Why Nepali Date Calculations Are Hard
The Bikram Sambat (BS) calendar — Nepal's official calendar — doesn't work like the Gregorian calendar you use every day:
- Variable month lengths: Baisakh (30/31), Jestha (31/32), Asar (31/32), Shrawan (31/32), Bhadra (31/32), Aswin (30), Kartik (30), Mangsir (30), Poush (29/30), Magh (30), Falgun (29/30), Chaitra (30/31). Some months have 32 days!
- Year offset: BS 2000 started on April 14, 1943 AD — not January 1. A simple +567-year offset fails for most dates.
- No fixed leap-year rule: Leap days shift based on astronomical observations, not a formula.
That's why subtracting two BS dates manually (or with a simple +567 offset) gives wrong results. Our calculator uses the actual BS calendar data (BS 2000–2090) — month-by-month day counts from the official calendar — so every calculation is calendar-accurate.
What This Calculator Does
1. Date Difference (Years, Months, Days)
Pick any two dates — both in BS, both in AD, or mixed — and get the exact duration broken down into years, months, days, plus total days, weeks, and months. The math borrows days from the previous month using that month's actual length (e.g., 32 days for Asar, 29 for Poush).
2. BS ↔ AD Conversion (Side-by-Side)
Every result shows both calendars simultaneously. Select BS 2081 Ashwin 1 and you'll see September 17, 2024 AD instantly. No separate converter needed.
3. Loan Tenure Tracking (3 Modes)
| Mode | What it calculates | Use case |
|---|---|---|
| Elapsed | Time passed since loan start | How much of my 15-year home loan is done? |
| Remaining | Time left until maturity | How many years/months left on my vehicle loan? |
| End Date | Maturity date from start + tenure | When does my 10-year personal loan end? |
4. Service Tenure & Contract Duration
Same exact math — just labeled for employment (joining date to today) or contracts (start to end date). Perfect for HR, project managers, and rental agreements.
5. PDF & Excel Export
One click downloads a branded PDF report (with tables, headers, footers, page numbers) or a structured Excel file (all fields in clean columns). Great for loan files, HR records, or sharing with your bank.
Worked Examples
Example 1: Home Loan Elapsed Tenure
Scenario: You took a 20-year home loan on BS 2078 Shrawan 15 (July 30, 2021 AD). Today is BS 2081 Ashwin 1 (Sept 17, 2024 AD). How much tenure has elapsed?
- Open calculator → Mode: Loan Tenure
- Start date: BS 2078 Shrawan 15
- End date: BS 2081 Ashwin 1 (or tap Today)
- Original tenure: 20 Years
- Result: 3 Years, 2 Months, 16 Days elapsed — 16 Years, 9 Months, 14 Days remaining
Example 2: Vehicle Loan End Date
Scenario: 7-year bike loan started on BS 2080 Magh 1 (Jan 14, 2024 AD). When does it mature?
- Mode: Loan Tenure → End Date
- Start: BS 2080 Magh 1
- Tenure: 7 Years
- Result: BS 2087 Magh 1 (Jan 14, 2031 AD)
Example 3: Employment Duration
Scenario: Joined on BS 2075 Baisakh 1 (April 14, 2018 AD). Today's date. How long have you worked?
- Mode: Service Tenure
- Start: BS 2075 Baisakh 1
- End: Tap Today
- Result: Exact years, months, days of service
How It Works (Under the Hood)
Real Calendar Data, Not Approximations
The calculator embeds the nepali-date-converter library with complete calendar data for BS 2000–2090. This includes the exact day count for every month of every year — no 30-day assumptions, no fixed offsets.
Duration Algorithm
- Convert both dates to a common internal representation
- Subtract days first; if negative, borrow from the previous month using that month's actual length
- Subtract months; if negative, borrow 12 months from the year
- Output the final Y/M/D breakdown
This mirrors how banks in Nepal calculate loan tenure — by calendar months, not 30-day chunks.