Pick a mode: count the days between two dates (with weeks, months, and weekday/weekend breakdowns), or add or subtract a number of days from a start date to find the resulting date.
How the date calculator works
It has two modes. Days between two dates counts the exact number of days from one date to another — leap years and month lengths handled — and breaks the answer down into weeks, approximate months, and weekdays versus weekend days. Add or subtract days starts from a date, moves forward or backward a given number of days, and tells you exactly which calendar date (and weekday) you land on.
The counting convention
days between = end date − start date (exclusive — counts the nights, not both endpoints)
June 1 to June 8 is 7 days by this convention — think of a hotel stay: 7 nights, even though you're present on 8 calendar dates. This exclusive count is the standard for durations, deadlines, and date arithmetic. If your rule requires counting both endpoints (some legal deadlines do), add 1.
Worked example
June 1, 2026 → July 14, 2026: the remaining 29 days of June plus 14 days of July = 43 days. That's 6 weeks and 1 day, or about 1 month and 13 days — made up of 31 weekdays and 12 weekend days.
June 1, 2026 + 90 days: 29 days finish June (June 30), 31 more finish July (day 60), and 30 more land on Sunday, August 30, 2026.
The business-days caveat
The weekday count here excludes Saturdays and Sundays — but "business days" in the wild also exclude public holidays, and those depend on where you are and who's counting. A 10-business-day window spanning Thanksgiving week is longer in the US than the raw weekday math suggests; the same window in the UK isn't. Courts, banks, and shipping carriers each keep their own holiday calendars, so when a deadline really matters, use this calculator for the weekday arithmetic and then check the relevant holiday list yourself. No generic calculator knows that your county courthouse closes for a local founders' day.
Frequently asked questions
Does the day count include both the start and end dates?
This calculator counts the span between the dates — the nights, if you think of it as a hotel stay. June 1 to June 8 is 7 days. If your situation needs both endpoints counted (some deadline rules work that way), add 1 to the result.
How do I count only business days between two dates?
The weekdays row in the results excludes Saturdays and Sundays, which gets you most of the way there. True business-day counts also skip public holidays, which vary by country, state, and even industry — so for legal or payroll deadlines, check the specific holiday calendar that applies to you.
How do I calculate a date 90 days from today?
Switch to "add or subtract days" mode, enter today's date and 90, and you'll get the exact calendar date and weekday. The calculator handles month lengths and leap years automatically — no counting on your fingers across three different month lengths.
Can I subtract days from a date?
Yes — enter a negative number in add/subtract mode. For example, −45 days from a due date tells you when a 45-day notice period must begin. The calculator counts backward through months and leap years correctly.
Why is the months-and-days result labeled approximate?
Because months aren't a fixed unit — they run 28 to 31 days. "1 month and 13 days" from June 1 means something slightly different than from February 1. The day count is exact; the month breakdown follows standard calendar convention (whole months first, then leftover days) but can't be more precise than months themselves are.