Enter the money lent and each part payment with its date. On every payment day the byaj due so far is cleared first, and only the rest cuts the principal. ₹1,00,000 lent at ₹2 sekda on 1 Jan 2026, ₹20,000 repaid on 1 May: ₹8,000 goes to byaj and ₹12,000 to principal, leaving ₹88,000.
How interest is calculated on part payments
On each payment day the calculator works out the byaj since the last payment, adds any byaj left unpaid from before, and takes the payment off that total first. This is the usual rule in a bahi khata and in Indian courts, unless the two sides agreed otherwise (why interest comes first).
- Payment less than the byaj due: all of it goes to byaj. The principal stays the same and the rest of the byaj stays due.
- Payment more than the byaj due: the byaj is cleared and the balance cuts the principal. From that day byaj runs on the smaller principal.
Byaj due = unpaid byaj + principal × sekda × months ÷ 100
Months are whole calendar months since the last payment, plus leftover days at 1/30 of a month.
| Date | Paid | Byaj due | To byaj | To principal | Principal left |
|---|---|---|---|---|---|
| 15 Feb | ₹1,500 | ₹2,933.33 | ₹1,500 | ₹0 | ₹1,00,000 |
| 1 May | ₹20,000 | ₹6,500 | ₹6,500 | ₹13,500 | ₹86,500 |
Udhar ka hisab: more money lent later
Each amount earns byaj from its own date. Say ₹50,000 was lent on 1 Jan, another ₹25,000 on 1 Apr, and ₹30,000 came back on 1 Jul. Byaj by then is ₹6,000 on the first amount plus ₹1,500 on the second, ₹7,500 in all. The payment clears that and cuts the principal by ₹22,500, to ₹52,500.
The same works for a loan to a friend or relative, a shopkeeper’s udhar, or any khata with one person where money goes both ways.
Try it in the calculatorOpen the example with more money lent laterWhy a bank’s part payment calculator shows something else
Bank prepayment calculators are built for EMI loans. Each EMI already pays that month’s interest, so an extra payment goes straight to the principal and the tool shows a shorter loan or a smaller EMI. A loan at sekda has no EMIs: byaj builds up between payments, so a payment clears it first. For EMI loans use the EMI calculator.
Simple or compound byaj?
By default byaj is simple: unpaid byaj is carried forward but earns nothing. If your agreement adds byaj to the principal every month, quarter, half-year or year, choose that under More options. The statement then shows each "added to the principal" line. See simple vs compound interest.
The damdupat warning
When unpaid byaj reaches 80% of the principal the calculator warns you, and again when it reaches the principal. On ₹50,000 at ₹2 sekda with nothing paid back, that is ₹40,000 after 40 months and ₹50,000 after 50 months. Some state laws cap the byaj a court will award at the principal: see the damdupat rule.
Keep a written record of each payment
Note the date, the amount, and how it was split between byaj and principal, and have the person paying sign it. The part payment guide has a receipt format. Print this calculator’s statement and keep it with the receipt, so the working is on paper too.
6 short answersUdhar with part payments: quick answers
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Can I add several payments, or more money lent later?
Yes. Add one line for every amount lent and every payment, each with its date, up to 40 lines. Each amount lent earns byaj from its own date, and each payment clears the byaj due before it cuts the principal. In the example above, ₹50,000 and ₹25,000 lent at different times had ₹7,500 of byaj due by 1 Jul.
What happens if a payment is less than the byaj due?
All of it goes to byaj, the principal stays the same, and the rest of the byaj stays due. In the opening example, ₹1,500 paid on 15 Feb against ₹2,933.33 of byaj left ₹1,433.33 unpaid. The next payment clears that first.
Does unpaid byaj earn byaj in this calculator?
Not unless you choose compounding. With simple interest, the default, unpaid byaj is carried forward but byaj is charged only on the principal. Under More options you can add unpaid byaj to the principal every month, quarter, half-year or year, and the statement shows each time it was added.
How do I share or print the hisaab?
Tap Share on WhatsApp to send a short summary with a link, or Copy link. The link carries every entry, so it opens the same statement on any phone. Print / PDF prints the statement alone. Nothing is stored on our side: the entries live only in the link and your browser.
Can the borrower use this calculator too?
Yes. Enter the money received as "Lent" and each repayment as "Paid back"; the maths is the same from either side. If the two sides get different numbers, compare the rate, the dates and whether byaj is simple or compound. Sharing the link puts both on the same statement.
Can I use it for shop credit or a gold loan?
Yes, for any loan with a fixed rate and dated payments: shop udhar, a loan to a friend, or a girvi loan from a moneylender, at ₹ sekda or % a year. A bank or finance company may count days or add charges in its own way, so check its statement for those. For EMI loans use the EMI calculator.
Every figure comes from one tested engine and is exact to the paisa. How we calculate