📊 Date Duration Calculator
Select dates to calculate duration
➕ Add/Subtract Time
Enter a date and operation to see result
🏢 Working Days Calculator
Number of working daysEnter dates to find working days
🎂 Age Calculator
Leave empty to use today's dateEnter a birth date to calculate age
📚 Understanding Date & Time Calculations
Master date arithmetic, duration calculations, and time management
Date Duration Calculations
Duration is the length of time between two dates. Common uses include:
- Project timelines: Calculate project duration
- Lease periods: Track rental agreements
- Employee tenure: Calculate years of service
- Event planning: Plan event schedules
- Financial calculations: Interest periods, investment terms
- Travel planning: Trip duration and itineraries
Date Arithmetic Operations
Add or subtract time from dates for scheduling and planning:
Add 5 days → Future date planning
Subtract 2 weeks → Historical dates
Add 3 months → Contract renewal dates
Add 1 year → Anniversary dates
Supports years, months, weeks, days, hours, minutes, and seconds.
Working Days Calculator
Calculate business days excluding weekends (and optionally holidays):
- Project deadlines: Calculate realistic timelines
- Delivery estimates: Business-based shipping times
- Processing times: Loan approvals, applications
- Service levels: Support ticket response times
- Leave planning: Calculate available work days
Age & Time Since Calculation
Calculate exact age and time elapsed since a specific date:
- Age verification: Legal and eligibility checks
- Milestones: Track life or business anniversaries
- Relative dates: "Time since" calculations
- Event planning: Special occasion tracking
- Insurance calculations: Age-based premiums
Date Formats & Standards
Understanding common date formats and standards:
ISO 8601: 2026-01-27 (YYYY-MM-DD)
US Format: 01/27/2026 (MM/DD/YYYY)
EU Format: 27/01/2026 (DD/MM/YYYY)
Unix Timestamp: Seconds since 1970-01-01
This calculator uses ISO 8601 format for consistency.
Leap Years & Special Cases
Important calendar considerations:
Leap Year: Every 4 years (366 days)
- Divisible by 4 = Leap year
- Divisible by 100 = NOT a leap year
- Divisible by 400 = IS a leap year
Examples: 2024 (leap), 2000 (leap), 1900 (not leap)
Common Use Cases & Examples
🏢 Business Applications
- Project timeline planning
- Delivery date calculations
- Employee tenure tracking
- Contract renewal reminders
- Invoice due date calculation
- Warranty expiration tracking
👤 Personal Applications
- Age and milestone tracking
- Event countdown timers
- Travel planning and duration
- Relationship anniversaries
- Birthday and holiday tracking
- Fitness and diet duration
💰 Financial Applications
- Interest calculation periods
- Loan maturity dates
- Investment return periods
- Payment schedule generation
- Subscription renewal dates
📋 Administrative
- License and permit renewals
- Policy expiration tracking
- Deadline management
- Schedule coordination
- Compliance tracking
Tips & Best Practices
✅ Do's
- Use consistent date formats
- Account for time zones in global contexts
- Verify leap year calculations
- Consider weekends for business calculations
- Document date conventions used
- Plan ahead for daylight saving time changes
⚠️ Don'ts
- Don't mix date formats inconsistently
- Don't assume all months have 30 days
- Don't forget about leap years
- Don't ignore time zone differences
- Don't overlook year boundaries
- Don't round approximations without noting
Related Tools
⏰ Epoch Converter
Convert Unix timestamps to readable dates and vice versa.
🌍 Timezone Calculator
Calculate time differences across multiple time zones.
📅 Calendar Tools
View full calendar grids and event scheduling tools.