Formula
EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)balance after k EMIs = P(1 + r)ᵏ − EMI × ((1 + r)ᵏ − 1) ÷ rnew balance = balance − prepayment
- r — monthly rate
- n — total months
- The schedule is then recalculated with either the same EMI or the same remaining months
A prepayment reduces the principal, so all later interest is charged on a smaller balance.
Worked example
30,00,000 at 8.5% for 20 years; prepay 3,00,000 after 24 EMIs
- Original loan amount
- 3,000,000
- Interest rate per year
- 8.5 %
- Loan tenure
- 20
- Tenure in
- Years
- One-time prepayment amount
- 300,000
- EMIs already paid when you prepay
- 24
- Use the prepayment to
- Shorten the loan (keep the EMI)
- Currency symbol
- ₹ Rupee (INR)
Interest saved
₹8,74,379.59
New loan tenure: 16 years 3 months
Time saved: 3 years 9 months
Outstanding principal before prepaying: ₹28,75,308.65
How it works
When you prepay part of a loan, the money goes straight to principal, so every later month's interest is charged on a lower balance. There are two ways to benefit: keep paying the same EMI and finish earlier, which saves the most interest, or keep the original end date and pay a lower EMI, which helps monthly cash flow.
The tool builds the exact month-by-month schedule in whole paise, in the same way as the EMI calculator, applies your prepayment after the number of EMIs you choose, and compares total interest with and without it. It reports the interest saved, the new tenure or EMI, and the balance before and after. Prepaying earlier saves much more than prepaying late, because the balance, and therefore the interest, is highest at the start.
Many lenders charge a fee on prepayment for some loans, and rules differ between fixed and floating rates, so check your loan agreement. The EMI Calculator shows the original loan, the Amortization Schedule Calculator handles a regular extra payment every month, and the Loan Interest Rate Calculator finds the rate if you know the EMI.
Assumptions and limits
- Fixed interest rate, equal monthly instalments, reducing balance.
- No prepayment charge or processing fee; lenders often differ.
- Only one prepayment is modelled; use the amortization calculator for regular extra payments.