How does an extra payment reduce interest?

Every extra payment reduces the principal balance before the next interest charge. Since interest is calculated on the smaller balance, the total interest owed drops. The earlier and larger the extra payment, the more interest you avoid.

How much does an extra payment shorten a loan?

It depends on the rate and term. On a 30 year, $200,000 loan at 6%, an extra $100 a month shaves over 5 years off the term. On a shorter or lower rate loan the effect is smaller, so run your own numbers.

Is paying extra every month better than a lump sum?

Both reduce principal and save interest. A consistent monthly extra payment is predictable and compounds steadily, while a lump sum removes a chunk of principal at once. Minimum payments plus consistent extra payments are generally the easiest to maintain.

When should I make an extra payment?

As early as possible. Interest accrues on a declining balance, so the savings are largest when an extra payment lands at the start of the loan. Even one extra payment early can reduce total interest and shorten the term.

Does an extra payment change my required monthly payment?

No. Your required payment stays the same; the extra is applied to principal on top of it. The bonus is that a smaller balance means your loan is cleared sooner and costs less overall.

Are there fees for paying extra on a loan?

Some lenders charge prepayment penalties, while others allow it freely. Check your loan agreement first. Mortgages and student loans typically allow extra payments without penalty, but not all loans do.

How to Use the Extra Payment Calculator

Enter your loan details and an extra monthly payment to see how much sooner you pay it off and how much interest you save.

Step-by-Step Instructions

1 Enter the loan amount, interest rate, and term.
2 Add the extra payment you plan to make each month.
3 Review the new payoff time, time saved, and interest saved.

Understanding the Inputs

Loan Amount

The total amount you borrowed, such as $200,000 on a mortgage or $18,000 on a car loan.

How to find it: Enter the full principal balance of the loan.

Why it matters: This is the balance that interest is charged against, so it anchors the entire savings estimate.

Type: number · Default: 0

Interest Rate (%)

The annual interest rate of the loan, as a percentage like 6 for 6%.

How to find it: Find the APR on your loan statement or agreement.

Why it matters: The rate determines how much of each payment goes to interest, so a higher rate means bigger savings from extra payments.

Type: number · Default: 0

Term (years)

The original loan term in years, like 30 for a mortgage or 5 for an auto loan.

How to find it: Enter the full term the loan was written for.

Why it matters: The term sets the baseline payoff and the total interest you compare your extra payments against.

Type: number · Default: 0

Extra Payment / Month

The additional amount you pay each month beyond the minimum, such as $100.

How to find it: Enter the extra you plan to pay on top of your regular payment.

Why it matters: This is the variable that shortens the loan and saves interest, so the more you enter, the bigger the effect.

Type: number · Default: 0

Tips & Best Practices

✓ A larger or earlier extra payment saves more interest.
✓ Ask your lender to apply extra payments to principal.
✓ Compare the interest saved against any prepayment penalty.

Try the Extra Payment Calculator

by CalculatorPro Tools · Updated 09-02-2026