What amortization actually means
Amortization is the schedule a lender uses to turn one large debt into a fixed run of equal payments. Each payment covers the interest that accrued since the last one, and whatever is left over reduces the balance. Because interest is charged on the balance, and the balance falls every month, the split inside that fixed payment shifts steadily: interest shrinks, principal grows.
The consequence surprises most first-time buyers. On a 30-year loan at current rates, the first payment is roughly six parts interest to one part principal. You do not cross the halfway mark, where more of the payment goes to principal than interest, until somewhere around year twenty. This is why equity feels glacial at the start and then accelerates, and it is the single most useful thing a schedule shows you.
How this calculator works
The monthly principal and interest payment comes from the standard annuity formula, where L is the amount borrowed, r is the annual rate divided by twelve, and n is the number of monthly payments:
That payment is then walked forward one month at a time, which is what produces the schedule rather than just a total:
Principal this month = payment − interest this month
New balance = balance − principal this month
Everything else on the page is built from that loop. Total interest is the sum of the interest column. The payoff date is the month the balance reaches zero. The annual view groups twelve payments at a time starting from your first payment month, so a loan beginning in August runs August through July rather than following the calendar year.
Ownership costs are handled separately, because they are not part of the loan. Property tax is taken as a percentage of the home price, while insurance, PMI, HOA dues and other costs are entered as annual dollar amounts. Each is divided by twelve for the monthly column and multiplied across the term for the total, with one exception: PMI stops early, and the calculator only counts it for the months it is actually charged.
What each field does
- Home price and down payment. The down payment is a percentage, so the loan amount is the price less that share. Putting less than 20% down is what triggers PMI.
- Loan term. Thirty years is the default in the United States, but the same loan over fifteen years costs far less in total interest while raising the monthly payment substantially. It is worth running both.
- Interest rate. The annual nominal rate, not the APR. APR folds in fees and will read slightly higher than the rate your schedule is actually built on.
- Start date. Sets the calendar on every row and determines the payoff month. It changes no dollar figure, only the dates.
- Extra monthly payment. An additional amount applied straight to principal each month. The schedule is rebuilt around it, so the payoff date moves in and the interest total drops.
- Property taxes. Entered as a percentage of the home price per year, which is how county rates are usually quoted. A little over 1% is typical nationally, though the range across states is wide.
- Home insurance, HOA and other costs. Annual dollar amounts. Other costs is the place for maintenance, utilities or anything else you want reflected in the true monthly figure.
- PMI insurance. An annual dollar amount charged while your down payment is under 20% of the price.
Reading your schedule
The annual tab answers the questions people usually have: how much of this year went to interest, and where will the balance be when I might want to sell or refinance. The monthly tab is the one to open when you need a specific figure, such as the balance in a particular month for a payoff quote, or the interest paid in a calendar year for a tax return.
Two patterns are worth looking for. First, compare the interest column in year one against year twenty; the gap is the real cost of borrowing over a long term. Second, watch the ending balance against what you have paid in. Five years into a 30-year loan you will typically have paid a large sum and reduced the balance by less than a tenth of it. Neither figure is an error, and seeing both together is usually what prompts people to look at extra payments.
What extra payments really save
An extra payment goes entirely to principal, which permanently lowers the balance every future interest charge is calculated against. That is why the saving is so much larger than the amount paid. Add a modest sum each month to a 30-year loan and you can typically remove several years from the term and tens of thousands from the interest total, because you are cancelling compounding rather than just prepaying.
Timing matters more than size. A dollar added in year two removes nearly thirty years of interest on that dollar; the same dollar in year twenty-five removes only a few. If you can only do it for a while, do it early. Three practical cautions: confirm with your servicer that additional money is applied to principal rather than held toward your next payment, check the note for any prepayment penalty, and remember that extra payments reduce the term without reducing the required monthly payment, so they are not a substitute for an emergency fund.
PMI and the month it disappears
Private mortgage insurance protects the lender, not you, and is normally required when the down payment is under 20%. It is not permanent. Under the Homeowners Protection Act a lender must cancel it automatically once the balance reaches 78% of the original value on the original schedule, and you can request cancellation at 80%. This calculator uses the 80% point, which is the figure most lenders and comparable tools apply, and reports it as a date and a payment count so you can see how long you are actually paying for it.
Two things the schedule cannot see. Extra payments reach 80% sooner in reality, but automatic cancellation is based on the original schedule, so you generally have to ask, and a lender may require an appraisal. And on most FHA loans the equivalent charge lasts the life of the loan rather than dropping off at all, so an FHA borrower should not rely on the cancellation date shown here.
What this calculator does not cover
This is a fixed-rate model. It does not handle adjustable rates, interest-only periods, balloon payments, biweekly schedules, points, closing costs, lump-sum prepayments, recasting or refinancing. It assumes every payment arrives on time and in full, that the rate never changes, and that tax, insurance and HOA amounts stay flat for the whole term, which they will not: property assessments and premiums generally rise, so the later years of the total column are conservative.
Escrow is modelled as a simple monthly share of the annual cost. A real servicer collects a cushion and adjusts the amount each year after an escrow analysis, so your statement will differ. The total out-of-pocket figure also excludes the down payment itself, since that is paid at closing rather than over the term.
Frequently asked questions
What is a mortgage amortization schedule?
It is a table listing every payment across the life of the loan, showing how much of each one covers interest, how much reduces the balance, and what is still owed afterwards. On a fixed-rate mortgage the payment amount never changes, but the split inside it moves steadily from interest toward principal, and the schedule is the only way to see that happening.
How much of my first mortgage payment goes to interest?
Most of it. On a $320,000 loan at 6.5% over 30 years the payment is $2,022.62, of which $1,733.33 is interest and only $289.28 touches the balance. That is roughly six parts interest to one part principal. The ratio improves every month, but slowly at first.
When does more of my payment go to principal than to interest?
Later than most people expect. On that same $320,000 loan at 6.5% the crossover falls at payment 233, which is during year twenty of a thirty-year term. A lower rate moves the crossover earlier and a shorter term moves it much earlier.
How much do extra payments save on a 30-year mortgage?
Far more than the amount you add, because every extra dollar permanently removes future interest. On a $320,000 loan at 6.5%, an extra $100 a month pays it off 3 years 10 months early and saves about $61,700 in interest; $200 a month saves about $105,400 and clears it 6 years 7 months early. Starting early matters more than the size of the payment.
When does PMI come off my mortgage?
Private mortgage insurance is normally required with less than 20% down and ends as the balance falls. Under the Homeowners Protection Act your lender must cancel it automatically at 78% of the original value on the original schedule, and you may request cancellation at 80%. This calculator uses the 80% point and shows both the date and how many payments of PMI that adds up to. Most FHA loans are different: the equivalent charge usually lasts the whole term.
Does an amortization schedule include property taxes and insurance?
The loan schedule itself covers only principal and interest, since taxes and insurance are not part of the debt. They still leave your bank account each month, so this calculator shows them alongside as escrow-style costs and folds them into the total monthly figure and the total out-of-pocket column. You can switch them off to see principal and interest on their own.
Is a 15-year or a 30-year mortgage cheaper?
A 15-year term costs far less in total but demands more each month. Borrowing $320,000 at 6.5%, the 30-year payment is $2,022.62 with $408,142 of interest over the term, while the 15-year payment is $2,787.54 with $181,758 of interest. The shorter term saves roughly $226,000 in exchange for about $765 more every month.
Why does my lender's schedule differ slightly from this one?
Small gaps are normal and usually come from timing and rounding rather than a mistake. Lenders may count interest by the day rather than in equal monthly periods, your first payment may cover a longer or shorter stretch depending on the closing date, and each servicer rounds to the cent in its own way. Escrow is the larger source of difference, since a servicer collects a cushion and re-analyses your account annually. Your lender's figures are the ones that govern the loan.
This calculator produces estimates for general information only and is not financial, tax or legal advice. Your lender's figures are the ones that govern your loan, and they may differ because of rounding conventions, the exact day interest starts accruing, escrow adjustments and fees this tool does not model. Check any decision with a qualified professional. For more on how we build and verify these tools, see About CalculatorBoss and our Privacy Policy.