Amortization Calculator
View a full loan amortization schedule with optional extra payments.
Payment plan summary
See the cost and payoff impact of extra payments
Compare the base plan with an accelerated payoff by adding an extra monthly payment above.
Base plan
$1,896.20 / month
- Payoff
- Month 360
- Total interest
- $382,633.47
- Total paid
- $682,633.47
Selected plan
$1,896.20 / month
- Payoff
- Month 360 of 360
- Total interest
- $382,633.47
- Total paid
- $682,633.47
Interest saved
No reduction
Compared with the base plan
Final payment
$1,896.20
Due in month 360
Time saved
None
Calendar date needs a start date
Estimate only: this models a fixed annual rate with monthly payments and assumes extra payments reduce principal. It covers principal and interest, not taxes, insurance, fees, or prepayment penalties. Monthly values use full-precision math and the final payment is adjusted to clear the remaining balance; lender statements may differ when payments are rounded or applied differently.
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $1,896.20 | $271.20 | $1,625.00 | $299,728.80 |
| 2 | $1,896.20 | $272.67 | $1,623.53 | $299,456.12 |
| 3 | $1,896.20 | $274.15 | $1,622.05 | $299,181.97 |
| 4 | $1,896.20 | $275.64 | $1,620.57 | $298,906.34 |
| 5 | $1,896.20 | $277.13 | $1,619.08 | $298,629.21 |
| 6 | $1,896.20 | $278.63 | $1,617.57 | $298,350.58 |
| 7 | $1,896.20 | $280.14 | $1,616.07 | $298,070.44 |
| 8 | $1,896.20 | $281.66 | $1,614.55 | $297,788.79 |
| 9 | $1,896.20 | $283.18 | $1,613.02 | $297,505.60 |
| 10 | $1,896.20 | $284.72 | $1,611.49 | $297,220.89 |
| 11 | $1,896.20 | $286.26 | $1,609.95 | $296,934.63 |
| 12 | $1,896.20 | $287.81 | $1,608.40 | $296,646.82 |
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How Amortization Works
A fixed-rate amortizing loan generally has a level scheduled principal-and-interest payment, apart from an adjusted final payment. As the balance falls, the interest portion decreases and the principal portion increases. Whether interest exceeds principal in an early payment depends on the rate and term.
The schedule above calculates that split for every month using your loan amount, rate, term, and extra payment. Compare the first and final rows to see how the interest share falls as the remaining principal declines.
The Power of Extra Payments
Add an amount in the "Extra Monthly Payment" field to compare the selected plan with the base schedule. The summary reports the calculated interest and time saved for those inputs rather than relying on a generic example.
The key insight: extra payments reduce the balance faster, which means less interest accrues each month when the lender applies them to principal. Confirm how your lender handles extra payments and whether your loan has a prepayment penalty. See also our loan calculator for a simpler view of your base payment, or the CFPB guidance on extra principal payments for servicing details.
- Verified: results checked against independent formulas on every release
- Last reviewed:
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How this is calculated
The schedule uses the standard fixed-rate amortization formula, with interest charged monthly on the remaining balance.
Formulas
The monthly rate is the annual rate divided by 12.
r = rate ÷ 100 ÷ 12
The level monthly payment over n months is:
payment = P × r ÷ (1 − (1 + r)⁻ⁿ)
At 0% interest the payment is the amount divided by the number of months.
payment = P ÷ n
Each month, interest is the balance times r, and whatever is left of the payment reduces the balance.
interest = balance × r; principal = payment − interest
An extra monthly payment is applied entirely to principal, so the balance falls faster and the loan ends sooner. The final payment is capped at what is still owed.
Sources
- Consumer Financial Protection Bureau, What is amortization and how could it affect my auto loan?. Explains how each payment on an amortizing loan splits between interest and principal.
How we test this
This tool is checked against independent formulas every time the site is released, and a release does not ship if a check fails. Example from the test suite: $300,000 at 6.5% for 30 years gives $1,896 payment: $1,625 interest and $271 principal in month 1. The test works out the payment independently, by bisection on the ending balance, and checks the calculator agrees.
The test is “amortization: the first payment of $300,000 at 6.5% over 30 years is $1,896 split $1,625 / $271” in tests/golden-calculators.test.mjs. More on how all tools are tested: our testing approach.
Assumptions and limits
- Fixed rate, equal monthly payments, interest compounding monthly. Adjustable-rate and interest-only loans are not modeled.
- Principal and interest only: no taxes, insurance, fees or prepayment penalties.
- Lenders may round payments to the cent or apply extra payments differently, so a statement can differ by a few dollars.
- An estimate for planning, not a loan offer or financial advice.
Last reviewed , the date of the latest change to this tool's calculation or content.
Navigation
When to use this
You just got approved for a mortgage and the lender handed you a number — $2,100 a month for 30 years. But what does that actually look like? How much of that first payment is interest vs. principal? When does the crossover happen where you're finally paying down more principal than interest? An amortization schedule answers all of this, month by month, for the entire life of your loan.
This calculator is especially powerful when you're considering extra payments. Maybe you can afford an extra $200 a month and want to see the exact impact: how many years it shaves off, how much interest it saves, and when you'd be debt-free. The side-by-side comparison of your standard schedule vs. the accelerated one makes the decision concrete rather than abstract.
Use it for any fixed-rate loan — mortgages, auto loans, student loans, or personal loans. If the interest rate and term are fixed, the amortization math applies. Variable-rate loans change the picture (and this calculator assumes a fixed rate throughout), but you can still model different rate scenarios by running the numbers at each rate.
Good to know
The formula is M = P[r(1+r)^n] / [(1+r)^n - 1]. P is the principal (loan amount), r is the monthly interest rate (annual rate / 12), and n is total number of payments (years × 12). Each month, interest = remaining balance × r, and principal = M - interest. As the balance shrinks, less goes to interest and more to principal — that's amortization.
The interest share changes with the balance. On a $300,000 fixed-rate loan at 6.5% over 30 years, the first calculated payment of about $1,896 includes about $1,625 interest and $271 principal. That example has more interest than principal early on; shorter terms or lower rates can split payments differently.
Extra payments can reduce future interest. This schedule assumes the extra amount is applied to principal each month. Actual savings depend on payment timing and how the lender credits the money. Check the CFPB's guidance on confirming principal application and review your loan for prepayment penalties.
This is a principal-and-interest estimate. The model uses a fixed annual rate divided into equal monthly periods. It does not include taxes, insurance, fees, variable rates, or lender-specific rounding. A mortgage's total monthly payment may be higher; the CFPB explains what else may be included.
Compare the remaining cost before refinancing. A new loan can change both the rate and the payoff term. Extending the term may lower the monthly payment while increasing the total interest paid. Compare the remaining payments and costs of both offers rather than assuming a lower payment means a cheaper loan.
What the comparison shows
| Result | How to use it |
|---|---|
| Base monthly payment | The scheduled principal-and-interest payment without an extra amount. |
| Selected monthly payment | The base payment plus the extra monthly principal you entered. |
| Interest saved | The difference between total base-plan interest and selected-plan interest. |
| Time saved | The number of scheduled monthly payments removed by the extra amount. |
| Final payment | The adjusted last payment needed to clear the remaining calculated balance. |
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