Calculate Days Between Dates, Add/Subtract Days & More
✓ Days Between Dates - Calculate duration in days, weeks, months, years
✓ Add/Subtract Days - Find future or past dates easily
✓ Business Days - Exclude weekends for work calculations
✓ Day of Year - Find which day number of the year
Use Case: Calculate project duration, days until event, vacation length
Days
A Date Calculator is a versatile tool that helps you perform various date-related calculations including finding the number of days between two dates, adding or subtracting days/weeks/months from a date, calculating business days, finding day of the year, and more.
Our 6-in-1 date calculator includes: days between dates, add days to date, subtract days from date, add/subtract time, day of year finder, and business days calculator!
Start Date: 1 January 2025
End Date: 9 November 2025
Result:
Start Date: 9 November 2025
Add: 90 days (3 months)
Result:
7 February 2026
Perfect for deadline calculations!
Period: 1-30 November 2025
Total Days: 30 days
Breakdown:
20 Business Days
10 Weekend Days (Sat-Sun)
Start: 10:00 AM
Add: 5 hours 30 minutes
Result:
3:30 PM
(15:30 in 24-hour format)
Days Between Dates Formula: Days = End Date - Start Date. Step-by-Step Method: Write down both dates (DD/MM/YYYY). Identify the earlier date (start) and later date (end). Calculate the difference in days. Adjust for leap years if needed. Example 1 - Same Year: Start: 1 January 2025. End: 9 November 2025. Days: January (31-1=30) + February (28) + March (31) + April (30) + May (31) + June (30) + July (31) + August (31) + September (30) + October (31) + November (9) = 312 days. Example 2 - Different Years: Start: 15 December 2024. End: 15 March 2025. Days in 2024: Dec (31-15=16). Days in 2025: Jan (31) + Feb (28) + Mar (15) = 74. Total: 16 + 74 = 90 days. Quick Mental Math Tips: Same month? Subtract dates directly (25th - 10th = 15 days). Consecutive months? Add remaining days of first month + days of second month. Full months? Count 30 days per month (rough estimate). Use online calculator for precise results! Include End Date Option: Without end date: 9 Nov - 1 Jan = 312 days. With end date included: 312 + 1 = 313 days (counts both start and end). India Context: Use for calculating: Leave duration (office/school). Project timelines. Festival gaps (Diwali to Holi). Loan tenure (EMI calculations). Visa validity periods. Common Date Ranges India: Diwali to New Year: ~45-60 days. Holi to Diwali: ~200-230 days. Financial Year (Apr 1 - Mar 31): 365 days. Quarter (3 months): ~90 days. Half year (6 months): ~180 days. Leap Year Consideration: Regular year: 365 days. Leap year (2024, 2028): 366 days (extra day in Feb). Leap years occur every 4 years (divisible by 4). Exception: Century years must be divisible by 400. Business vs Calendar Days: Calendar days: Include all days (weekends + weekdays). Business days: Exclude Saturdays and Sundays. Example: 10 calendar days might be only 6-8 business days. Real-Life Applications India: Project Management: Calculate project duration, deadline dates. Leave Planning: Count vacation days, plan trips. Finance: Calculate interest periods, loan tenure. Legal: Notice periods, contract durations. Education: Semester lengths, exam preparation time. Pro Tips: Always double-check leap years for February calculations. Use a date calculator for accuracy (avoid manual errors). Remember: 30 days hath September, April, June, and November. Count business days for work-related calculations. Include both start and end dates when calculating leave/vacation.
Adding Days to a Date: Formula: New Date = Start Date + Number of Days. Simple Method (Same Month): Start: 5 November 2025. Add: 10 days. Result: 5 + 10 = 15 November 2025. Method (Crossing Months): Start: 25 November 2025. Add: 10 days. November has 30 days: Remaining days in Nov: 30 - 25 = 5 days. Days needed in Dec: 10 - 5 = 5 days. Result: 5 December 2025. Method (Crossing Years): Start: 20 December 2025. Add: 20 days. Days in Dec: 31 - 20 = 11 days left. Days in Jan: 20 - 11 = 9 days. Result: 9 January 2026. Adding Weeks/Months/Years: 1 week = 7 days (Example: Nov 1 + 2 weeks = Nov 15). 1 month = 30 days average (Example: Jan 15 + 1 month = Feb 15). 1 year = 365 days (Example: Nov 9, 2025 + 1 year = Nov 9, 2026). Leap year = 366 days (add 1 extra day in Feb). Subtracting Days from a Date: Formula: New Date = Start Date - Number of Days. Simple Method (Same Month): Start: 15 November 2025. Subtract: 5 days. Result: 15 - 5 = 10 November 2025. Method (Crossing Months): Start: 5 November 2025. Subtract: 10 days. Days available in Nov: 5 days. Days needed from Oct: 10 - 5 = 5 days. October has 31 days: 31 - 5 = 26 October 2025. Result: 26 October 2025. Method (Crossing Years): Start: 5 January 2025. Subtract: 10 days. Days available in Jan: 5 days. Days from Dec 2024: 10 - 5 = 5 days. December has 31 days: 31 - 5 = 26 December 2024. Result: 26 December 2024. Real-World Examples India: Example 1 - Project Deadline: Today: 9 November 2025. Project duration: 45 days. Deadline: 9 Nov + 45 days = 24 December 2025. Example 2 - Advance Booking: Event date: 15 February 2026. Book 30 days in advance. Booking date: 15 Feb - 30 days = 16 January 2026. Example 3 - Notice Period: Last working day: 31 December 2025. Notice period: 30 days. Resignation date: 31 Dec - 30 days = 1 December 2025. Example 4 - Loan EMI: First EMI: 1 January 2025. 12 monthly EMIs. Last EMI: 1 Jan + (12 × 30) = 1 January 2026. Month-End Adjustments: Adding to 31st of month with 30 days: Jan 31 + 1 month = Feb 28/29 (not March 3). Jan 31 + 2 months = Mar 31 (skips Feb). Special case: Handle short months (Feb) carefully. Business Days Addition: Regular days: Include weekends. Business days: Skip Sat-Sun, add extra days. Example: Add 5 business days from Friday: Fri → Mon (1) → Tue (2) → Wed (3) → Thu (4) → Fri (5) = Next Friday. India-Specific Scenarios: Visa Processing: Apply date: 1 Nov. Processing: 15 business days. Approval: ~22 November (excluding weekends). Leave Application: Leave start: 1 Dec. Duration: 10 days. Return: 11 December. Contract Renewal: Contract end: 31 Dec 2025. Renewal: 90 days before = 2 October 2025. Festival Planning: Diwali 2025: 1 November. Shopping start: 15 days before = 17 October. Quick Reference - Days in Months: Jan (31), Feb (28/29), Mar (31), Apr (30), May (31), Jun (30), Jul (31), Aug (31), Sep (30), Oct (31), Nov (30), Dec (31). Mnemonic: "30 days hath September, April, June, and November. All the rest have 31, except February with 28/29." Pro Tips: Use online calculators for complex calculations (avoid errors). Check leap years when crossing February. Count business days for office/work-related dates. Set reminders 2-3 days before important deadlines. Plan backwards from deadline to find start date.
Business Days Definition: Business days = Working days (Monday to Friday only). Excludes: Saturdays, Sundays (weekends). Some countries also exclude public holidays. India Context: Standard work week: Monday to Friday (5 days). Weekend: Saturday and Sunday (2 days). Some offices: Saturday half-day (considered 0.5 business day). Government offices: May have different schedules. How to Calculate Business Days: Method 1 - Manual Counting: Write all dates from start to end. Cross out Saturdays and Sundays. Count remaining days = Business days. Method 2 - Formula Approach: Total days = End date - Start date. Full weeks = Total days ÷ 7. Weekend days = Full weeks × 2. Business days = Total days - Weekend days. Adjust for partial weeks (remaining days). Example 1 - Simple Calculation: Period: 1 November 2025 (Fri) to 15 November 2025 (Fri). Total days: 15 - 1 = 14 days (include both dates = 15 days). Full weeks: 15 ÷ 7 = 2 weeks (14 days). Remaining: 1 day (Friday). Weekend days: 2 weeks × 2 = 4 weekend days. Business days: 15 - 4 = 11 business days. Example 2 - Month-Long Period: Period: 1 November 2025 to 30 November 2025. Total days: 30 days. November 2025 calendar: Starts on Saturday. Saturdays: 1, 8, 15, 22, 29 (5 days). Sundays: 2, 9, 16, 23, 30 (5 days). Weekend days: 5 + 5 = 10 days. Business days: 30 - 10 = 20 business days. Example 3 - Short Period: Period: Monday to Friday (same week). Total days: 5 days. Weekend days: 0 (no weekends included). Business days: 5 business days. Business Days vs Calendar Days: 1 week: 7 calendar days = 5 business days. 2 weeks: 14 calendar days = 10 business days. 1 month (30 days): ~20-22 business days. 1 year (365 days): ~260 business days. Quick Estimation Formula: Business days ≈ (Calendar days ÷ 7) × 5. Example: 21 calendar days ÷ 7 = 3 weeks × 5 = ~15 business days. Real-World Applications India: Project Timelines: Project duration: 10 business days. Start: Monday. End: Second Friday (2 weeks later). Delivery Services: Standard delivery: 3-5 business days. Order Monday → Delivery Thursday-Monday. Banking Transactions: Cheque clearance: 2-3 business days. NEFT/RTGS: Same business day (if before cutoff). Notice Periods: Resignation notice: 30 calendar days or 20-22 business days. Termination notice: 15 business days = ~3 weeks. Legal Deadlines: Court filing: 15 business days from notice. Response time: 7 business days = ~10 calendar days. Vendor Payments: Payment terms: Net 30 business days. Roughly 6 weeks calendar days. Business Days with Holidays: National holidays reduce business days further. Example: 20 business days - 2 holidays = 18 actual working days. India Public Holidays (2025): Republic Day: 26 January (Monday). Holi: 14 March (Friday). Independence Day: 15 August (Friday). Gandhi Jayanti: 2 October (Thursday). Diwali: 1 November (Saturday - weekend already). Plus: State-specific holidays, festival leaves. Calculating with Holidays: Start with business days count. Subtract public holidays falling on weekdays. Result = Actual working days. International Business Days: USA: Monday-Friday (5 days). Europe: Monday-Friday (5 days). Middle East: Sunday-Thursday (5 days, different weekend!). Always check local work weeks for international dealings. Pro Tips for Business Days: Add 40-45% extra days to convert business days to calendar days. Use online calculators for accuracy (complex with holidays). Plan project deadlines considering weekends and holidays. For India: Assume ~22 business days per month (safe estimate). Remember: Festival seasons (Oct-Nov, Mar-Apr) have more holidays. Business Day Ranges: 1 business day: Tomorrow (if today is weekday). 2-3 business days: Within same week or early next week. 5 business days: Exactly 1 work week. 10 business days: 2 work weeks. 20 business days: Roughly 1 month. 60 business days: Roughly 3 months. Common Mistakes to Avoid: Counting weekends as business days. Forgetting public holidays. Not checking if start/end dates are weekends. Assuming 30 business days = 1 month (it's ~6 weeks!). Using calendar days for business deadlines. Quick Business Days Calculator: For any period, use: Business days ≈ Total days - (Total days ÷ 7 × 2) - Public holidays. Example: 30 days - (30÷7 × 2) - 1 holiday = 30 - 8.5 - 1 ≈ 20 business days.
Day of Year (DOY) Definition: Day of Year = Sequential number of the day in a year (1-365 or 1-366). January 1 = Day 1. December 31 = Day 365 (or 366 in leap year). Also called: Julian day, ordinal date, year day. How to Calculate Day of Year: Formula: DOY = Sum of days in all previous months + Current day of month. Step-by-Step Method: Note the date (DD/MM/YYYY). Add days in all completed months (Jan to previous month). Add current day of month. Adjust for leap year if February passed. Example 1 - Mid-Year Date: Date: 9 November 2025. Completed months: Jan (31) + Feb (28) + Mar (31) + Apr (30) + May (31) + Jun (30) + Jul (31) + Aug (31) + Sep (30) + Oct (31) = 304 days. Current month: 9 days in November. Day of Year: 304 + 9 = 313. Result: November 9, 2025 is the 313th day of 2025. Example 2 - Early Year Date: Date: 15 February 2025. Completed months: Jan (31) = 31 days. Current month: 15 days in February. Day of Year: 31 + 15 = 46. Result: February 15, 2025 is the 46th day of 2025. Example 3 - End of Year: Date: 31 December 2025. All months: Jan(31) + Feb(28) + Mar(31) + Apr(30) + May(31) + Jun(30) + Jul(31) + Aug(31) + Sep(30) + Oct(31) + Nov(30) + Dec(31) = 365. Result: December 31, 2025 is the 365th day of 2025. Leap Year Adjustment: Regular year: 365 days total. Leap year (2024, 2028): 366 days total (Feb has 29 days). Leap year rule: Divisible by 4 (except century years not divisible by 400). After Feb 29: Add 1 extra day to DOY in leap years. Example - Leap Year: Date: 9 November 2024 (leap year). Months: Jan(31) + Feb(29) + Mar(31) + Apr(30) + May(31) + Jun(30) + Jul(31) + Aug(31) + Sep(30) + Oct(31) = 305 days. Current: 9 days in Nov. Day of Year: 305 + 9 = 314 (one more than non-leap year). Quick Reference - Day of Year by Month: Jan 1: Day 1. Feb 1: Day 32 (31 + 1). Mar 1: Day 60 (31+28+1) or 61 (leap year). Apr 1: Day 91 (31+28+31+1) or 92 (leap). May 1: Day 121 or 122. Jun 1: Day 152 or 153. Jul 1: Day 182 or 183. Aug 1: Day 213 or 214. Sep 1: Day 244 or 245. Oct 1: Day 274 or 275. Nov 1: Day 305 or 306. Dec 1: Day 335 or 336. Days Remaining in Year: Formula: Days Remaining = 365 - Day of Year (366 in leap year). Example: November 9, 2025: Day 313. Remaining: 365 - 313 = 52 days left in 2025. Percentage of Year Completed: Formula: Percentage = (Day of Year ÷ Total Days) × 100. Example: Day 313 of 365: (313 ÷ 365) × 100 = 85.75% of year completed. Real-World Uses: Project Planning: Track project timelines ("due on day 200 of year"). Agriculture: Planting/harvest schedules (growing degree days). Aviation: Flight logs, maintenance schedules. Scientific Research: Data logging, experiment timelines. Astronomy: Calculate solar positions, daylight hours. Finance: Calculate daily interest, trading days. India-Specific Examples: Financial Year 2025-26: April 1, 2025 = Day 91. March 31, 2026 = Day 90 (next year). FY duration = 365 days. Important Dates 2025: Republic Day (Jan 26): Day 26. Independence Day (Aug 15): Day 227. Gandhi Jayanti (Oct 2): Day 275. Diwali (Nov 1): Day 305. New Year (Dec 31): Day 365. Festival Planning: Diwali to New Year: Days 305 to 365 = 60 days. Holi to Diwali (approx): Days 73 to 305 = 232 days. Academic Calendar: School year start (June): Day ~152. Mid-term (October): Day ~275. Year end (March): Day ~90 (next year). Reverse Calculation - Find Date from DOY: Given: Day 200 of 2025. Method: Subtract days month by month. Jan(31) → 200-31=169. Feb(28) → 169-28=141. Mar(31) → 141-31=110. Apr(30) → 110-30=80. May(31) → 80-31=49. Jun(30) → 49-30=19. Result: Day 200 = July 19, 2025. Leap Year Impact: Regular year: Day 200 = July 19. Leap year: Day 200 = July 18 (one day earlier due to Feb 29). Pro Tips: Use online calculator for instant results. Remember leap years when calculating after February. Day of year helps compare dates across different years. Useful for tracking annual goals/progress. Industries like agriculture heavily rely on DOY. Quick Milestones: Day 1: New Year. Day 100: ~April 10 (or April 9 in leap year). Day 200: ~July 19 (or July 18 in leap year). Day 300: ~October 27 (or October 26 in leap year). Day 365/366: Last day of year.
Time Calculation Basics: Time units: Hours (0-23 or 1-12), Minutes (0-59), Seconds (0-59). 24-hour format: 00:00 (midnight) to 23:59 (11:59 PM). 12-hour format: 12:00 AM (midnight) to 11:59 PM. Time zones: India uses IST (Indian Standard Time) = UTC+5:30. Adding Time - Basic Method: Formula: End Time = Start Time + Hours + Minutes. Example 1 - Same Day: Start: 10:00 AM. Add: 3 hours. Result: 10:00 + 3:00 = 13:00 (1:00 PM). Example 2 - Crossing Noon: Start: 10:30 AM. Add: 2 hours 45 minutes. Calculation: 10:30 + 2:00 = 12:30 PM. 12:30 + 0:45 = 1:15 PM. Result: 1:15 PM (13:15 in 24-hour format). Example 3 - Crossing Midnight: Start: 10:00 PM (22:00). Add: 5 hours. Calculation: 22:00 + 5:00 = 27:00. Adjust: 27:00 - 24:00 = 03:00 (3:00 AM next day). Result: 3:00 AM (next day). Adding Minutes with Overflow: Example: Start: 10:45 AM. Add: 30 minutes. Calculation: 45 + 30 = 75 minutes. Convert: 75 minutes = 1 hour 15 minutes. Result: 10:45 + 1:15 = 12:00 PM (noon). Subtracting Time: Formula: End Time = Start Time - Hours - Minutes. Example 1 - Same Day: Start: 3:00 PM (15:00). Subtract: 2 hours. Result: 15:00 - 2:00 = 13:00 (1:00 PM). Example 2 - Crossing Midnight: Start: 1:00 AM (01:00). Subtract: 3 hours. Calculation: 01:00 - 3:00 = -2:00. Adjust: 24:00 - 2:00 = 22:00 (10:00 PM previous day). Result: 10:00 PM (previous day). Time Difference Between Two Times: Formula: Difference = End Time - Start Time. Example 1 - Same Day: Start: 9:00 AM. End: 5:00 PM (17:00). Difference: 17:00 - 9:00 = 8 hours. Result: 8 hours working time. Example 2 - Overnight: Start: 11:00 PM (23:00). End: 3:00 AM next day (03:00). Calculation: Until midnight: 24:00 - 23:00 = 1 hour. After midnight: 03:00 = 3 hours. Total: 1 + 3 = 4 hours. Result: 4 hours. Real-World Examples India: Office Hours: Start: 9:00 AM. End: 6:00 PM (18:00). Working hours: 18:00 - 9:00 = 9 hours. Lunch break: 1 hour. Net work: 9 - 1 = 8 hours. Flight Time: Departure: 6:30 AM from Delhi. Duration: 2 hours 30 minutes. Arrival: 6:30 + 2:30 = 9:00 AM in Mumbai. Meeting Schedule: Meeting: 11:00 AM. Duration: 1 hour 45 minutes. End: 11:00 + 1:45 = 12:45 PM. Exam Duration: Start: 2:00 PM (14:00). Duration: 3 hours. End: 14:00 + 3:00 = 17:00 (5:00 PM). Movie Show: Show start: 7:30 PM (19:30). Movie length: 2 hours 40 minutes. End: 19:30 + 2:40 = 22:10 (10:10 PM). International Time Zones: India (IST): UTC+5:30. USA (EST): UTC-5 (10.5 hours behind India). UK (GMT): UTC+0 (5.5 hours behind India). Dubai (GST): UTC+4 (1.5 hours behind India). Australia (AEST): UTC+10 (4.5 hours ahead India). Example - International Call: India time: 10:00 AM (IST). USA (EST): 10:00 - 10:30 = 23:30 previous day (11:30 PM). UK (GMT): 10:00 - 5:30 = 04:30 (4:30 AM). Time Conversion Tips: IST to USA EST: Subtract 10.5 hours. IST to UK GMT: Subtract 5.5 hours. IST to Dubai GST: Subtract 1.5 hours. Always check for daylight saving time changes! Working Hours Calculation: Formula: Work Hours = (End Time - Start Time) - Breaks. Example: Shift: 9:00 AM to 6:00 PM. Breaks: 1 hour lunch + 2×15 min tea = 1.5 hours. Work: 9 hours - 1.5 hours = 7.5 hours. Night Shift: Shift: 11:00 PM to 7:00 AM. Duration: 24:00-23:00 + 7:00 = 1 + 7 = 8 hours. Overtime Calculation: Regular shift: 9:00 AM to 6:00 PM (9 hours incl. 1hr break). Overtime: Work till 9:00 PM. Extra hours: 21:00 - 18:00 = 3 hours overtime. Travel Time Calculation: Leave home: 8:00 AM. Commute: 45 minutes. Office arrival: 8:00 + 0:45 = 8:45 AM. Project Deadline Time: Project due: 5:00 PM today. Current time: 2:30 PM. Time left: 17:00 - 14:30 = 2 hours 30 minutes. Pro Tips: Use 24-hour format for clarity (avoid AM/PM confusion). Account for time zones in international communication. Add buffer time (15-30 minutes) for important appointments. Set alarms/reminders 15 minutes before meetings. Check daylight saving time (DST) for international calls. India doesn't observe DST, but many countries do. Common Time Intervals India: Breakfast: 8:00-10:00 AM. Lunch: 12:30-2:00 PM. Tea break: 4:00-5:00 PM. Dinner: 8:00-10:00 PM. Office hours: 9:00 AM - 6:00 PM. Quick Mental Math: Adding 30 minutes: Move minute hand to "6" (half circle). Adding 1 hour: Same minutes, next hour. Adding 15 minutes: Move minute hand one quarter (15→30→45→00). Subtracting 30 minutes: Move back one half circle. Time Duration Shortcuts: 1 hour = 60 minutes. Half hour = 30 minutes. Quarter hour = 15 minutes. 1 day = 24 hours. 1 week = 168 hours (24 × 7).
Calendar Days vs Working Days: Calendar Days (Total Days): Definition: All consecutive days including weekends and holidays. Count: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday. Example: 7 consecutive days = 7 calendar days. Working Days (Business Days): Definition: Only weekdays, excluding weekends and public holidays. Count: Monday to Friday only (exclude Sat-Sun). Example: 7 consecutive days = 5 working days (Mon-Fri). Key Differences Table: Calendar Days: Include weekends: Yes. Include holidays: Yes. Days per week: 7 days. Days per month: ~30 days. Days per year: 365/366 days. Working Days: Include weekends: No (exclude Sat-Sun). Include holidays: No (exclude public holidays). Days per week: 5 days (Mon-Fri). Days per month: ~20-22 days. Days per year: ~260 days. Conversion Formula: Working days ≈ Calendar days × 5/7 (rough estimate). More accurate: (Calendar days ÷ 7 × 5) - Holidays. Example 1 - One Month: Calendar days (November): 30 days. Working days (Nov 2025): Saturdays: 1,8,15,22,29 (5 days). Sundays: 2,9,16,23,30 (5 days). Working days: 30 - 10 = 20 business days. Example 2 - Three Months: Calendar days (Jan-Mar): 31+28+31 = 90 days. Full weeks: 90 ÷ 7 ≈ 12.8 weeks. Weekend days: 12.8 × 2 ≈ 26 days. Working days: 90 - 26 = ~64 days (excluding holidays). Example 3 - One Year: Calendar days (2025): 365 days. Weekends: 52 weeks × 2 = 104 days. Public holidays India: ~10-12 days (weekday holidays). Working days: 365 - 104 - 12 = ~249 business days. Typical: 250-260 working days per year. When to Use Calendar Days: Personal Planning: Vacation duration, trip length. Age calculation (days old). Event countdown (days until birthday). Medical: Medication duration (take for 7 calendar days). Pregnancy tracking (40 weeks = 280 calendar days). Legal (some cases): Contract duration if specified as "calendar days". Rental agreements (monthly = 30 calendar days). Financial: Interest calculation (daily compounding). Credit card due dates (30 calendar days). When to Use Working Days: Office/Work: Leave application (5 working days leave). Notice period (30 working days). Project timelines (project due in 10 business days). Delivery Services: Standard shipping: 3-5 business days. Express delivery: 1-2 business days. Banking: Cheque clearance: 2-3 working days. Loan processing: 7-10 business days. Legal: Court notices: 15 working days to respond. Legal filing deadlines: Often in business days. Government: Passport processing: 10-15 working days. License renewal: 7 working days. Real-World Examples India: Example 1 - Leave Application: Leave duration: 5 working days (Mon-Fri). Calendar days: 5 days (if no weekend) or 7 days (if includes weekend). Submit request: 7 calendar days in advance. Example 2 - Project Deadline: Project timeline: 20 working days. Start: Monday, Nov 1. Working days: Nov 1-30 has ~20 business days. End: Approximately Nov 30 (Friday). Calendar days: 30 calendar days. Example 3 - Delivery Time: Order date: Monday. Delivery: 3-5 business days. Expected: Thursday-Monday (3-5 working days). Calendar days: 3-7 calendar days (depending on weekend). Example 4 - Bank Transfer: Transfer initiation: Friday 6:00 PM. Processing: 2 business days. Credit date: Tuesday (skips Sat-Sun). Calendar days: 4 calendar days (Fri-Tue). India Public Holidays Impact: National holidays (2025): Republic Day: Jan 26. Holi: March 14. Independence Day: Aug 15. Gandhi Jayanti: Oct 2. Diwali: Nov 1 (falls on Sat, so no impact). State holidays: Vary by state (Ugadi, Pongal, Onam, etc.). Total holidays: 10-12 national + 3-5 state = ~15 holidays/year. Calculation with Holidays: 30 calendar days = 30 days. Weekend days: ~8-9 days (4 weekends). Holidays: ~1-2 weekdays. Working days: 30 - 9 - 2 = ~19 business days. Pro Tips: Always clarify: "calendar days" or "working days" in contracts. Business communications default to working days. Banking/legal often use working days. Add 40-50% when converting working to calendar days (safe buffer). Plan ahead: 30 working days ≈ 6 weeks calendar time. Check company/country-specific working day definitions. Common Mistakes to Avoid: Assuming 30 calendar days = 30 working days (it's only ~22). Not excluding public holidays from working days. Counting weekend days in business timelines. Using calendar days for notice periods (usually working days). Not verifying weekend days (some weeks have holidays). Quick Reference Conversion: 5 working days = 7 calendar days (1 week). 10 working days = 14 calendar days (2 weeks). 20 working days = 28-30 calendar days (~1 month). 60 working days = 84-90 calendar days (~3 months). 250 working days = 365 calendar days (1 year). International Differences: India: Mon-Fri (5 days work week). Middle East: Sun-Thu (5 days, different weekend!). Some countries: Sat half-day (5.5 days work week). Always check local working week for international dealings! Industry Standards: IT/Corporate: Strictly Mon-Fri working days. Government: Mon-Fri, some Sat half-day. Healthcare: 24/7, but admin follows Mon-Fri. Retail/Services: May include Sat-Sun (6-7 day weeks). Check your industry standards before calculating!