Prepayment reduces the balance on which future interest is charged. Savings depend on rate, timing, remaining term, fees and whether the lender reduces the payment or the term. A savings table without those assumptions cannot be reproduced.
First-month example
For principal 100,000 at 6% nominal annual interest, monthly interest is 500. If the payment is 1,000, only 500 reduces principal. An extra 2,000 principal payment leaves 97,500 instead of 99,500. With an unchanged rate, next-month interest becomes 487.50 instead of 497.50.
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Use the Home Loan EMI Calculator for a baseline, then change only a supported prepayment assumption. Record the date, payment, rate and remaining term. Holding the payment fixed differs from recalculating it after prepayment.
An unchanged rate is an assumption, not a lender commitment. Include prepayment charges and verify the lender’s allocation rules. The month above explains the mechanism; it is not a quoted lifetime saving for an unspecified loan.