Quick Answer: How to Calculate Days Between Two Dates
To calculate the days between two dates: subtract the earlier date from the later date. Each day equals 86,400 seconds. For example, from 1 January 2026 to 30 June 2026 = 180 days. Our calculator handles leap years (2024 = 366 days) and varying month lengths (28–31 days) automatically. Use the calculator below for an instant result.
Calculate Days Between Dates Instantly
Finding the number of days between two dates is simple: enter your start date and end date below, and our calculator will instantly show you the exact number of days, weeks, and months between them. This tool accounts for varying month lengths (28-31 days) and leap years, ensuring accurate results every time.
Whether you're calculating how many days until a visa expires, tracking payment terms like Net 30 or Net 60, planning a pregnancy timeline, or simply curious about the time between two events, this guide and calculator have you covered.
How to Calculate Days Between Two Dates
Calculating the days between two dates manually can be tricky due to varying month lengths and leap years. Here's how it works:
The Simple Formula
Days Between = End Date − Start Date
While the concept is simple, the calculation must account for:
- Months with different lengths: January has 31 days, February has 28 (or 29), April has 30, etc.
- Leap years: Every 4 years, February has 29 days (with exceptions for century years not divisible by 400)
- Year boundaries: Calculations spanning multiple years need to account for all intervening days
Step-by-Step Manual Calculation
- Count remaining days in the start month: From the start date to the end of that month
- Add days for complete months: Sum the days in each full month between start and end
- Add days in the final month: From the 1st to the end date
- Verify leap years: If spanning February, check if it's a leap year
Or simply use our free date calculator and let us handle the maths!
Common Date Calculation Examples
Here are some frequently calculated date durations and their typical uses:
| Duration |
Days |
Common Use |
| 1 Week |
7 days |
Short-term deadlines, delivery estimates |
| 2 Weeks |
14 days |
Notice periods, quarantine periods |
| 30 Days |
30 days |
Net 30 payment terms, trial periods |
| 60 Days |
60 days |
Net 60 payment terms, visa processing |
| 90 Days |
90 days |
Schengen visa limit, probation periods |
| 180 Days |
180 days |
Schengen 180-day rolling period, tax residency |
| 280 Days |
280 days |
Pregnancy due date (40 weeks from LMP) |
| 365 Days |
365 days |
1 year (non-leap), annual subscriptions |
| 366 Days |
366 days |
1 year (leap year) |
Understanding Inclusive vs Exclusive Counting
When calculating days between dates, it's important to understand what's being counted:
Exclusive Counting (Standard)
Most calculators, including ours, use exclusive counting—the number of days between two dates, not including both endpoints.
Example: From 1 January to 3 January = 2 days (the 2nd and 3rd, or just counting the gap)
Inclusive Counting
Some applications require inclusive counting—including both the start and end dates.
Example: From 1 January to 3 January = 3 days (1st, 2nd, and 3rd)
Which Should You Use?
- Visa calculations: Usually exclusive (days spent = arrival to departure)
- Payment terms: Usually exclusive (Net 30 = due 30 days after invoice date)
- Pregnancy: Inclusive (280 days from LMP includes the first day)
- Event countdowns: Usually exclusive (days until = not including today)
Tip: If you need inclusive counting, simply add 1 to the calculator result.
Leap Year Considerations
Leap years add an extra day (29 February) every four years, which affects date calculations spanning this period.
Leap Year Rules
- A year is a leap year if it's divisible by 4
- Exception: Century years (1900, 2000, 2100) must be divisible by 400
- 2024 and 2028 are leap years; 2025, 2026, 2027 are not
Recent and Upcoming Leap Years
| Year | Leap Year? | Days in February |
|---|
| 2024 | Yes | 29 |
| 2025 | No | 28 |
| 2026 | No | 28 |
| 2027 | No | 28 |
| 2028 | Yes | 29 |
Our calculator automatically handles leap years, so you don't need to worry about manual adjustments.
Frequently Asked Questions
How do I calculate the number of days between two dates?
The easiest way is to use our date calculator. Enter your start date and end date, and it instantly shows the number of days between them. For manual calculation, subtract the start date from the end date while accounting for varying month lengths and leap years.
Does the calculator include the start and end dates?
Our calculator uses exclusive counting—it shows the number of days between the two dates. If you need to include both dates in your count, add 1 to the result.
How do I calculate business days only?
Business days exclude weekends (Saturday and Sunday) and public holidays. To calculate business days, you'd need to subtract weekends and holidays from the total calendar days. Our main calculator shows calendar days; for business days, count the weeks (×5) and add any remaining weekdays.
What is 90 days from today?
Use our date calculator with today's date as the start, select "Add," and enter 90 days. This is commonly used for Schengen visa tracking and probation periods.
How do I calculate weeks and months between dates?
Once you have the number of days, divide by 7 for weeks or by 30.44 (average month length) for approximate months. Our calculator also provides these conversions automatically.
Why do different calculators give different results?
The difference usually comes down to inclusive vs exclusive counting. Some calculators include the start date, some include the end date, and some include both. Always check the calculator's methodology to ensure it matches your needs.
How accurate is this calculator?
Our calculator is 100% accurate for calendar days. It correctly handles varying month lengths (28-31 days), leap years, and calculations spanning multiple years. The calculations are performed using reliable date arithmetic.