# তারিখে দিন যোগ বা বিয়োগ করুন

> শুরুর তারিখের নির্দিষ্ট দিন, সপ্তাহ, মাস, বছর বা কর্মদিবস আগে বা পরের তারিখ বের করুন। সপ্তাহের বার ও সরে যাওয়া ক্যালেন্ডার দিনের সংখ্যাও দেখুন।

ইন্টারঅ্যাকটিভ সংস্করণ: https://www.calcopenly.com/bn/datetime/add-subtract-days
বিষয়: তারিখ ও সময়ের ক্যালকুলেটর

Days and weeks are added to the start date's day number, a running count of days since 1 January 1970, so month lengths and leap years take care of themselves. Months and years move the month and keep the day of the month; when that day doesn't exist in the target month, the result is the month's last day, the same rule as Excel's EDATE. Business days are counted one at a time from the day after the start, stepping over the chosen weekend days.

Typical uses are due dates, return and cooling-off windows, visa and licence expiry dates and medication courses. 100 days after 15 January 2026 is Saturday, 25 April 2026, and 5 business days after Friday, 16 January 2026 is the following Friday.

Month steps can't always be undone: 31 March 2026 minus one month is 28 February, and 28 February plus one month is 28 March. Public holidays are not skipped here; the working-day deadline calculator takes a holiday list.

## ইনপুট

- **Start date**
- **Operation** (বিকল্প: Add, Subtract)
- **Amount**
- **একক** (বিকল্প: Days, Weeks, মাস, বছর, Business days)
- **Weekend** (বিকল্প: Sat–Sun, Fri–Sat, Sun only)

## ফলাফল

- Resulting date — প্রধান ফলাফল
- সপ্তাহের দিন
- Calendar days moved (days)
- End-of-month adjustment

## সূত্র

$$
N(\text{result}) = N(\text{start}) \pm n \quad (\text{days}),\qquad \text{day} = \min(d, \text{days in target month}) \quad (\text{months})
$$

## সমাধান করা উদাহরণ

### 31 January plus one month in a leap year

- Start date: 2024-01-31
- Operation: Add
- Amount: 1
- একক: মাস
- **Resulting date: 2024-02-29**
- **সপ্তাহের দিন: Thursday**
- **Calendar days moved: 29 days**
- যাচাইয়ের উৎস: Python dateutil: date(2024,1,31) + relativedelta(months=1) = 2024-02-29 (Excel EDATE agrees)

### 100 days after 15 Jan 2026

- Start date: 2026-01-15
- Operation: Add
- Amount: 100
- একক: Days
- **Resulting date: 2026-04-25**
- **সপ্তাহের দিন: Saturday**
- যাচাইয়ের উৎস: Python 3.8: date(2026,1,15) + timedelta(days=100)

### Leap day plus one year

- Start date: 2024-02-29
- Operation: Add
- Amount: 1
- একক: বছর
- **Resulting date: 2025-02-28**
- **Calendar days moved: 365 days**
- যাচাইয়ের উৎস: Python dateutil: date(2024,2,29) + relativedelta(years=1) = 2025-02-28

### 31 March minus one month

- Start date: 2026-03-31
- Operation: Subtract
- Amount: 1
- একক: মাস
- **Resulting date: 2026-02-28**
- **Calendar days moved: -31 days**
- যাচাইয়ের উৎস: Python dateutil: date(2026,3,31) − relativedelta(months=1) = 2026-02-28

### Friday plus five business days

- Start date: 2026-01-16
- Operation: Add
- Amount: 5
- একক: Business days
- Weekend: Sat–Sun
- **Resulting date: 2026-01-23**
- **সপ্তাহের দিন: Friday**
- **Calendar days moved: 7 days**
- যাচাইয়ের উৎস: numpy.busday_offset('2026-01-16', 5, roll='backward') = 2026-01-23

### Ten business days before 15 Jan 2026

- Start date: 2026-01-15
- Operation: Subtract
- Amount: 10
- একক: Business days
- Weekend: Sat–Sun
- **Resulting date: 2026-01-01**
- **Calendar days moved: -14 days**
- যাচাইয়ের উৎস: numpy.busday_offset('2026-01-15', -10, roll='forward') = 2026-01-01

## প্রশ্ন

### How do I work out the date 90 days from today?

Enter today as the start date, choose Add, type 90 and pick Days. Counting starts on the day after the start date, so 90 days from 1 January 2026 is 1 April 2026: January, February and March hold 31 + 28 + 31 = 90 days. In a leap year the same count from 1 January ends on 31 March, because February has 29 days.

### What is 31 January plus one month?

28 February, or 29 February in a leap year such as 2024. A day of the month that doesn't exist in the target month is moved back to that month's last day, which is how Excel's EDATE and Python's dateutil relativedelta behave. The same rule makes 31 March minus one month 28 February 2026, and 31 August plus one month 30 September.

### How do I add business days to a date?

Count forward from the day after the start date and skip each weekend day. Friday, 16 January 2026 plus 5 business days is Friday, 23 January, 7 calendar days later; 10 business days before 15 January 2026 is 1 January. Public holidays are not skipped in this calculator, whereas Excel's WORKDAY(start, days, holidays) skips any holidays you list.

### Is adding one year the same as adding 365 days?

Only when the year ahead has no 29 February in it. From 15 January 2027 one year later is 15 January 2028, 365 days on, but from 1 March 2027 one year later is 1 March 2028, 366 days on, because 29 February 2028 falls in between. 29 February 2024 plus one year becomes 28 February 2025 under the month-end rule.

### “তারিখে দিন যোগ বা বিয়োগ করুন” কতটা নির্ভুল?

নির্ভুলতা আপনার ইনপুট ও পদ্ধতির অনুমানের ওপর নির্ভর করে। দশমিক গণনায় 50টি সার্থক অঙ্ক ব্যবহৃত হয়, কিন্তু আনুমানিক হিসাব, সংখ্যাগত পদ্ধতি ও উৎসের তথ্য কম নির্ভুল হতে পারে; প্রদর্শিত মান রাউন্ড করলে এই সীমাবদ্ধতাগুলি দূর হয় না। স্বতন্ত্র উৎসের সমাধানের সঙ্গে যাচাই করা উদাহরণ: ৭। যেমন, “31 January plus one month in a leap year” উদাহরণটি Python dateutil: date(2024,1,31) + relativedelta(months=1) = 2024-02-29 (Excel EDATE agrees)-এর সঙ্গে যাচাই করা হয়।

### এই পদ্ধতির উৎস কী?

Howard Hinnant — chrono-compatible low-level date algorithms; Microsoft Excel EDATE and WORKDAY functions (same month-end and business-day conventions).

## উৎস

- [Howard Hinnant — chrono-compatible low-level date algorithms](https://howardhinnant.github.io/date_algorithms.html)
- [Microsoft Excel EDATE and WORKDAY functions (same month-end and business-day conventions)](https://support.microsoft.com/office/edate-function-3c920eb2-6e66-44e7-a1f5-753ae47ee4f5)