Mortgage Amortization Calculator

Generate a complete mortgage amortization schedule showing how every payment splits between interest and principal — and discover exactly how much total interest your loan will cost over its full lifetime.

How Mortgage Amortization Works Over Time

Amortization means spreading repayment across equal payments with a shifting internal split: Every monthly payment on a fixed-rate mortgage is identical in total amount, but what that payment accomplishes changes dramatically over time. The word "amortization" comes from the Latin "amortire" (to kill off) — each payment kills off a portion of the debt, but in the early years the debt dies very slowly because most of each payment services the interest rather than the balance. A full amortization schedule makes this invisible process visible.
Early payments are 80–90% interest — a fact that shocks most new homeowners: On a $420,000 30-year mortgage at 6.9%, month 1's $2,786 payment includes $2,415 in interest and only $371 in principal — 86.7% interest. At this rate of principal reduction, you would owe $415,500 after 12 months of payments despite having paid $33,432 total. This is why the first decade of homeownership builds equity so slowly: the bulk of every payment goes to the lender's return on capital, not to the homeowner's net worth.
The amortization crossover point — where principal finally exceeds interest — arrives late: On a 30-year mortgage at 7%, the monthly payment splits equally between interest and principal (the crossover point) at approximately month 223 — roughly 18.5 years into the loan. Before that crossover, interest consumes the majority of every payment. This means homeowners who sell or refinance before year 18 have paid mostly interest and own relatively little equity despite years of payments.
Front-loading payments with extra principal shifts the crossover dramatically earlier: Adding just $300/month in extra principal to a $380,000 loan at 7% from the first payment advances the crossover point from year 18.5 to approximately year 12 — cutting 6.5 years off the interest-heavy phase. More importantly, this shrinks the total interest paid from $531,000 to approximately $390,000 — a $141,000 reduction from $300/month in extra payments made consistently. The amortization schedule makes this compounding benefit concrete and visible.
Viewing the full schedule reveals the shocking total interest cost of homeownership: Most buyers focus on the monthly payment — but the amortization schedule reveals the full picture. A $350,000 30-year mortgage at 7% requires 360 payments of $2,329 each, totaling $838,440 paid to retire a $350,000 debt — meaning the lender receives $488,440 in pure interest, 40% more than the original loan amount. Seeing this figure in a single table motivates many buyers to pursue early payoff strategies with a clarity that no monthly payment figure alone can provide.

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How to Generate and Read Your Amortization Schedule

Enter your loan details to generate the base schedule: Input the loan amount (home price minus down payment), annual interest rate, and loan term in years. The calculator immediately generates a row for each of the 180 or 360 payments showing the interest component, principal component, and remaining balance after that payment.
Identify the interest-to-principal crossover row: Scroll through the schedule to find the first row where the principal column exceeds the interest column — this is your amortization crossover point. On a 30-year loan at typical rates, expect this to occur somewhere between years 17 and 20. Note the payment number and how much equity you will have built by that date.
Calculate total interest paid using the schedule totals: The schedule's running totals show cumulative interest paid at any point in the loan. Read the total interest column at the final row to see the complete lifetime interest cost — this is the true cost of the loan beyond the principal you borrowed.
Model an extra monthly payment to see the accelerated schedule: Enter an additional monthly principal payment (try $100, $250, or $500) and observe how the schedule shortens — specifically how many rows disappear from the end and how the total interest line in the final row decreases. The reduction in total interest is your quantified return on making extra payments.
Check your equity position at any future date: Use the schedule to find the remaining balance at a target future date — for example, your remaining balance in year 7 (relevant for refinancing decisions) or year 10 (relevant for HELOCs). Subtract the balance from your home's estimated value to calculate your projected equity at that date.

Real-World Use Case

David and Carmen bought their home 5 years ago with a $310,000 mortgage at 6.5% for 30 years. They pull up the amortization schedule and find their current remaining balance is $287,400 — despite having paid $126,000 in mortgage payments over 5 years, their balance has dropped only $22,600. The schedule shows they've paid $103,400 in pure interest and $22,600 in principal so far. Looking ahead, the schedule shows they'll cross the interest-principal crossover around month 233 (year 19.4) at their current payment. Motivated by this, they add $400/month in extra principal. The updated schedule shows the crossover now arrives at month 159 (year 13.3) and the total interest shrinks from $417,000 to $298,000 — a savings of $119,000 and 9 fewer years of payments from just $400/month in extra principal. They also confirm their year 10 equity (for a potential HELOC) will be $108,000 vs. $64,000 without the extra payments.

Best Practices for Using Amortization Data

Use the schedule to time your refinancing decisions: Refinancing is most beneficial early in the loan — when your payments are mostly interest. If you refinance in year 3, you restart the amortization clock and again pay mostly interest on the new loan. If you refinance in year 22 (when you're finally paying mostly principal), you may actually increase your total interest cost even if the new rate is lower. The amortization schedule quantifies the true cost of refinancing at any stage of your loan.
Apply year-end bonuses and tax refunds as lump-sum principal payments: A $5,000 lump-sum payment applied in year 3 of a $360,000 loan at 7% eliminates approximately $25,000 in future interest over the remaining loan life — a 5:1 interest elimination ratio. Early lump-sum payments have the highest leverage because they eliminate interest on that principal for the maximum remaining years. The amortization schedule shows precisely where a lump-sum falls and what rows it removes from the end of the schedule.
Compare bi-weekly payments against monthly using the schedule: Switching to bi-weekly payments (26 half-payments per year = 13 full payments annually) adds one extra monthly payment per year without requiring a lump sum. On a $340,000 loan at 6.75%, the schedule shows bi-weekly payments eliminate approximately 4 years and 8 months of payments and save roughly $58,000 in total interest — purely from the timing of when payments hit the balance.
Use the schedule to plan your equity milestones for strategic financial decisions: Review the amortization schedule to identify when your equity reaches 20% (PMI removal), 30% (HELOC eligibility with favorable rates), and 50% (the halfway point of your financial ownership). These milestones inform decisions about home equity lines, cash-out refinancing, and the timing of selling the property.
Examine the schedule before signing to confirm the loan terms match your expectations: If you can generate an amortization schedule from the lender's terms and it does not match the schedule they provide, there may be discrepancies in the rate, fees, or loan amount built into their calculation. Always request and verify the full amortization table from your lender before closing.

Performance & Limits

Full 360-row schedule generation: Produces a complete month-by-month amortization table for loan terms up to 30 years (360 payments), calculated instantly in the browser with no server round-trip or loading delay.
Cumulative interest tracking: Each row of the schedule shows both the interest paid in that specific month and the running total of all interest paid to date — letting you see exactly how much you've spent on interest at any point in the loan's life.
Extra payment modeling with recalculated schedule: Enter additional monthly, annual, or one-time lump-sum payments and the schedule recalculates in real time — showing the new payoff date, the removed payments at the end of the schedule, and the updated total interest figure.
Equity balance at every payment: The remaining balance column functions as an equity calculator — subtract the balance shown at any payment row from your home's current value to estimate your equity position at that future date.
Crossover point highlight: Automatically identifies and highlights the amortization crossover payment — the first month where more of your payment reduces principal than pays interest — making it easy to locate this milestone in any amortization schedule.

Common Mistakes to Avoid

Refinancing late in the loan without examining the new amortization schedule: A homeowner in year 20 of a 30-year mortgage who refinances into a new 30-year loan restarts the amortization clock — now paying mostly interest again on a smaller balance for another 30 years. Even at a lower rate, this can result in more total interest paid than simply keeping the original loan. Always compare the total remaining interest on the original loan vs. total interest on the new loan before deciding to refinance.
Assuming a 15-year mortgage means you build equity twice as fast as a 30-year: A 15-year mortgage does not simply double the pace of amortization — the higher payment and shorter term combine to make the amortization schedule dramatically front-loaded toward principal compared to a 30-year loan. On a $300,000 loan at 6.5%, a 15-year mortgage has you at 50% equity by year 8; a 30-year mortgage does not reach 50% equity until year 22. That is a 14-year difference in the equity-building rate, not simply a 2x factor.
Overlooking the difference between balance reduction and equity building: Your equity is home value minus mortgage balance — both sides of the equation move. The amortization schedule shows only the balance declining, not the home value changing. In a rising market your equity builds faster than the schedule implies; in a declining market your balance may exceed the home's value (negative equity) even while the amortization schedule shows a steadily declining balance.
Making extra principal payments without specifying "apply to principal": If you send an extra check or make an extra online payment without clearly designating it as a principal prepayment, some servicers will apply it as an advance payment on next month's regular payment — which includes interest — rather than a pure principal reduction. Always label additional payments explicitly as "principal only" and verify they were applied correctly on your next statement.

Privacy & Security

Amortization computed entirely client-side: Your loan amount, rate, term, and extra payment amounts are used only in your browser to generate the schedule — no data is transmitted, logged, or processed on any external server.
Schedule data never stored or cached: The generated amortization table, including all 360 rows of payment data, exists only in your browser's active memory and disappears entirely when you navigate away or close the tab.
No tracking of financial scenarios: Each amortization scenario you model — different rates, extra payments, different terms — is computed locally and is not tracked, analyzed, or reported to any third party.
Fully accessible without an account: Generate, view, and compare unlimited amortization schedules without providing any personal information, email address, or creating any kind of user profile.

Frequently Asked Questions

How much of a $400,000 mortgage payment is interest in the first year?

On a $400,000 30-year mortgage at 7%, your monthly payment is $2,661. In month 1, approximately $2,333 of that payment is interest (400,000 × 0.07 ÷ 12) and only $328 reduces the loan balance. Over the full first year, you'll pay $31,932 in total — but approximately $27,900 of that is interest and only $4,032 reduces your principal balance. After 12 full payments, your remaining balance is approximately $395,968 — a balance reduction of just $4,032 despite spending nearly $32,000. This first-year interest-to-principal ratio of roughly 87:13 is a fundamental characteristic of long-term amortized loans and is why the early years of a mortgage feel financially inefficient from an equity-building perspective.

What is the amortization crossover point and why does it matter?

The amortization crossover point is the specific payment number where the principal component of a monthly payment first exceeds the interest component — the moment when more of your payment goes toward owning the home than toward paying the lender. On a 30-year mortgage at 7%, this crossover occurs at approximately month 222 (year 18.5). Before this point, you are paying primarily for the privilege of having the loan; after this point, you are primarily building equity. The crossover matters because it marks the inflection point in the wealth-building nature of homeownership — strategies like making extra principal payments are specifically designed to bring this crossover point earlier in the loan timeline.

How much interest does making bi-weekly mortgage payments save?

Bi-weekly mortgage payments (paying half your monthly payment every two weeks) result in 26 half-payments per year, equivalent to 13 full monthly payments instead of 12. That one extra annual payment directly reduces principal, shortening the amortization schedule. On a $360,000 30-year mortgage at 6.875%, the standard monthly payment is $2,365 and total interest over 30 years is $491,400. Switching to bi-weekly payments ($1,182.50 every two weeks) reduces the loan term to approximately 25 years and 4 months, cutting total interest to approximately $393,000 — a savings of $98,400 with no lump sum required and no meaningful change to monthly cash flow, since most households spend money in roughly bi-weekly intervals anyway.

At what point in a 30-year mortgage have you paid half the total interest?

Due to front-loading, half the total lifetime interest on a 30-year mortgage is typically paid by year 10–13 — well before the midpoint of the loan in calendar terms. On a $350,000 loan at 7%, total lifetime interest is approximately $488,000. The cumulative interest column of the amortization schedule shows approximately $244,000 in interest has been paid by month 130 (year 10.8). This counterintuitive reality means that borrowers who sell, refinance, or pay off their loan in years 10–15 have already paid more than half of all the interest the loan would ever charge — making the first decade of homeownership the most interest-intensive period, and confirming why early extra payments carry such disproportionate long-term benefit.