendar for civil and business purposes, even in places where a different calendar (such as the Islamic, Hebrew, or Hindu calendar) is also used for religious or cultural events. The Gregorian calendar has 12 months of varying length (28 to 31 days) and adds a leap day every four years (with some century-based exceptions) to keep the calendar aligned with Earth's orbit around the sun. Because this calculator follows Gregorian rules precisely, its results are accurate for legal, financial, and administrative purposes anywhere in the world.
Many business and legal calculations depend specifically on "business days" rather than calendar days — for example, a delivery window quoted in business days excludes Saturdays and Sundays. This calculator separates the total day count into weekdays (Monday through Friday) and weekend days (Saturday and Sunday), which gives a more accurate picture for scheduling purposes. Note that this calculation does not account for public holidays, which vary by country and region, so for holiday-sensitive calculations you may need to adjust the result manually.