How to Calculate Byaj (Interest) at “₹ per 100 per Month” — With Examples
A simple guide to calculating interest the traditional Indian way — rate per ₹100 per month, counting days, yearly compounding and part payments — with worked examples.
The red-cloth bahi has served Indian traders for generations. It is reliable, private and familiar. So why are so many vyaparis moving to software? Mostly because of one thing: interest.
Where the paper bahi struggles
- Interest takes hours. Every party, every loan, a different rate and a different date.
- Part payments are messy. Splitting one amount across several loans by hand invites mistakes.
- One copy only. Water, fire or a lost book means lost records.
- No quick overview. “How much is out in the market today?” needs a full evening with a calculator.
What you should not lose
Good software should feel like your bahi, not replace your way of working. It should:
- Use the same interest rules — rate per ₹100 per month, both dates counted, yearly compounding.
- Keep party names and places the way you write them, even in Hindi.
- Stay private — on your own computer, not on a stranger’s server.
- Give receipts your parties can understand.
What you gain
- Open a party and see the exact amount due today.
- Receive one payment and let it be split across loans automatically.
- Print a receipt for every payment.
- See loans you have taken sorted by rate, so you repay the costliest first.
- Keep a backup copy in a second place.
How to switch without stress
- Try it with sample data first. Learn the screens before entering real parties.
- Start with running loans only. Enter the loans that are still open; close old ones in the bahi.
- Run both side by side for a month. Compare the interest on a few parties until you trust it.
- Make a weekly backup habit. Copy the backup to a pen drive or a second computer.
Vyapari Khatabook comes with sample data built in, so you can try every screen before typing a single real entry.