Amortization Calculator
Generate an amortization schedule with optional extra payments.
| # | Date | Payment | Extra | Principal | Interest | Balance |
|---|---|---|---|---|---|---|
| Run a calculation to see the schedule. | ||||||
Important Note : This calculator estimates a principal-and-interest amortization schedule only. A real total monthly mortgage payment can include taxes, homeowners insurance, and possibly mortgage insurance, so the amortization payment may not equal the borrower’s full monthly housing payment.
Use this Amortization Calculator to generate a loan repayment schedule with principal, interest, extra payments, remaining balance, total interest, total paid, payoff date, and months to payoff. Enter the loan amount, annual interest rate, loan term, and optional extra payments to see how the loan balance may decrease over time.
This calculator is useful for mortgages, personal loans, auto loans, and other fixed-rate installment loans where payments are split between principal and interest. It can also show how extra monthly payments or a one-time extra payment may reduce total interest and shorten the payoff timeline.
Reviewed by: Ajax Calculator Team
Last updated: April 30, 2026
Method source: Standard fixed-rate amortization formulas using loan amount, monthly interest rate, loan term, scheduled payment, optional monthly extra principal payment, and optional one-time extra principal payment.
Editorial standards: See our Editorial Policy for how we review and update calculator content.
What This Amortization Calculator Does
This calculator creates a month-by-month loan amortization schedule. It can estimate:
- Monthly principal and interest payment
- Total interest over the loan term
- Total amount paid
- Estimated payoff date
- Number of months to payoff
- Principal paid each month
- Interest paid each month
- Remaining loan balance after each payment
- Effect of extra monthly payments
- Effect of a one-time extra payment
The calculator focuses on principal and interest. It does not include taxes, insurance, PMI, HOA dues, escrow changes, late fees, or lender-specific charges.
What Is Amortization?
Amortization is the process of paying off a loan through scheduled payments over time. Each payment is split between interest and principal. Interest is the cost of borrowing money, while principal reduces the loan balance.
In many fixed-rate loans, the monthly principal-and-interest payment stays the same, but the split changes over time. Early payments usually include more interest because the loan balance is still high. Later payments usually include more principal because the balance has been reduced.
Amortization Calculator Formula
For a standard fixed-rate loan, the monthly payment is calculated with this formula:
M = P × [r(1 + r)n] ÷ [(1 + r)n − 1]
Where:
- M = monthly principal and interest payment
- P = loan amount or principal borrowed
- r = monthly interest rate, calculated as annual interest rate ÷ 12
- n = total number of monthly payments
After the monthly payment is calculated, each month is broken down like this:
Monthly interest = current balance × monthly interest rate
Principal paid = monthly payment − monthly interest
Ending balance = starting balance − principal paid − extra principal payment
If you enter an extra monthly payment or one-time extra payment, the calculator applies the extra amount to principal after interest is computed.
Worked Example
Suppose you have a $280,000 loan with a 6.5% annual interest rate and a 30-year term.
| Input | Example Value |
|---|---|
| Loan amount | $280,000 |
| Annual interest rate | 6.5% |
| Loan term | 30 years |
| Extra monthly payment | $200 |
| One-time extra payment | $5,000 |
| One-time extra payment month | 12 |
The estimated monthly principal-and-interest payment without extra payments is about:
$1,769.79
The monthly interest rate is:
6.5% ÷ 12 = 0.5417% per month
The first month’s interest is approximately:
$280,000 × 0.0054167 = $1,516.67
The first month’s scheduled principal is approximately:
$1,769.79 − $1,516.67 = $253.12
If a $200 extra monthly payment is added, then the first month’s total principal reduction is about:
$253.12 + $200 = $453.12
This reduces the loan balance faster and lowers future interest.
Example Amortization Schedule
| Month | Payment | Extra | Principal | Interest | Balance |
|---|---|---|---|---|---|
| 1 | $1,769.79 | $200.00 | $253.12 | $1,516.67 | $279,546.88 |
| 2 | $1,769.79 | $200.00 | $255.58 | $1,514.21 | $279,091.30 |
| 3 | $1,769.79 | $200.00 | $258.05 | $1,511.74 | $278,633.25 |
This example shows why early loan payments often reduce the balance slowly. A large part of each early payment goes toward interest because the remaining balance is still high.
Example With Extra Payments
Using the same $280,000 loan at 6.5% for 30 years, the estimated total interest without extra payments is about:
$357,124.57
If you add a $200 extra monthly payment and a $5,000 one-time extra payment in month 12, the estimated total interest may fall to about:
$240,966.66
Estimated interest saved:
$357,124.57 − $240,966.66 = $116,157.91
The estimated payoff time may drop from 360 months to about 262 months. That means the loan could be paid off about 98 months earlier, assuming the extra payments are made consistently and applied to principal.
How to Use the Amortization Calculator
- Enter the loan amount. This is the amount borrowed.
- Enter the annual interest rate.
- Enter the loan term in years.
- Select a start date to label the payment months.
- Optionally enter an extra monthly payment.
- Optionally enter a one-time extra payment.
- If using a one-time extra payment, enter the month number when it should be applied.
- Choose whether to show the first 12 payments, first 60 payments, or full schedule.
- Click Calculate to generate the monthly payment, totals, payoff date, and schedule.
How to Interpret the Results
Monthly payment (P&I) shows the regular principal-and-interest payment before optional extra payments.
Total interest shows the estimated interest paid over the life of the loan.
Total paid shows the estimated total of principal, interest, and extra principal payments included in the payoff schedule.
Payoff date estimates when the loan may be fully repaid based on the selected start date and payment assumptions.
Months to payoff shows the number of monthly payments required to reach a zero balance.
Payment is the scheduled monthly principal-and-interest payment.
Extra is the additional amount applied to principal after interest is calculated.
Principal is the part of the scheduled payment that reduces the loan balance.
Interest is the cost charged for that month based on the remaining balance.
Balance is the remaining loan amount after the payment and extra principal are applied.
How Extra Payments Affect Amortization
Extra payments can reduce the loan balance faster when they are applied to principal. Because interest is calculated on the remaining balance, reducing the balance earlier can lower future interest costs.
There are two extra payment options in this calculator:
- Extra monthly payment: an added amount paid every month toward principal.
- One-time extra payment: a single extra principal payment applied in the selected payment month.
Extra payments can shorten the payoff timeline and reduce total interest, but the actual savings depend on the loan balance, interest rate, loan term, payment timing, and lender rules.
One-Time Extra Payment Month
The one-time extra payment month tells the calculator when to apply a single extra principal payment. For example:
- Month 1 means the extra payment is applied with the first payment.
- Month 12 means the extra payment is applied after one year.
- Month 60 means the extra payment is applied after five years.
Earlier extra payments usually save more interest than later extra payments because they reduce the balance sooner.
Amortization Schedule Columns Explained
| Column | Meaning |
|---|---|
| # | The payment number in the schedule. |
| Date | The estimated payment month based on the selected start date. |
| Payment | The scheduled principal-and-interest payment. |
| Extra | Additional amount applied to principal. |
| Principal | The scheduled payment amount that reduces the balance. |
| Interest | The interest charged for that payment period. |
| Balance | The remaining loan balance after the payment. |
Loan Types This Calculator Can Estimate
This calculator can be used for many fixed-rate installment loans, including:
- Mortgage loans
- Personal loans
- Auto loans
- Student loan payoff estimates
- Business installment loans
- Debt consolidation loans
It works best when the loan has a fixed interest rate, a fixed monthly payment, and regular monthly amortization.
Mortgage Amortization vs Full Mortgage Payment
A mortgage amortization schedule usually focuses on principal and interest only. However, a real monthly mortgage payment may include additional costs such as:
- Property taxes
- Homeowners insurance
- Private mortgage insurance
- HOA or condo dues
- Escrow adjustments
If you need a total monthly housing payment estimate, use a mortgage calculator that includes taxes, insurance, PMI, and HOA dues.
Interest Rate vs APR
The interest rate is the rate used to calculate interest on the loan balance. APR, or annual percentage rate, can include the interest rate plus certain fees and loan costs.
For this amortization calculator, use the loan’s interest rate if you want a standard principal-and-interest schedule. If you enter a fee-inclusive APR instead of the note rate, the payment estimate may not match your lender’s actual amortization schedule.
Why Early Payments Are Mostly Interest
At the beginning of a loan, the balance is highest. Since monthly interest is calculated from the current balance, early payments often include a large interest portion. As the balance falls, the interest portion decreases and the principal portion increases.
This is why amortization schedules are helpful. They show how much of each payment goes toward interest and how much actually reduces the balance.
Amortization Example Table
| Loan Amount | Rate | Term | Monthly P&I | Total Interest |
|---|---|---|---|---|
| $200,000 | 6.5% | 30 years | $1,264.14 | $255,089.69 |
| $280,000 | 6.5% | 30 years | $1,769.79 | $357,124.57 |
| $300,000 | 6.5% | 30 years | $1,896.20 | $382,633.89 |
| $300,000 | 6.5% | 15 years | $2,613.32 | $170,397.67 |
These examples show principal and interest only. Taxes, insurance, PMI, HOA dues, fees, and closing costs are not included.
Common Uses for an Amortization Calculator
This calculator can help you:
- Create a monthly loan repayment schedule
- See how much interest you may pay over time
- Compare 15-year and 30-year loan terms
- Estimate how extra monthly payments affect payoff
- Estimate how a one-time extra payment affects interest
- Understand the principal and interest split in each payment
- Plan mortgage, personal loan, auto loan, or debt payoff scenarios
What This Calculator Does Not Include
This calculator does not include every possible loan cost or payment rule. It does not calculate:
- Property taxes
- Homeowners insurance
- Private mortgage insurance
- HOA dues
- Escrow changes
- Loan origination fees
- Discount points
- Late fees
- Prepayment penalties
- Variable interest rates
- Balloon payments
- Interest-only periods
For a final loan decision, review your lender’s official documents and payment schedule.
Assumptions and Limitations
- The calculator assumes a fixed interest rate.
- It assumes monthly payments.
- It assumes the same scheduled payment throughout the loan, except for final payoff adjustment.
- It assumes extra payments are applied to principal after monthly interest is computed.
- It does not include taxes, insurance, PMI, HOA dues, or escrow amounts.
- It does not model adjustable-rate loans or variable-rate loans.
- It does not include lender fees, closing costs, or APR-related charges.
- It may not match a lender’s exact schedule because of rounding, payment dates, fees, and lender-specific rules.
Tips for More Accurate Amortization Estimates
- Use the exact loan amount from your lender or loan agreement.
- Use the interest rate, not the fee-inclusive APR, for basic amortization math.
- Enter the correct loan term in years.
- Use the start date that matches your first payment month.
- Include extra payments only if you plan to make them consistently.
- Confirm that your lender applies extra payments to principal.
- Check whether your loan has a prepayment penalty.
- Use the full schedule option when you need a complete month-by-month payoff table.
Related Calculators
- Mortgage Calculator
- Mortgage Interest Calculator
- Mortgage Calculator with Taxes and Insurance
- Refinance Calculator
- Loan Calculator
- Interest Rate Calculator
References
- Consumer Financial Protection Bureau: How does paying down a mortgage work?
- Consumer Financial Protection Bureau: Principal and Interest Payment vs Total Monthly Payment
- Consumer Financial Protection Bureau: Mortgage Interest Rate vs APR
- Consumer Financial Protection Bureau: Loan Estimate Explainer
- Consumer Financial Protection Bureau: Mortgage Key Terms
Frequently Asked Questions
What does an amortization calculator do?
An amortization calculator estimates a loan payment schedule. It shows how each payment is split between principal and interest and how the loan balance changes over time.
How is a loan amortization payment calculated?
A fixed-rate amortization payment is calculated using the loan amount, monthly interest rate, and total number of monthly payments. The payment is designed to fully repay the loan by the end of the term.
What is an amortization schedule?
An amortization schedule is a table that lists each loan payment, including the payment number, date, payment amount, principal, interest, extra payment, and remaining balance.
Why does more interest appear at the beginning of the schedule?
Interest is calculated on the remaining balance. At the beginning, the balance is highest, so the interest portion is usually higher. As the balance falls, more of each payment goes toward principal.
How do extra payments affect amortization?
Extra payments reduce principal faster when they are applied to the loan balance. This can lower future interest, shorten the payoff time, and reduce total interest paid.
What does one-time extra payment month mean?
It means the payment number when the one-time extra principal payment is applied. Month 1 is the first payment month, and month 12 is after one year of payments.
Does this calculator include taxes and insurance?
No. This calculator focuses on principal and interest. It does not include property taxes, homeowners insurance, PMI, HOA dues, or escrow changes.
Should I use interest rate or APR?
Use the loan’s interest rate for a basic amortization schedule. APR can include fees and other costs, so it may not match the rate used for monthly principal-and-interest payment calculations.
Can this calculator be used for auto loans or personal loans?
Yes. It can estimate fixed-rate installment loans such as mortgages, auto loans, personal loans, and other loans with regular monthly payments.
Why might my lender’s amortization schedule be different?
Your lender’s schedule may differ because of rounding, exact payment dates, fees, escrow rules, extra payment handling, prepayment penalties, or loan-specific terms.
Disclaimer
This calculator is for educational and planning purposes only. It estimates fixed-rate loan amortization using standard principal-and-interest formulas. It does not provide financial, mortgage, legal, tax, or lending advice. Actual loan payments, interest, payoff dates, APR, fees, prepayment rules, escrow amounts, taxes, insurance, PMI, and lender terms may vary. Always review your official loan agreement, Loan Estimate, Closing Disclosure, and lender payment schedule before making borrowing or prepayment decisions.