See the effect of a part-payment against your outstanding loan balance.
Works exactly like a one-time prepayment against your current outstanding balance.
Interest saved: Original total interest − new total interest after the part-payment
The loan part-payment calculator is built for a loan that is already running. You enter today's outstanding balance, the remaining tenure and the rate, plus the lump sum you want to pay now. It keeps your EMI the same and shows how many fewer months you will pay and how much interest you save from this point on.
Most borrowers do not know their original loan terms by heart, but their bank statement or app shows the principal outstanding and the months left. Using those current figures gives a far more realistic answer than plugging in the original loan amount, because much of the early interest has already been paid and cannot be saved.
It suits anyone who receives occasional lump sums, such as an arrears payment, an incentive or a matured policy, and wants to see what one part-payment achieves on the existing loan.
1. From your loan statement, note the outstanding principal B, the remaining tenure m in months and the current rate.
2. Compute the EMI that clears B over m months: EMI = B × r × (1 + r)ᵐ ÷ ((1 + r)ᵐ − 1), with r = annual rate ÷ 12 ÷ 100. It should be close to your actual EMI.
3. Find the interest still due without part-payment: EMI × m − B.
4. Subtract the part-payment from B.
5. Repeat month by month: interest = balance × r, balance falls by EMI − interest, until the balance reaches zero.
6. Add the interest charged in this new schedule and compare it with the earlier figure to get interest saved.
Interest already paid is gone and no action today can bring it back. What a part-payment changes is only the future: the interest that would have been charged on the balance from now until the end. That future interest depends on today's balance, the remaining months and the rate, not on the original loan amount. Treating the running loan as a fresh loan of the outstanding amount over the remaining tenure is exactly equivalent, because an amortising loan at any point is just a new loan of its balance.
The words are often used for the same thing. In practice, prepayment tends to mean clearing the whole loan or making a large payment, while part-payment means paying off a portion while the loan continues. The maths is identical. This site's prepayment calculator assumes the lump sum is paid on day one of a new loan, while this calculator applies it to today's balance on a running loan. Using the right one avoids overstating the saving from a payment made midway.
One large payment and a series of smaller ones can have similar effects if the total amount is similar and the timing is early. Many borrowers make a part-payment every year from their bonus. Each payment cuts the balance, and because the EMI is unchanged, each also increases the principal share of every later EMI. You can model a series by running this calculator repeatedly, each time using the new balance and remaining months after the previous part-payment.
Sanjay's home loan statement shows ₹18,00,000 outstanding with 144 months left at 9% a year, and he wants to part-pay ₹2,00,000 from his annual incentive.
Answer: Interest saved ₹3,33,346; Tenure reduced by 26 months
Entering the original sanctioned loan amount instead of today's outstanding balance.
Using the original tenure instead of the months that remain.
Not asking the bank to apply the payment to principal, so it sits as an advance EMI instead.
Accepting a lower EMI after part-payment without comparing the interest saved under each option.
Deciding how to use an annual bonus or incentive on a running home loan.
Planning a yearly part-payment routine and tracking its effect.
Checking the revised tenure the bank shows after a part-payment.
Comparing part-paying the home loan with clearing a smaller, costlier loan first.
What's the difference between prepayment and part-payment?
They mean the same thing — paying extra towards your loan, outside your normal EMI. 'Part-payment' is just the more common term used once a loan is already running.