Date calculator
Days between dates, business days, and what the date will be in 90 days.
How it works
- 01Choose whether to count the days between two dates, or add or subtract time from a date.
- 02Pick your dates and amounts, and decide whether the end date counts.
- 03Open "Weekends & holidays" to change days off or paste a list of holidays to skip.
Questions
›Does it count the start and end dates?
By default the start date counts and the end date doesn't, so Monday to Tuesday is 1 day. Tick "include the end date" to count both, which adds one day and is what you want for things like how many days a trip or a booking lasts.
›How are business days counted?
Business days are every day except your days off (Saturday and Sunday unless you change them) and any holidays you list. Holidays that fall on a day off are only skipped once. Adding 1 business day to a Friday gives the next Monday.
›What happens when I add a month to January 31?
February has no 31st, so the result is the last day of February. That's the usual rule for adding months, and the calculator tells you when it has applied it.
›Do time zones or daylight saving affect the result?
No. Dates are counted as calendar days, never as hours, so the day the clocks change still counts as exactly one day.
›Is my data uploaded anywhere?
No. This tool runs entirely in your browser, and Rounder never sends what you type or drop in to a server, ours or anyone else's. Once the page has loaded, along with any AI model the tool uses, it even works offline.