Date Calculator - Days Between Dates & Business Day Counter
📅 Planning & Productivity

Date Calculator & Day Counter

The ultimate time planning tool. Calculate the exact duration between two dates or determine a future deadline by adding days, weeks, and months.

Time Engine

Select your calculation mode below.

🎛️ I want to...
🏁 Start Date
🛑 End Date
TOTAL DURATION
0 Days
0 weeks, 0 days
🏢
Business Days 0 (Mon-Fri)
🕒
In Hours 0
Detailed Breakdown:
0 Years, 0 Months, 0 Days

How to Calculate Date Differences

Calculating the exact time between two dates involves more than just subtraction. You need to account for varying month lengths (28, 30, or 31 days) and Leap Years.

1

The "Count"

By default, calculators usually subtract Start Date from End Date. This counts the "nights" between dates, not the total days touched.

2

Inclusive vs Exclusive

If you want to count both the first day and the last day (e.g., for a vacation itinerary), check the "Include End Date" box to add +1 day.

3

Business Days

This excludes weekends (Saturday & Sunday). It's essential for project deadlines and shipping estimates.

The Tricky Math: Leap Years

🐸
What is it?

Every 4 years, February gets an extra day (29th). This keeps our calendar in sync with the Earth's orbit.

➗
The Rule

A year is a leap year if it is divisible by 4, EXCEPT if it is divisible by 100 (unless also divisible by 400).

📅
Impact

If your date range crosses Feb 29th, the calculator automatically adds that extra day to the total count.

Common Uses for Date Calculations

👶

Age Calculation

Find out exactly how many days, weeks, or months old you are. Or calculate a baby's age in weeks.

🤰

Pregnancy Due Date

Add 280 days (40 weeks) to the first day of the last period to estimate the due date.

💼

Project Deadlines

"Start + 90 days." Use the Add/Subtract mode to find the exact deadline date, skipping the manual counting.

Related Planning Tools

🎂 Age Calculator → ⏱️ Time Calculator → 💼 Work Hours Calc → 📈 ROI Calculator →

Frequently Asked Questions

Does this calculate business days?
Yes. In the "Count Days" mode, the result breakdown includes a "Business Days" count, which automatically excludes Saturdays and Sundays.
What happens if I cross a time zone?
This calculator uses your local browser time to define dates. It calculates full calendar days, so time zones typically do not affect the duration unless you are calculating specific hours.
How accurate is the "Months" calculation?
Very accurate. It calculates full calendar months first, then remaining days. For example, Jan 15 to Feb 14 is "0 Months, 30 Days", but Jan 15 to Feb 15 is "1 Month, 0 Days".
Why is the result 1 day less than I expected?
Standard date math calculates the difference (End - Start). If you want to include the final day in your count (e.g., for a 3-day conference), check the "Include End Date" box.
Does it handle leap years correctly?
Yes. The logic uses the JavaScript Date object which has a built-in calendar aware of leap years (2024, 2028, etc.).
Can I calculate past dates?
Yes. If you subtract days from today, or enter an End Date before the Start Date, the calculator will show you the past date or duration.
What is the "Day of Year"?
This is a number from 1 to 365 (or 366). January 1st is Day 1. December 31st is Day 365.
How do I calculate 90 days from today?
Switch to "Add/Subtract" mode. Enter today's date, ensure "Add (+)" is selected, enter "90" in the Days field, and the result will appear instantly.
Is this useful for visa 90/180 rule?
Yes. You can use this to calculate exactly when your 90-day visa limit expires by adding 90 days to your entry date.
Does it include public holidays?
No. Public holidays vary by country and region. The "Business Days" count strictly removes weekends (Sat/Sun). You must manually subtract holidays.