Amortization Calculator
Last reviewed:
Generate monthly and yearly schedules for a fixed-rate loan. Compare principal, interest, remaining balance and extra-payment payoff, including a capped final payment.
15-year example: A $300,000 loan at 6.5% has a $2,613.32 monthly principal-and-interest payment and $170,397.98 total interest over 180 payments. Enter your own rate and term below; example rates are not current offers.
Enter Your Details
The default 6.75% is an example. Enter a fixed annual rate from 0% to 30%, a balance up to $100 million and an extra payment up to $100 million. Payments are monthly; taxes, insurance, HOA, fees, rate changes and payment pauses are excluded.
Amortization Decision Support System
Worked example: $320,000 at 6.75%, 30 years, no extra payment.
How Mortgage Amortization Actually Works
DIRECT ANSWERHow the payment is split: Each month, interest equals the remaining balance times the annual rate divided by 12. The rest of the payment reduces principal. Extra principal reduces the balance used for later interest.
For the $320,000 example at 6.75% over 30 years, scheduled P&I is $2,075.51, total interest is $427,185.01 and payoff takes 360 payments.
This estimate keeps the rate fixed and assumes each extra payment is applied to principal on the monthly payment date. A servicer’s payoff quote can differ because of payment dates, rounding, charges or accrued interest.
Your First Payment: Principal and Interest
CALCULATEDInterest share · 86.7% of the first payment
First payment: $1,800.00 interest + $275.51 principal = $2,075.51. This is a payment breakdown, not a borrower percentile.
Your Repayment Summary
MODEL fincalcs.coRepayment recap: 360 payments
Loan amount: $320,000.00
Total principal and interest: $747,185.01
First payment with extra: $2,075.51
Calculated from the displayed example until you select Calculate. These are loan-schedule amounts, not national or community averages.
Where Your Payments Go Over Time
INTEREST FRONT-LOADEDWorked example: $320,000 at 6.75%, 30 years, no extra principal. Selected years below; the main schedule shows every period.
| Year | Payment | To Interest | To Principal | Remaining Balance |
|---|---|---|---|---|
| 1 | $24,906.17 | $21,495.77 | $3,410.39 | $316,589.61 |
| 5 | $24,906.17 | $20,442.05 | $4,464.12 | $300,402.27 |
| 10 | $24,906.17 | $18,655.89 | $6,250.28 | $272,963.20 |
| 15 | $24,906.17 | $16,155.06 | $8,751.10 | $234,545.34 |
| 20 | $24,906.17 | $12,653.62 | $12,252.55 | $180,755.93 |
| 25 | $24,906.17 | $7,751.19 | $17,154.98 | $105,444.56 |
| 30 | $24,906.17 | $887.22 | $24,018.94 | $0.00 |
Lifetime modeled payments: $320,000.00 principal + $427,185.01 interest = $747,185.01.
Why Amortization Is Front-Loaded
The interest amount follows the balance. At a positive fixed rate, the balance generally starts at its highest point. As monthly principal payments reduce it, the interest charged next month falls. How much goes to interest depends on the rate and term; it is not a fixed percentage for all mortgages.
The scheduled payment stays level. Principal and interest shift within that payment. Extra principal normally shortens the schedule without changing the required P&I amount in this model; the last payment is smaller when needed to settle the balance.
Zero interest is different. The payment is loan amount divided by payment count, and every dollar reduces principal. Extra payments reduce time to payoff but cannot save interest when the rate is zero.
Extra Principal Payment Impact
SENSITIVITYSame $320,000 loan, 6.75% and 30-year term. Each row replaces the extra-payment input with the listed monthly amount, starting with payment 1.
| Extra/Month | Payoff (Months) | Months Saved | Interest Saved | Total Interest |
|---|---|---|---|---|
| $0.00 | 360 | 0 | $0.00 | $427,185.01 |
| $50.00 | 335 | 25 | $36,171.33 | $391,013.68 |
| $100.00 | 314 | 46 | $65,847.61 | $361,337.40 |
| $200.00 | 280 | 80 | $112,077.71 | $315,107.29 |
| $250.00 | 266 | 94 | $130,561.69 | $296,623.31 |
| $500.00 | 214 | 146 | $196,070.20 | $231,114.81 |
| $1,000.00 | 157 | 203 | $264,617.89 | $162,567.12 |
Savings compare each scenario with the same loan and no extra principal. They exclude fees, taxes and investment alternatives. Extra payments use cash that is no longer available for other expenses.
Extra Payment Strategies Compared
STRATEGYCompare payment size, payoff time and interest for the same principal and rate. The 15-year row changes the term; it is not a refinancing quote and includes no closing costs.
| Strategy | First Payment | Payoff (Months) | Total Interest |
|---|---|---|---|
| Selected monthly extra | $2,075.51 | 360 | $427,185.01 |
| No extra payment | $2,075.51 | 360 | $427,185.01 |
| $100 extra per month | $2,175.51 | 314 | $361,337.40 |
| $500 extra per month | $2,575.51 | 214 | $231,114.81 |
| 15-year term, same rate, no extra | $2,831.71 | 180 | $189,707.85 |
Annual lump sums and exact biweekly posting are different schedules. Use the Mortgage Payoff Calculator or Biweekly Mortgage Calculator for those comparisons.
The Math Behind Amortization
TRANSPARENT1. Scheduled payment: M = P × r / [1 − (1 + r)−n], where P is principal, r is annual interest rate (%) ÷ 1,200, and n is years × 12. At 0%, M = P ÷ n.
2. Monthly interest: beginning balance × r. The $300,000, 6.5%, 15-year example starts with $1,625.00 of interest.
3. Principal: payment including extra − interest. With no extra, the first principal payment is $988.32 and the remaining balance is $299,011.68.
4. Final payment: never more than the remaining balance plus that month’s interest. Monthly rows are summed into yearly totals; arithmetic stays unrounded until display. Actual lender rounding and accrual conventions can differ.
How Amortization Connects to Your Plan
CONNECTEDPayoff acceleration interacts with refinancing, retirement savings, and debt strategy.
Should You Pay Extra Principal?
The calculator shows the loan arithmetic. These household factors help you decide whether the extra payment is affordable.
| Factor | Question | Why It Matters |
|---|---|---|
| Other debt | What are its rates and required payments? | Compare interest costs while keeping all required payments current. |
| Employer match | What match and vesting terms apply? | Check the benefits you might give up by reducing retirement contributions. |
| Cash reserves | Can you cover unexpected bills? | Extra principal is not readily spendable cash. |
| Mortgage terms | Are extra principal or recasting allowed? | Check application instructions, fees and any prepayment penalty. |
| Time horizon | How long do you expect to keep the loan? | Lifetime savings assume you keep paying until modeled payoff. |
Five Amortization Mistakes to Avoid
| Mistake | What to Check |
|---|---|
| Using a rate that is not your contract rate | The default is an example. Enter your fixed annual rate and remaining repayment assumptions. |
| Treating the P&I result as total housing cost | Add property taxes, insurance, mortgage insurance and HOA separately when budgeting. |
| Assuming extra payments lower the required payment | This model keeps scheduled P&I unchanged; a recast or refinance is a separate decision. |
| Comparing lifetime savings with a short holding period | If you sell or refinance sooner, compare costs through that date and the remaining balance. |
| Using the calculator as a payoff quote | Ask your servicer for the dated payoff amount and confirm extra-principal instructions. |
CFPB servicing guidance explains checking how payments are applied. CFPB prepayment guidance explains why your contract matters. Sources checked October 24, 2026.
What Should You Do Next?
UPDATES LIVEThree ways to use your calculated schedule.
Rate moves, refi alerts, and housing-market context every Monday.
People Also Calculated
This calculator is for informational and educational purposes only. Results are estimates based on the information you provide and standard financial formulas. This is not financial advice. Consult a qualified financial advisor for decisions specific to your situation. Full Disclaimer
Learn More About Amortization
Things to Know
Essential concepts for understanding your results
How It WorksWhat does an amortization schedule show?
An amortization schedule separates each payment into principal and interest, then shows the remaining balance. For $300,000 at 6.5% over 15 years, payment 1 is $2,613.32: $1,625.00 interest and $988.32 principal. Select Monthly for every payment or Yearly for annual totals.
Extra PaymentsHow do extra payments change the amortization schedule?
Extra principal reduces the balance used to calculate later interest. In that 15-year example, adding $100 each month pays off in 170 months instead of 180 and saves $11,549.35. The last payment is $297.19, rather than the full regular amount.
Negative AmortizationWhat is negative amortization?
Negative amortization means unpaid interest is added to the balance because the payment does not cover it. This calculator models a fully amortizing fixed-rate loan; it does not model payment-option plans, deferred payments or interest capitalization.
Refinance ImpactHow does refinancing reset amortization?
A refinance creates a new schedule from the remaining balance, new rate and new term. Compare future costs from today, including fees; interest already paid is a past cost. Extending the term can reduce monthly payments while increasing the time you remain in debt.
The Complete Guide to Loan Amortization
Use the schedule to answer three questions: what is the required monthly P&I payment, how much of each payment reduces the balance, and how do extra payments change payoff? The calculator supports fixed rates from 0% to 30% and 10-, 15-, 20-, 25- or 30-year terms.
For an existing mortgage: use a current principal balance and a term that matches the repayment period you want to model. This recomputes a level payment; it does not reconstruct past payments or guarantee the same required payment as your current loan. The next payment is assumed to be one month from now. Request your official schedule from your servicer when you need contract-specific amounts.
Worked 30-year comparison: $300,000 at 6.5% requires $1,896.20 monthly P&I, with $382,633.47 interest over 360 payments. The tables below are calculations from these stated assumptions, not market averages.
How Amortization Works: Year-by-Year Breakdown
Example: $300,000 at 6.5% for 30 years, no extra principal. Each row totals the payments made during that particular year.
| Year | Annual Payment | Interest | Principal | End Balance |
|---|---|---|---|---|
| 1 | $22,754.45 | $19,401.27 | $3,353.18 | $296,646.82 |
| 5 | $22,754.45 | $18,408.66 | $4,345.79 | $280,832.93 |
| 10 | $22,754.45 | $16,745.02 | $6,009.43 | $254,328.38 |
| 15 | $22,754.45 | $14,444.51 | $8,309.94 | $217,677.42 |
| 20 | $22,754.45 | $11,263.32 | $11,491.13 | $166,995.85 |
| 25 | $22,754.45 | $6,864.32 | $15,890.13 | $96,912.49 |
| 30 | $22,754.45 | $781.30 | $21,973.15 | $0.00 |
Year 1 interest is $19,401.27; principal paid is $3,353.18. There is no universal year when principal overtakes interest: rate, term and extra payments change that crossover.
How Extra Payments Transform Your Amortization
For the same $300,000 at 6.5% over 30 years, these additional monthly payments begin with payment 1. The scheduled P&I remains $1,896.20.
| Extra/Month | Payoff Time | Time Saved | Interest Saved | Final Payment |
|---|---|---|---|---|
| $100.00 | 312 months | 48 months | $60,994.79 | $819.21 |
| $250.00 | 262 months | 98 months | $120,336.94 | $2,137.27 |
| $500.00 | 210 months | 150 months | $179,759.08 | $2,067.73 |
The final payment is capped at what is owed. Interest savings are a reduction in borrowing costs, not a guaranteed tax-free investment return; taxes, fees, other debts and cash needs can change the household trade-off.
15-Year vs 30-Year: The Amortization Trade-Off
Illustrative rates differ in this comparison: 6.5% for 30 years and 5.75% for 15 years. Both begin with $300,000 and no extra payments; neither rate is a current offer.
| Measure | 30-Year at 6.5% | 15-Year at 5.75% |
|---|---|---|
| Monthly P&I | $1,896.20 | $2,491.23 |
| Total Interest | $382,633.47 | $148,421.45 |
| Total Principal + Interest | $682,633.47 | $448,421.45 |
The 15-year example costs $595.03 more per month and saves $234,212.02 in modeled interest. Choose a payment you can sustain alongside other obligations. For a term-only comparison, keep the same rate in both cases; the personalized comparison above does that. Use the 15 vs 30-Year Mortgage Calculator to compare separate rate assumptions.
The Biweekly Payment Strategy
Twenty-six half-payments equal thirteen monthly payments per year. Actual savings depend on when the servicer applies those payments and any fees; two half-payments are not automatically two principal reductions.
A separate monthly illustration adds $158.02 (approximately one-twelfth of $1,896.20) each month to the $300,000, 6.5%, 30-year example. It pays off in 290 months and saves $87,257.51. This is a monthly equivalent illustration, not an exact biweekly schedule. Use the Biweekly Mortgage Calculator for that comparison.
Refinancing and Your Amortization: Resetting the Clock
A refinance replaces future payments with a new loan schedule. The relevant inputs are today’s balance, the proposed rate, closing costs and new term. Interest paid in earlier years is not charged again and is not a reason by itself to reject a refinance.
Extending 20 remaining years to a new 30-year term can lower the required payment but extend repayment. Compare both loans over the same planned holding period, including balances still owed at that point. The Refinance Calculator helps compare those assumptions.
Comparing Amortization by Loan Type
| Loan Structure | Payment Behavior | Use of This Calculator |
|---|---|---|
| Fixed-rate fully amortizing | Level scheduled P&I; balance reaches zero | Supported with monthly payments and a fixed rate. |
| Adjustable rate | Payment may change when the rate resets | Run separate rate scenarios; this page does not simulate resets. |
| Interest only | Interest is paid without reducing principal during that period | Outside this fully amortizing model. |
| Balloon loan | A remaining balance becomes due at a specified date | Outside this model; the capped final payment here is ordinary payoff. |
| Daily-interest loan | Interest depends on actual dates and day count | This monthly model may differ from the servicer’s schedule. |
Terms and interest methods matter more than the product label. Use the stated assumptions to decide whether this model matches your loan.
Amortization and Home Equity: Building Wealth
Equity equals home value minus remaining secured debt. This separate illustration uses a $375,000 starting home value, the $300,000 loan at 6.5% over 30 years, and hypothetical 3% annual home-value growth. Appreciation is not guaranteed.
| Year | Loan Balance | Hypothetical Home Value | Equity | Equity Share |
|---|---|---|---|---|
| 0 | $300,000.00 | $375,000.00 | $75,000.00 | 20.0% |
| 5 | $280,832.93 | $434,727.78 | $153,894.85 | 35.4% |
| 10 | $254,328.38 | $503,968.64 | $249,640.26 | 49.5% |
| 15 | $217,677.42 | $584,237.78 | $366,560.36 | 62.7% |
| 20 | $166,995.85 | $677,291.71 | $510,295.87 | 75.3% |
These equity amounts exclude transaction costs, maintenance, other liens and taxes. They are not an investment-return calculation. Use the Home Equity Calculator to test a different value or balance.
Payoff Strategies That Work With Amortization
Recurring extra principal: choose an amount you can sustain. For the $300,000, 6.5%, 30-year example, rounding the full modeled payment up to $2,000 means about $103.80 extra each month. The unrounded $2,000-payment illustration pays off in 310 months and saves $62,876.81.
One-time or annual amounts: their effect depends on exactly when they are applied. The input above models a recurring monthly amount, not a dated lump sum. Use the Mortgage Payoff Calculator for another payoff strategy.
Recasting: ask the servicer whether your loan can be re-amortized after a principal reduction and what conditions or fees apply. A recast can change the required payment; extra principal alone leaves scheduled P&I unchanged in this model.
The Amortization Formula
For positive monthly rate r, the level payment is M = P × r / [1 − (1 + r)−n]. P is principal, r is the annual interest rate (%) ÷ 1,200, and n is the total number of monthly payments. For zero interest, M = P ÷ n.
For $300,000 at 6.5% over 15 years, r = 6.5 ÷ 1,200 and n = 180, giving $2,613.32 per month. Use the full rate in calculation; the decimal shown here is not truncated before computing the payment.
Each month: interest = opening balance × r; payment = the smaller of scheduled P&I plus extra or balance plus interest; principal = payment − interest; new balance = old balance − principal. Yearly totals sum these monthly rows.
Amortization Glossary
Amortization: repayment of principal over time through scheduled payments.
Amortization schedule: payment-by-payment interest, principal and remaining balance; the yearly view aggregates those rows.
Principal: the borrowed amount still owed, excluding future interest.
Interest: the cost of borrowing, calculated here monthly on the remaining balance.
Negative amortization: a balance increase when unpaid interest is added to principal. It is outside this model.
Balloon payment: a large remaining balance due before a loan fully amortizes. It is outside this model.
Prepayment penalty: a contractual charge that may apply to early repayment. Check your loan terms before a payoff or large principal payment.
More Amortization Questions
Interest is calculated on the remaining balance. At a positive rate, that balance is usually highest at the start. The share depends on the rate and term: for $300,000 at 6.5% over 15 years, payment 1 includes $1,625.00 interest and $988.32 principal.
Extra principal reduces modeled interest at a positive rate, but the household choice also depends on cash reserves, other debts, employer benefits, taxes and your plans for the loan. The calculator does not estimate investment returns or recommend an amount.
Choose Monthly for each payment or Yearly for the sum of payments in each year. Columns show payment, principal, interest and ending balance. A 15-year loan without extra payments has 180 monthly rows or 15 yearly rows; early payoff shortens the schedule. The final payment may be smaller.
Loan amortization repays borrowed principal. Depreciation is a decline or accounting allocation of an asset’s value. A mortgage balance and a home’s market value can change independently.
Common Amortization Mistakes
1. Confusing P&I with total housing costs. Budget separately for taxes, insurance, HOA, maintenance and any mortgage insurance.
2. Comparing different terms without stating them. A lower payment can come from a longer term even when total interest rises.
3. Assuming a payment was applied as expected. Check the servicer’s instructions and next statement when adding principal.
4. Treating lifetime savings as immediate savings. The totals assume the loan stays in place until the modeled payoff; an earlier sale or refinance changes the comparison.
5. Using an estimate as the final payoff amount. The model excludes fees and daily accrued interest. Use the servicer’s dated quote when settling the loan.
Additional Amortization Questions
In this model, principal equals that month’s payment including extra minus interest. Select the monthly schedule to see the amount for every payment. Taxes, insurance and HOA are excluded.
It is a table of loan payments showing principal, interest and the balance after each payment. This calculator offers monthly rows and yearly totals. Save Image exports the result card, not a downloadable spreadsheet of the full schedule.
It can, depending on payment amounts, posting dates and fees. Twenty-six half-payments total thirteen monthly payments each year. The extra-payment input here uses monthly posting; it does not simulate exact biweekly dates.
Find the first monthly row where principal exceeds interest. The crossover varies with rate, term and extra payments. Home equity also depends on market value and any other secured debt, which are not inputs to the repayment calculation.
A lower balance reduces future modeled interest, and full payoff ends loan payments. Other housing expenses can continue. Check your contract for charges and request a dated payoff quote from the servicer; this estimate is not that quote.
Use the current principal balance and a supported term to model a new level-payment schedule from today. There is no historical start-date input. If the remaining term or contract payment differs, request the official schedule from your servicer or use a payoff tool with those inputs.
Negative amortization occurs when unpaid interest is added to principal so the balance grows. This calculator assumes a fully amortizing fixed-rate loan and does not model payment deferrals, interest capitalization or income-driven repayment.
A principal lump sum reduces the balance used for later interest, but its impact depends on timing and payment rules. The input here represents recurring monthly extra principal. Use a payoff tool that accepts the amount and date of a lump sum for that scenario.
For $300,000 at 6.5% over 15 years, scheduled P&I is $2,613.32. Adding $100 each month pays off in 170 payments instead of 180, saves $11,549.35 in interest and leaves a final payment of $297.19. The model uses unrounded payments internally.
At 0%, scheduled payment equals loan amount divided by the number of months. Extra principal can shorten repayment but saves no interest. A zero balance has zero payments and zero interest; a blank input is not treated as zero.
Financial Pulse updates
Ask to receive Financial Pulse updates by email.
Opens an email draft for you to review and send.
You can also email hello@fincalcs.co to request updates.