Days Between Dates Calculator
Calculate the exact number of days between any two dates. Get results in total days, weeks and days, months and days, and years, months, and days — plus an optional business days mode that skips weekends and holidays. Free, private, and runs entirely in your browser.
What does this days between dates calculator do?
This tool calculates the exact number of days between any two calendar dates. Enter a start date and an end date, and it returns the difference in several formats: total days, weeks and days, months and days, and years, months, and days. It's the simplest way to answer the question "how long is it between these two dates?" without pulling out a calendar and counting by hand.
By default, the calculator uses the standard difference (end date minus start date), which is what most people mean when they ask how many days are between two dates. For example, from January 1 to January 5 is 4 days. If you need to include both endpoints — sometimes useful for project durations or inclusive date ranges — there's a toggle to count inclusively, which would give 5 days for that same example.
If you need to count only working days (the kind that actually matter for business deadlines, shipping estimates, or contract notice periods), switch to Business Days mode. That mode skips weekends and any custom holidays you paste in, giving you the exact number of working days between the two dates.
How to calculate days between two dates
- Choose your mode: Use All Days for the total calendar-day difference, or Business Days to skip weekends and holidays.
- Enter the start date: Pick the earlier date of the range. This is the beginning of the period you're measuring.
- Enter the end date: Pick the later date. The calculator will find the difference between the two.
- Adjust options if needed: In All Days mode, toggle inclusive counting if you want both endpoints counted. In Business Days mode, customize the weekend days and paste any holidays you want to exclude.
- Click Calculate Days: The total number of days appears immediately, along with weeks, months, and years equivalents in the format grid below.
Why use this calculator?
Multiple formats at once
Get the difference in days, weeks and days, months and days, and years, months, and days — all at the same time, no extra clicks.
Business days mode
Switch to working-days counting to skip weekends and custom holidays. Perfect for contract deadlines and shipping estimates.
Leap year handling
Correctly handles leap years, month lengths, and century rules, so the count is always accurate no matter how far apart the dates are.
Custom weekends
Not everyone works Monday to Friday. Click the day chips to define your own weekend — Friday–Saturday, Sunday only, or any combination.
100% private
Everything runs in your browser. No dates are sent to a server. Close the tab and the data is gone.
Works offline
Once the page loads, the calculator keeps working without an internet connection. Perfect for flights or remote areas.
Common use cases for days-between-dates
Personal planning
- Countdowns: Find out exactly how many days until a vacation, wedding, exam, or birthday.
- Milestone tracking: See how many days you've been at a habit, job, or relationship.
- Project timelines: Measure how long ago something happened, or how long until a deadline.
Business and finance
- Invoice aging: Find how many days an invoice is past due by comparing the due date with today.
- Interest accrual: Count the exact days between two dates for daily-interest calculations.
- Project durations: Measure the length of a phase in calendar days or business days.
Legal and contracts
- Notice periods: Verify how many days remain in a contractual notice window.
- Statute of limitations: Count the days elapsed since an event for filing deadlines.
- Contract terms: Confirm the exact duration of a fixed-term agreement.
Travel and logistics
- Trip length: Count the days of a vacation or business trip.
- Visa stays: Verify how many days you've spent in a country to stay within visa limits.
- Shipping windows: Work out the business days between dispatch and expected delivery.
Health and fitness
- Pregnancy tracking: Count days since conception or last menstrual period.
- Medication cycles: Track the days between doses or treatment cycles.
- Habit streaks: Count consecutive days between two milestones.
How the days-between-dates calculation works
At its simplest, the calculation is a subtraction: end date − start date = number of days. But calendars are messier than that, because months have different lengths and leap years add an extra day in February. Here's how each of the formats is derived:
| Format | How it's calculated | Example (Jan 1 → Mar 15) |
|---|---|---|
| Total days | Direct difference in calendar days between the two dates. | 73 days |
| Weeks & days | Total days ÷ 7 gives whole weeks; the remainder is leftover days. | 10 weeks, 3 days |
| Months & days | Count whole months between the dates, then count remaining days. | 2 months, 14 days |
| Years, months & days | Count whole years, then remaining whole months, then remaining days. | 0 years, 2 months, 14 days |
Because months vary in length, the "months and days" result can look different depending on where the two dates fall. That's why providing the total-days figure alongside it is important — it's the unambiguous answer, and the other formats are just convenient ways of expressing the same span.
Inclusive vs exclusive counting: which is right?
The difference between inclusive and exclusive counting is whether the first and last day of the range are counted as part of the span.
- Exclusive counting (the default) counts the gap between the two dates: from January 1 to January 5 is 4 days. This is the standard convention and matches how most people think about "days between".
- Inclusive counting counts both endpoints: from January 1 to January 5 is 5 days. This is often used for project durations, event lengths, or date ranges that include both the start and end days.
If you're measuring how much time passed between two events, exclusive is usually correct. If you're counting how many days a project takes when the first and last day both count as work days, use inclusive. The calculator gives you both options so you don't have to guess.