What is date difference calculator?
A date difference calculator measures the gap between two calendar dates. It is useful for project plans, contract terms, pregnancy and travel countdowns, notice periods, warranties and billing cycles.
The result is shown in several ways at once. You get years, months and days for easy reading, the total number of days for formulas, and a count of weekdays so you can plan work time.
How to use the date difference calculator
- Enter a start date and an end date. The order does not matter.
- Press Calculate.
- Read the full difference, then check the weekday count if you need working days.
How the date difference calculator works
Total days are found by converting both dates to a day number and subtracting. Years, months and days are found by borrowing, just like manual subtraction. Weekdays are counted by stepping through each date from the start and skipping Saturdays and Sundays. Public holidays are not removed.
Worked example
Common uses of the date difference calculator
- Counting the length of a project, trip or lease.
- Finding how many working days remain before a deadline.
- Checking the days between an invoice date and a payment date.
- Measuring the gap between two life events, such as a wedding and a first child.
- Finding the length of a notice period or a warranty.
Tips and common mistakes
For a business deadline, take the weekday count and subtract any public holidays in your country.
Whether the end date is included is a common source of confusion. This tool counts the number of nights between the dates, so add one day if you want to count both the first and last day.
Background: what to know before you rely on it
Calendar arithmetic is full of small traps. A month can be 28, 29, 30 or 31 days, so two months after 31 January is not a fixed number of days. Counting inclusive or exclusive of the end date also changes the answer by one. Businesses often count weekdays only, while courts and contracts may count every calendar day. The safest habit is to write the rule you use next to the number, for example 59 days, end date not counted. This calculator shows years, months and days as well as totals, so you can pick the form that matches your document.
Private, free and fast
This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all date and time tools, or browse the full list of tools.
Frequently asked questions
How many days are between two dates?
Subtract the earlier date from the later one. This tool does it for you and also shows weeks, months, years and weekdays.
Does it count the end date?
No. It counts the gap between the dates. Add one day if you want both ends included.
Does it skip public holidays?
No. It skips Saturdays and Sundays only.
Can the end date be earlier than the start date?
Yes. The tool swaps them automatically.
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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. For legal deadlines, confirm how your contract or court counts days.