Free Online Date Calculator
Runs 100% in your browser — your dates never leave your device.
Days between two dates
Add or subtract time from a date
Popular date answers
These are answered live from your current date every time you open the page:
About this date calculator
Date arithmetic is full of traps: February has 28 or 29 days, months end on the 30th or 31st, and adding "one month" to January 31 has no obvious answer. This calculator uses calendar-date math throughout (never timestamps), so daylight-saving changes can never shift a result by a day, and it handles leap years automatically.
The two modes cover the common cases: measuring a span ("how many days between these dates?") and projecting a date ("what date is 90 days from now?" — a question asked hundreds of thousands of times a month, usually for deadlines, notice periods and due dates).
Worked examples
Days between dates. From 1 January 2026 to 31 December 2026 is 364 days. From Christmas Day 2026 (25 December) to New Year's Day 2027 (1 January) is 7 days — the count is exclusive of the start date, so Monday to the following Monday is always 7. A span that crosses a leap day is one longer: 1 January 2024 to 1 January 2025 is 366 days because 2024 has a 29 February.
Projecting a date. 1 January 2026 plus 90 days is 1 April 2026, a Wednesday — the result also names the weekday, handy for spotting that a deadline lands on a weekend. When you add months, short months clamp: 31 January 2026 plus one month is 28 February 2026, but 31 January 2028 plus one month is 29 February 2028, because 2028 is a leap year. The same clamping applies to years: 29 February 2028 plus one year becomes 28 February 2029, since 2029 has no 29 February.
Who uses a date calculator
HR teams and employees check notice periods — "three months from 15 March" is 15 June, but "90 days from 15 March" is a different date, and confusing the two can cost a week's pay. Project managers turn "six weeks" into a calendar date before committing to a client. Freelancers convert payment terms (net 30, net 60) into exact due dates for invoices. Travellers count visa-free stay limits, and expecting parents count weeks to a due date. Landlords and tenants measure tenancy lengths and notice windows. Anyone can use it for the everyday questions too: how many days until a holiday, a birthday, or a product launch.
How to use
- To count a span: enter both dates and press Count days. Same date twice gives 0.
- To project: pick a start date (defaults to today), choose add or subtract, enter the amounts, and press Calculate date.
- At least one of days/weeks/months/years must be non-zero.
Limitations
- Days are calendar days — weekends and holidays are included, not excluded.
- Adding months clamps to the end of shorter months (Jan 31 + 1 month = Feb 28/29).
- Dates before year 1 or far-future dates may hit browser date limits; the tool validates input.
- The 5/7 business-day estimate ignores public holidays — it is a rough guide, not a payroll figure.
- When you subtract months or years, the same end-of-month clamping applies (e.g. 31 March minus one month is 29 February in a leap year, 28 February otherwise).
Frequently asked questions
How many days are between two dates?
Enter both dates and the calculator counts the calendar days from the first date to the second, exclusive of the start date. So from Monday to the following Monday is 7 days.
What date is N days from today?
Use the add/subtract box above with today's date pre-filled. Popular answers have their own pages: 90 days from today, 45 days from today and 30 days from today.
How do month additions handle month ends?
Adding months preserves the day of month where possible; when the target month is shorter, the date is clamped to the last day of that month.
Are weekends counted or only business days?
This calculator counts calendar days, including weekends and holidays. For a rough business-day estimate, multiply calendar days by 5/7.
Is my data uploaded anywhere?
No. The calculator runs 100% in your browser with JavaScript. Your dates never leave your device, are never stored, and never sent to any server.
How many days are in a year — 365 or 366?
It depends on whether the span includes a 29 February. From 1 January 2026 to 1 January 2027 is 365 days, but from 1 January 2024 to 1 January 2025 is 366 days because 2024 is a leap year. The calculator handles this automatically — you never need to check the calendar yourself.
What happens when I add one month to 31 January?
The date is clamped to the end of the shorter month: 31 January 2026 plus one month becomes 28 February 2026. In a leap year it becomes 29 February — 31 January 2028 plus one month is 29 February 2028. Years clamp the same way: 29 February 2028 plus one year is 28 February 2029.
Does daylight saving time affect the results?
No. All maths is done on calendar dates, never on timestamps, so a daylight-saving change can never shift a result by a day. Adding 90 days always means 90 calendar days, wherever you are.
Can I find a date in the past?
Yes. In the add/subtract box, switch the direction to Subtract (past) and enter the amounts. For example, 90 days before 1 January 2026 is 3 October 2025. The weekday is shown too, so you can see at a glance what day it fell on.