Amortization Schedule Calculator | GrabCalc

Currency:

Loan amount

$

The starting amount you borrowed or owe.

Interest rate

%

Fixed annual interest rate on the loan.

Loan term (years)

Repayment period in whole years (1 to 40).

Extra monthly payment

$

Extra toward principal every month — shortens the schedule

Enter your loan amount, interest rate, and term above to see your monthly payment and full year-by-year amortization breakdown.

How to Use This Calculator

Here is how to map out your loan's full repayment schedule in four straightforward steps:

1

Start with what you owe

Punch in the loan amount, your annual interest rate, and enter your term in years. 30 years is standard, but you can choose anything from 1 to 40.
2

Throw in an extra principal payment

Even $50 or $100 extra each month knocks down principal faster. Leave it blank for a baseline run.
3

Check the top numbers

You'll see your required payment, lifetime interest charges, and the exact count of monthly checks.
4

Watch the interest shrink year by year

Scroll down to the table. Early years are mostly pure interest, but principal takes over as the balance drops.

The Formula

Your fixed monthly installment comes from the standard amortization equation. It balances out your principal and compound interest so your loan zeroes out on the final month:

M = P × [ r(1 + r)ⁿ ] ÷ [ (1 + r)ⁿ − 1 ] When r = 0%: M = P ÷ n

Once that monthly installment is set, your lender runs a monthly loop to determine where your money goes:

Each Month: Interest Paid = Balance × (Annual Rate ÷ 12) Principal Paid = Monthly Payment + Extra − Interest Paid New Balance = Balance − Principal Paid

Here's what each part means when you look at your loan paperwork:

P The starting principal or initial loan balance you borrowed.
r Monthly interest rate (annual rate divided by 12, then divided by 100; 6% annual becomes 0.005 each month).
n Total count of monthly installments across your loan term (30 years equals 360 payments).
M Fixed base monthly installment covering principal and interest, before taxes or insurance.
Extra Additional cash applied directly to principal each month.

Why early payments feel like running in place: Interest is calculated on your remaining balance. In year one, you owe nearly the full balance, so interest eats most of your check. As payments chip the balance down, less interest accrues, leaving more of your fixed payment to attack the debt.

Example

Let's run a realistic scenario: you borrow $300,000 at a 6.0% fixed rate over 30 years with zero extra payments. Oh, 100%. Seeing a relative pay EMIs for an entire year only to have the principal drop by what felt like loose change was wild. Makes total sense once you realize the bank takes their cut first, but it's still frustrating to see.

Starting Loan Amount: $300,000.00

Annual Interest Rate: 6.0%

Repayment Term: 30 years (360 months)

Base Monthly Payment: $1,798.65

Month 1 Interest Charge: $300,000 × 0.005 = $1,500.00

Month 1 Principal Paid: $1,798.65 − $1,500.00 = $298.65

In that first month, $1,500.00 of your $1,798.65 payment goes straight to interest. Only $298.65 chips away at principal, leaving a $299,701.35 balance. Adding up the first 12 months makes the early tilt clear:

Year 1 Totals: You send $21,583.80 in payments. Of that, $17,900.27 (83%) is pure interest. Just $3,683.53 goes toward principal, leaving a year-end balance of $296,316.47.
Year 5 Totals: After five years of checks, your remaining balance sits at $279,163.29.
The Turnaround: By year 20, the balance has shrunk enough that principal finally overtakes interest in each payment.
30-Year Total: Over the full term, you pay $347,514.57 in total interest on that $300,000 loan, bringing total payments to $647,514.57.

Adding $100 extra per month toward principal from day one pays off the loan in 313 months (26 years, 1 month) and drops total interest to $294,168.10 — saving over $53,000 and cutting nearly four years off your debt.

Frequently Asked Questions

What is loan amortization?

Amortization is the process of paying off debt in regular installments where the split shifts over time. Each check covers that month's interest charge first, and whatever is left reduces your principal balance.

Why is my early payment mostly interest?

Interest gets calculated against your remaining balance, which is largest at the start. Because you owe so much early on, interest eats most of your check until years of payments knock the balance down.

How do extra payments change the schedule?

Extra payments skip interest entirely and subtract directly from principal. That immediately reduces next month's interest charge, accelerating your amortization table and saving thousands over the loan term.

How is this different from the mortgage calculator?

A mortgage calculator focuses on your overall monthly budget, adding property taxes and insurance. This schedule shows where every dollar goes over time. A home loan, without question. It's way too much money to take on without knowing where every single rupee is actually going. A car can wait — I'd rather have my head wrapped around a mortgage first. Most banking portals make this breakdown hard to find, which is why I built this page.

Does the schedule change if I refinance or make a lump-sum payment?

Yes. Any change to your interest rate, balance, or term creates a new schedule. If you refinance or drop a lump sum into your loan, re-run your numbers with the updated balance to see your revised timeline.