Scenario 1
Project timeline
Start: Jan 1, 2025 → End: Mar 31, 2025 = 89 days, 12.7 weeks.
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Date Difference Calculator
Find out exactly how many days between any two dates.
Adjust your inputs
Results update instantly as you type or drag.
1,900 – 2,100
1 – 12
1 – 31
1,900 – 2,100
1 – 12
1 – 31
Quick insights
Weeks
52
Approximate months
12
Quick answer
How do you calculate days between two dates?
Convert both dates to a number (milliseconds since epoch), subtract, and divide by 86,400,000 (ms per day).
How it works
From inputs to result in four steps
A quick walkthrough of what this calculator does behind the scenes.
- 1
Enter the start date (year, month, day).
- 2
Enter the end date.
- 3
See the difference in days, weeks, and months.
Formula
The math behind the number
No black box — here's exactly how the result is computed.
Formula
Diff ms = end.getTime() − start.getTime()
Days = Diff ms ÷ (1000 × 60 × 60 × 24)
Weeks = Days ÷ 7
Months ≈ Days ÷ 30.44Examples
Real-world scenarios
See how the numbers play out for typical use cases.
Scenario 2
Contract duration
Start: Jun 1, 2024 → End: Jun 1, 2025 = 366 days (leap year), 12 months.
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