Loan Amortization Calculator with Extra Payments Schedule
Calculate your monthly loan payment, interest vs principal breakdown, and interest saved with extra payments.
Loan Amortization Calculator
Fixed-rate loan with any term, optional extra payments, and a full month-by-month schedule.
Total term: 60 months (5 yrs). Any length works, for example 18 months or 7 years 3 months.
Used for the payoff date and schedule labels.
Assumes a fixed rate, monthly payments, interest on the remaining balance each month, and that extra money is applied to principal. Real loans may differ by a few cents or dollars (day-count methods, fees, payment timing). This is an estimate, so confirm with your lender.
| Year | Paid | Principal | Interest | End Balance |
|---|---|---|---|---|
| Year 1 | $6,011.40 | $4,281.59 | $1,729.81 | $20,718.41 |
| Year 2 | $6,011.40 | $4,613.97 | $1,397.43 | $16,104.44 |
| Year 3 | $6,011.40 | $4,972.18 | $1,039.22 | $11,132.26 |
| Year 4 | $6,011.40 | $5,358.16 | $653.24 | $5,774.10 |
| Year 5 | $6,011.36 | $5,774.10 | $237.26 | $0.00 |
What this tool does and who it is for
Enter a loan amount, an APR and a term in years and months, and this calculator works out the fixed monthly payment, the total interest, and the date the last payment lands. Below the results is a full month-by-month schedule showing how each payment splits between principal and interest.
You can add an extra amount every month, plus a one-time extra payment at any payment number, and see how much interest you save and how many months come off the loan. The schedule updates to match, and you can download it as a CSV file for a spreadsheet.
It works for any fixed-rate installment loan: auto, personal, student or a home loan's principal and interest. It does not add taxes, insurance or PMI, so for a full housing payment use the mortgage calculator.
Official Formula / Technical Standard
Real-World Worked Scenario
A $30,000 personal loan at 7.5% interest over 5 years (60 months) has a baseline monthly payment of $601.14 and total interest of $6,068. Adding an extra $100/month reduces the repayment term by 11 months and saves $1,152 in total interest.
When people use it
Seeing where each payment goes
Open the monthly schedule and compare the interest column in month 1 with the interest in the last year. It shows why early payments barely dent the balance on a long loan.
Testing an extra payment
Add $100 a month or a one-time $2,000 payment and compare the payoff date and total interest with and without it.
Checking a lender's quote
Enter the amount, rate and term from an offer and see whether the payment and total interest match. If not, ask about fees or a different compounding method.
Modeling an odd term
Try 42 months on a car loan or 7 years and 3 months on a personal loan. The term is not limited to 15 or 30 years.
Notes for US users
- Most US consumer installment loans calculate interest monthly on the remaining balance, which is what this tool does. Some auto and personal loans use daily simple interest, so the lender's numbers can differ slightly.
- Extra payments only reduce interest if the servicer applies them to principal. Ask how to mark a payment as principal-only, and confirm there is no prepayment penalty in your loan documents.
- In the early years of a long loan most of each payment goes to interest. That is normal amortization, not a lender trick.
Limits and what to double-check
- •Assumes a fixed rate and equal monthly payments. Adjustable-rate loans, interest-only periods, balloon payments and skipped payments are not modeled.
- •Fees, escrow, taxes, insurance and PMI are not included.
- •The payment is rounded to the cent and the last payment absorbs the rounding difference, so your lender's final payment may differ by a few dollars.
- •Extra payments are assumed to start in the first payment month and to be applied entirely to principal.
Expert Best Practices & Common Pitfalls
Recommended Best Practices
- •Specify to your lender that extra payments must be applied directly to the principal balance rather than advancing the next monthly due date.
- •Make bi-weekly payments instead of monthly payments; making 26 half-payments equals 13 full payments per year, shaving years off your loan.
- •Check for loan prepayment penalties before initiating large lump-sum principal payoffs.
Common Mistakes to Avoid
- •Failing to monitor the principal portion on monthly statements to verify extra payments were credited properly.
- •Refinancing a loan near the end of its term, which resets the amortization clock back to an interest-heavy phase.
- •Paying extra on low-interest debt while carrying high-interest credit card balances.
Features & Security Architecture
- 100% Client-Side: Zero server uploads ensure complete privacy and data confidentiality
- Fast Results: Processing happens on your own device, so there is no upload or server queue to wait for
- No Sign-Up Required: Completely free to use with no daily usage caps or account requirements
- Works on All Devices: Fully responsive across desktop, tablet, and mobile browsers
Frequently Asked Questions
What is an amortization schedule?▼
An amortization schedule is a complete table showing every scheduled loan payment over time, breaking down the exact dollar amount allocated to interest vs principal and tracking the declining loan balance.
How does an extra payment reduce total loan interest?▼
Because interest is calculated each month on the remaining principal balance, every dollar paid directly to principal permanently lowers the balance upon which all subsequent interest calculations are based.
How is the monthly payment calculated?▼
The standard formula is payment = loan x r / (1 - (1 + r)^-n), where r is the APR divided by 12 and n is the number of months. For $300,000 at 6.5 percent over 30 years that comes to $1,896.20 a month. With a 0 percent rate it is simply the loan divided by the months.
How do extra payments change the schedule?▼
Each month the interest is charged on the remaining balance, so any extra money applied to principal lowers the next month's interest. The loan finishes sooner, and the tool shows the interest saved and months saved against the same loan with no extras.
Can I download the schedule?▼
Yes. The CSV download includes the payment number, date, payment, principal, interest and remaining balance for every row, and it reflects any extra payments you entered.
Why might my lender's numbers differ slightly?▼
Lenders may use daily interest, count days differently, round at different steps, or add fees. A difference of a few dollars over the life of the loan is common. For payoff figures, ask your lender for an official payoff quote.
Does it work for a mortgage?▼
It handles the principal and interest portion. Property tax, homeowners insurance, PMI and HOA dues are not included, so use the mortgage calculator if you want the full monthly housing payment.