Days Between Dates
Calculate the number of days between two dates
How to use Days Between Dates
Calculate the exact number of days, weeks and months between two dates. Business days option. Free online date calculator.
When do you need to count days between dates?
Calculating exact date differences is surprisingly error-prone mentally — months have different lengths, leap years add a day, and timezone changes can shift boundaries. A date calculator gives the precise answer instantly.
- Project deadlines: How many working days remain until a deadline? Calculate the total days and mentally subtract weekends, or use a business day calculator.
- Legal and contractual deadlines: Contracts specify timelines in days — a 30-day notice period, a 14-day cooling-off period, or a 90-day payment term all require precise date arithmetic.
- Age and anniversary tracking: How many days until a milestone birthday? How many days have you been married, or running your business?
- Pregnancy and medical timelines: Pregnancy is counted in weeks from the last menstrual period — exactly 280 days or 40 weeks. Medical treatment intervals also require precise date calculation.
- Financial calculations: Bonds, loans, and leases calculate interest on an exact number of days. Day-count conventions (ACT/365, ACT/360) matter in fixed income finance.
Leap years: A leap year occurs every 4 years (divisible by 4), except for century years not divisible by 400. 2000 was a leap year; 1900 was not. This tool accounts for all leap year rules automatically.
Frequently Asked Questions
How are business days different from calendar days?
Calendar days count every day including weekends and public holidays. Business days (working days) exclude Saturdays, Sundays, and public holidays. A 5 calendar-day week typically contains 5 business days, but a week spanning a public holiday contains 4. This tool counts calendar days — for business days, also account for holidays manually.
What is the difference between 'days between' and 'days until'?
Both calculate a date difference. 'Days between' counts the interval between two past or future dates. 'Days until' is specifically from today to a future date. This calculator handles both — just set one date to today's date for 'days until' calculations.
Does the calculator account for leap years?
Yes. The calculation uses the actual calendar, including all leap years in the range. A span from January 1, 2023 to January 1, 2025 correctly counts as 730 days (2024 is a leap year), not 729.
What is a Unix timestamp and how does it relate to dates?
A Unix timestamp counts seconds since January 1, 1970 (the Unix epoch). Subtract two timestamps and divide by 86,400 (seconds per day) to get the number of days between them. Developers use this for date arithmetic in code because it avoids timezone and calendar complexity.
Why do different countries count deadlines differently?
Some legal systems use 'calendar days' (all days), others use 'business days', and some exclude the start date or include the end date. Always confirm the counting convention for legal deadlines — 'within 30 days' may mean 30 calendar days from tomorrow in one jurisdiction and 30 business days from today in another.
Date calculator vs spreadsheet vs programming
A spreadsheet (Excel DATEDIF, Google Sheets DAYS) handles date arithmetic in formulas — useful when part of a larger calculation. In Python, (date2-date1).days gives the difference in one line. In JavaScript, subtract two Date objects and divide by milliseconds per day. A browser-based calculator is fastest for ad-hoc calculations without opening a spreadsheet or writing code.