Weeks Between Dates
Calculate the number of weeks between any two dates.
📘 How It Works
Date Difference in Milliseconds
The calculator first computes the absolute difference between the two dates in milliseconds: |endDate - startDate|. Using absolute value ensures a positive result regardless of date order.
Convert to Days
Milliseconds are converted to days by dividing by 86,400,000 (the number of milliseconds in a day: 1000 × 60 × 60 × 24). The result is floored to get complete days.
Calculate Complete Weeks
Total days are divided by 7 to get complete weeks: weeks = Math.floor(days / 7). This gives the number of full 7-day periods between the dates.
Calculate Remaining Days
The modulo operator extracts remaining days: remainingDays = days % 7. This shows how many extra days beyond complete weeks, ranging from 0 to 6.
Result Presentation
Results are displayed as both complete weeks and the full breakdown (X weeks and Y days), plus the total day count for reference. This provides multiple perspectives on the duration.
💡 Common Use Cases
Pregnancy Tracking
Medical professionals and expecting parents track pregnancy progress in weeks. Calculate weeks since conception or weeks until due date.
Sprint & Agile Planning
Development teams often work in 1-2 week sprints. Calculate how many sprints fit between project start and deadline dates.
Fitness Program Duration
Workout and diet programs are often designed in weekly cycles. Determine how many weeks your fitness program will run.
Rental & Lease Calculations
Some rentals (vacation homes, equipment) are priced weekly. Calculate total weeks for accurate billing.
Academic Term Planning
Semester and term lengths are often measured in weeks. Calculate teaching weeks for curriculum planning.
Recovery & Treatment Duration
Medical treatments and recovery periods are frequently measured in weeks. Track progress through rehabilitation programs.