How it works
This calculator finds the gap between any two dates you provide, then breaks down the result into days, weeks, and business days. It's useful for planning projects, tracking time off, calculating contract periods, or simply answering "how long until…?" questions.
You enter a start date and end date in YYYY-MM-DD format. The calculator then:
- Counts every calendar day in between
- Divides the total into complete weeks (and remaining days)
- Counts only Monday–Friday as business days
- Optionally includes the end date itself in the count
The formula
Total days = (End date − Start date) + [1 if include end day is ON, else 0]
Business days are calculated by counting each weekday (Monday–Friday) within the date range. Weeks are derived by dividing total days by 7.
Worked example
Let's say you're planning a project that runs from 2024-11-15 (Friday) to 2024-11-29 (Friday), and you want to include the final day.
Step 1: Find the raw day difference
- End date: 2024-11-29
- Start date: 2024-11-15
- Difference: 14 days
Step 2: Add 1 because "include end day" is enabled
- 14 + 1 = 15 days total
Step 3: Break into weeks and remaining days
- 15 ÷ 7 = 2 weeks and 1 day
- Result: 2 weeks, 1 day
Step 4: Count business days
- Week 1 (Nov 15–21): Fri, Mon, Tue, Wed, Thu = 5 days
- Week 2 (Nov 22–28): Fri, Mon, Tue, Wed, Thu = 5 days
- Final day (Nov 29): Fri = 1 day
- Result: 11 business days
So your 15-calendar-day project contains 11 working days, which helps you estimate realistic timelines when weekends don't count.
Common mistakes
Forgetting to toggle the end date option: If you're counting a hotel stay or event that runs through a certain date, remember to turn on "Include end day." Otherwise you'll be one day short. For instance, a stay from Jan 1–3 should count as 3 days, not 2.
Confusing weeks with business weeks: The weeks output is simply total days ÷ 7, which includes weekends. If you need working weeks only, divide the business day count by 5 instead.
Assuming holidays are excluded: The calculator counts all weekdays equally. If you're planning around a holiday that falls on a Monday, you'll need to manually deduct it from the business day total—the tool won't know about it automatically.
Entering dates in the wrong format: Make sure to use YYYY-MM-DD (for example, 2024-12-25, not 12/25/2024 or 25-12-2024). Most browsers will guide you with a date picker, but manually typed dates must follow this format.