An amortization schedule is simply a month-by-month table showing, for every payment across the life of a loan: the opening balance, how much of that payment goes to interest, how much goes to principal, and the closing balance after that payment. It's the full "under the hood" view of how a loan actually gets paid off - and understanding it makes it much clearer why prepayment timing matters so much.
Why the interest/principal split isn't constant
Each month, interest is calculated fresh on whatever principal you currently owe. Early in a loan, that balance is at its largest, so the interest portion of your EMI is also at its largest - often the majority of the payment in the first several years of a long-term loan like a home loan. As each payment chips away at the balance, the interest owed the following month is slightly smaller, which means slightly more of the next EMI goes towards principal instead. This effect compounds: by the final years of the loan, almost the entire EMI goes towards principal, with only a small interest component remaining.
A simplified illustration
Imagine a 20-year home loan. In year 1, a typical EMI might be split roughly 80% interest and 20% principal. By year 10 (the midpoint), that might shift to something closer to 55% interest and 45% principal. By year 19, it could flip to roughly 10% interest and 90% principal. The exact numbers depend entirely on your specific rate and tenure, but the shape of this curve - heavily interest-weighted early, heavily principal-weighted late - is a near-universal feature of amortizing loans.
Why this matters for prepayment
Because so much of your interest cost is concentrated in the early years of a loan, a prepayment made early removes principal from a balance that would otherwise have been accruing a large interest charge for many years to come. The exact same prepayment amount made in the loan's final years has far less effect, because the balance remaining by then is small and would only have accrued a little more interest anyway. This is the mathematical reason behind the general advice to prepay as early as you reasonably can - see our guide on how loan prepayment works for more on the mechanics.
How to read your own schedule
Our amortization schedule shows this month-by-month for your own loan, with and without a prepayment applied, so you can see exactly when the opening balance, interest and principal split shift - and how a prepayment changes that shift.
Key takeaways
- Interest is calculated on your current outstanding balance each month, not a fixed amount.
- Early payments are interest-heavy; later payments are principal-heavy, because the balance shrinks over time.
- This is why prepaying earlier in a loan's life generally saves more total interest than the same prepayment made later.
- A full amortization table lets you see this month-by-month for your specific loan, with or without a prepayment.
See your own amortization schedule
View the full month-by-month breakdown for your loan, with and without a prepayment.
Frequently asked questions
Why does my EMI go mostly to interest at the start of my loan?
Interest is calculated on your outstanding balance, which is largest at the very start of the loan. As each payment reduces the balance slightly, the interest portion of the next payment shrinks and the principal portion grows - this compounds over the life of the loan, which is why the split shifts so much by the end.
Does a longer loan tenure mean I pay more total interest?
Generally yes, for the same loan amount and rate - a longer tenure means the balance (or a large portion of it) stays outstanding for more months, accruing interest for longer, even though each individual EMI is smaller.
How does the amortization schedule change if I make a prepayment?
A prepayment reduces your outstanding principal immediately, which reduces the interest portion of every subsequent payment in the schedule, and - depending on which option you choose - either shortens the schedule (fewer remaining months) or reduces the EMI for the remaining months. See our calculator's amortization table to see this month-by-month for your own loan.