Example 1
- Principal: 300,000
- Rate 6.5%, term 25 years
- Extra each month: 300
6 yr 5 mo. earlier
Interest β91,174.74
An extra 300 a month shortens a 25-year loan by more than 6 years and lowers interest by about 30%.
Amortization calculator
Enter the loan amount, the annual interest rate, and the term in years. The calculator builds the payment table and shows what an extra payment changes. At 300,000, 6.5%, and 25 years, an extra 300 a month finishes 6 years and 5 months sooner, and interest falls by 91,174.74.
The three fields at the top are enough. Extra each month is under those three fields. First payment date, Extra once a year, One-time lump sum, and Payment frequency are in the options. The result is an estimate and does not replace your loan contract.
Result
Enter the loan amount, the interest rate, and the term in years, then click Calculate. The drawing below is an example, not your result.
At 300,000, 6.5%, and 25 years, an extra 300 a month shortens the loan to 18 years and 7 months. In the first payment, 1,625.00 is interest and 400.62 goes to principal.
Payment schedule
How results are calculated
Principal300,000
Rate6.5%
Extra300
Time saved6 years 5 months
Interestβ91,174.74
The calculator builds a schedule of equal monthly payments, also called annuity payments, from the loan principal, the annual interest rate, and the term in years. At 300,000, 6.5%, and 25 years, an extra 300 each month means you finish 6 years and 5 months sooner, and interest falls by 91,174.74 compared with the same loan and no extra. For a loan of 400,000 at 7% for 30 years, with a first payment date of January 1, 2026, and an extra 6,000 once a year in December, the loan ends 10 years and 6 months sooner and interest falls by 222,094.77.
A one-time lump of 15,000 on payment 24, on 200,000 at 5.5% for 20 years, shortens the loan by 2 years and 3 months and lowers interest by 22,880.72. The extra goes to principal. The calculator uses a fixed rate: it does not change the rate during the term, and it does not add a prepayment fee. This table is only an illustration, not the schedule from a bank offer.
Required fields are Loan principal, Annual interest rate (%), and Loan term (years). Extra each month is under those three fields. The options include First payment date, Extra once a year, Month for the yearly extra, One-time lump sum, Lump sum on payment #, and Payment frequency. The calculator fills the date column from First payment date. If that field is empty, it uses the first day of the current month. You can compare the loan with an extra to the same loan with no extra. A short comparison, without the full table, is in the loan overpayment calculator.
The page for the balance after payments already made shows one amount, not a table. Debt repayment estimates how long a balance takes to pay off with a fixed payment. The loan installment page shows only the payment of 1,112.22, without a chart. This page shows the full table. The currency in the header only labels the amounts. It does not convert the loan. In the rate field, 6.5 and 6,5 are the same rate.
The calculation needs a loan principal greater than zero and a term greater than zero. The annual interest rate may be zero. A negative rate is an error. This is a fixed-rate calculation, not a credit decision and not a change to the contract. An offer may round each payment differently and may add a fee that this page does not include.
Type a principal of 300,000, a rate of 6.5, a term of 25 years, and an extra of 300, click Calculate, and check 6 years and 5 months and 91,174.74. Then try 200,000 at 5.5% for 20 years, with a 15,000 lump on payment 24, to see 2 years and 3 months and 22,880.72. The payment set in the contract stays the same every month. An extra payment does not reduce it.
How to use
- Enter the loan principal, for example 300,000, the annual interest rate, for example 6.5, and the term in years, for example 25.
- Type the extra each month under those fields. Click 100, 250, or 500, and the calculator puts that amount in the field.
- In the options you can set the first payment date, an extra once a year and its month, a one-time lump sum with the payment number, and how often you pay.
- Click Calculate. At 300,000, 6.5%, 25 years, and an extra 300 a month, the loan ends 6 years and 5 months sooner and interest falls by 91,174.74.
- A short comparison, without the table, is in the loan overpayment calculator. The loan balance page shows the balance after the payments you choose.
Annuity schedule and extras in this table
The calculator builds a full table of equal payments and also shows the same loan with an extra payment. At 300,000, 6.5%, and 25 years, an extra 300 a month means you finish 6 years and 5 months sooner, and interest falls by 91,174.74.
- annuity
- An annuity payment is the same amount each month. Part of it is interest, and part of it pays down the principal. At 300,000, 6.5%, and 25 years, interest saved is 91,174.74 compared with the same loan and no extra.
- extras
- These are payments above the scheduled installment. They reduce the balance faster. An extra 300 a month lowers interest by 91,174.74 and shortens the loan by 6 years and 5 months.
- Interest saved
- This is the interest on the loan with no extra, minus the interest on the loan with an extra. The first example saves 91,174.74. A yearly 6,000 in December on 400,000 at 7% for 30 years saves 222,094.77.
Examples
Example 2
- Principal: 400,000
- Rate 7%, term 30 years
- First payment date: Jan 1, 2026
- Extra once a year: 6,000 in December
10 yr 6 mo. earlier
Interest β222,094.77
An extra 6,000 each December, with the first payment in January, shortens a 30-year loan by more than 10 years.
Example 3
- Principal: 200,000
- Rate 5.5%, term 20 years
- Lump sum: 15,000 on payment #24
2 yr 3 mo. earlier
Interest β22,880.72
A lump sum two years into the loan immediately lowers the principal and shortens the rest of the schedule.
Example 4
- Principal: 200,000
- Rate 6%, term 20 years
- Extra each month: 200
4 years 1 mo. earlier
Interest β33,576.06
On a 20-year loan, an extra 200 each month takes a little more than four years off the schedule. Interest falls by 33,576.06.
Example 5
- Principal: 120,000
- Rate 7.5%, term 12 years
- Extra each month: 100
1 year 4 mo. earlier
Interest β7,757.25
On a 12-year loan, the same kind of extra is smaller, so the loan ends only 1 year and 4 months sooner. Interest falls by 7,757.25.
When to use this calculator, and when to use a simpler one
- Choose this schedule when you want every payment: interest, principal, and the remaining balance.
- If you only need a quick answer to βhow much do I save by overpaying?β, the loan overpayment calculator is enough.
- If you only want the balance after a chosen number of payments, the loan balance calculator is enough.
- If you have one debt and a fixed payment, and you do not need a month-by-month loan table, use Debt repayment.
Related calculators
An extra 300 a month on a 300,000 loan
At 300,000, 6.5%, and 25 years, the monthly payment is 2,025.62. In the first payment, 1,625.00 is interest and 400.62 goes to principal. About 80% of the first payment is interest.
Over the full term with no extra, interest is 307,687.31, which is more than the amount borrowed. An extra 300 a month finishes 6 years and 5 months sooner, at 18 years and 7 months. Interest falls by 91,174.74, about 30%.
Paying half the monthly amount every two weeks, with Extra each month left empty, ends the loan 4 years and 2 months sooner than the monthly schedule. Interest falls by 60,470.74. The calculator counts 26 half-payments a year.
In the United States, a prepayment penalty depends on the loan contract. This calculator does not subtract that penalty. The result is an estimate and does not replace the loan contract.
Frequently asked questions
How much does an extra 300 a month save on a 300,000 loan at 6.5% for 25 years?
The loan ends 6 years and 5 months sooner. Interest falls by 91,174.74 compared with the same loan and no extra.
What does 6,000 a year in December do on 400,000 at 7% for 30 years?
The loan ends 10 years and 6 months sooner, and interest falls by 222,094.77. The first payment date is January 1, 2026, as in the example.
What does 15,000 on payment 24 do on 200,000 at 5.5% for 20 years?
The loan is 2 years and 3 months shorter, and interest falls by 22,880.72. You type the payment number in Lump sum on payment #.
Is this the schedule from a bank offer?
No. The calculator uses a fixed rate, with no prepayment fee and no rate change during the term. This table is only an illustration, not the schedule from a contract.
How is this different from loan overpayment?
On this page you see every payment. Loan overpayment shows one comparison, without the full table. You can check the same extra of 500 on both pages.
Do I type the term in months?
The field is Loan term (years). For a 25-year loan, type 25. Do not convert the years into months. Month for the yearly extra is a separate list, from January to December.
Does the extra reduce the regular payment?
No. The extra goes to principal, on top of the payment. The payment from the contract stays the same, the balance falls faster, and the table gets shorter.
Can I type 6.5 with a comma in the rate field?
Yes. 6,5 and 6.5 are the same rate. The currency in the header only labels the result. It does not convert the loan.
Where do I see the balance after 60 payments, without the full table?
On the page Loan balance after payments made. This page shows the whole table, not one amount.
Is 91,174.74 a guarantee from an offer?
No. It is a fixed-rate calculation. An offer may round differently and may add a fee. It is not a credit decision.
Knowledge sources
The calculator uses equal payments at the rate you type. This is a calculation, not a contract with a lender.
Page updated September 30, 2026.