Mortgage Amortization Calculator
See your full mortgage payment, total interest, and a sample amortization schedule showing how principal and interest shift over the life of the loan.
Example
For a $300,000 loan at 6.5% over 30 years (360 months): the monthly payment is $1,896.20, total interest is $382,633.47, and total paid is $682,633.47. In year 1 about $19,401 goes to interest and only $3,353 to principal; by year 20 it flips to roughly $11,263 interest vs $11,491 principal.
How it works
Enter the loan amount, annual interest rate, and term in years. The tool computes your fixed monthly payment with M = P*r/(1-(1+r)^-n) and amortizes month by month to show interest vs principal at key milestones.
Good to know
This Mortgage Amortization Calculator turns three inputs — loan amount, annual interest rate, and term in years — into your fixed monthly principal-and-interest payment, plus a breakdown of total interest, total paid, and the number of months until payoff. It is built for home buyers comparing loan offers, current owners weighing a refinance, and anyone trying to understand where their money actually goes over the life of a mortgage.
What sets it apart from a basic payment calculator is the milestone schedule: it aggregates each full 12-month period and reports interest paid, principal paid, and ending balance at year 1, year 10, year 20, and final payoff. That lets you see the amortization "flip" — early on, the bulk of every payment is interest because it is charged on a large remaining balance, and only late in the term does most of the payment go toward principal.
To read the results, start with the monthly payment figure, then look at the principal-versus-interest bars and the schedule rows. If the total interest number surprises you, that is normal: on a long-term loan the interest can rival or exceed the amount borrowed. Use the year rows to gauge how slowly the balance falls in the first decade.
One practical caveat: this figure is principal and interest only. Your actual monthly housing cost also includes property taxes, homeowners insurance, PMI if your down payment is under 20 percent, and any HOA dues, so budget those separately. A useful exercise is to nudge the rate up or down by a fraction of a percent to see how sensitive your total interest is to the rate you lock in.
Frequently asked questions
Why does so much of my early payment go to interest?
Interest is charged on the remaining balance each month, which is highest at the start. As principal shrinks, the interest portion drops and more of each fixed payment pays down the loan — the year 1 vs year 20 rows show this shift clearly.
Does this include property taxes, insurance, or PMI?
No. This calculator shows principal and interest (P&I) only. Your full monthly housing cost (PITI) would also include property taxes, homeowners insurance, PMI if applicable, and any HOA dues, which are not modeled here.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser; nothing is uploaded.
Is this financial advice?
No. These are educational estimates — consult a qualified financial professional before making decisions.
People also ask
What is a mortgage amortization schedule?
It is a table that breaks each payment into the portion going to interest and the portion going to principal, along with the remaining balance after that payment. Over time the interest share shrinks and the principal share grows, even though the total payment stays the same.
How is a fixed monthly mortgage payment calculated?
It uses the formula M = P*r/(1-(1+r)^-n), where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. This calculator applies that formula and then amortizes month by month.
How much interest do you pay on a 30-year mortgage?
It depends on the loan amount and rate, but on a long term the total interest can approach or exceed the amount borrowed. For example, a $300,000 loan at 6.5% over 30 years accrues roughly $382,633 in interest, more than the original principal.
Does making extra principal payments reduce total interest?
Yes, paying extra toward principal lowers the balance that interest is charged on, which reduces total interest and shortens the payoff time. This particular calculator models a standard fixed payment and does not include an extra-payment field.
What is the difference between P&I and PITI?
P&I is principal and interest, the loan repayment portion of your payment. PITI adds property taxes and insurance (and often PMI and HOA dues), representing your full monthly housing cost. This tool shows P&I only.
Why is my mortgage balance barely going down in the first few years?
Because interest is charged on the outstanding balance, which is largest early in the loan, most of each early payment covers interest rather than principal. The balance falls slowly at first and then accelerates as the principal portion of each payment grows.
Does a shorter loan term save money on interest?
A shorter term generally means a higher monthly payment but substantially less total interest, since you borrow the money for fewer years. You can compare this by changing the term value and watching the total interest figure update.
How does the interest rate affect total mortgage cost?
Even small rate changes can shift total interest by tens of thousands of dollars over a long term, because the rate compounds across hundreds of payments. Adjusting the rate input in small increments shows how sensitive the totals are.
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