See exactly how your mortgage payments are split between principal and interest over time.
Open Calculator →Last reviewed: March 2026
An amortization schedule is a table that shows every payment on a loan over its entire term. Each payment is split between two things: paying down the principal (the amount you borrowed) and paying interest (the cost of borrowing the money).
The schedule shows the remaining balance after each payment, how much of that payment went to interest, and how much went to principal. It's a roadmap of your debt payoff.
Amortization applies to any loan with fixed payments and a fixed term — mortgages, car loans, student loans, personal loans. If you have a 30-year mortgage, your amortization schedule will show 360 monthly payments.
I didn't understand amortization when I bought my first home. I just knew I had to pay $1,800 per month for 30 years. It wasn't until I saw the amortization schedule that I realized how much of my early payments were going to interest instead of principal.
With a fixed-rate loan, your monthly payment stays the same throughout the entire term. But the split between principal and interest changes with each payment.
In the early years, most of your payment goes to interest because the principal balance is high. As you pay down the principal, the interest portion shrinks, and more of your payment goes to principal.
Here's the formula for calculating the monthly payment on a fixed-rate loan:
M = P × [r(1+r)^n] / [(1+r)^n - 1]
Where M is the monthly payment, P is the principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of payments.
You don't need to calculate this by hand — use the amortization calculator above or any online mortgage calculator.
Let's say you take out a $300,000 mortgage at 6.5% interest for 30 years. Your monthly payment would be $1,896.
Here's what the first few payments look like:
Notice how the interest portion decreases slightly each month while the principal portion increases? That's amortization in action.
By year 15 (payment 180), the split shifts dramatically:
At the halfway point, you've paid exactly half the principal but you've paid far more than half the total interest. Over 30 years, you'll pay $382,560 in interest — more than the original loan amount.
The relationship between interest and principal is the core concept of amortization. Here's how it breaks down over the life of a 30-year mortgage:
This is why making extra payments early in the loan has such a big impact. An extra $100 toward principal in year 1 saves you far more in interest than an extra $100 in year 20.
When I looked at my own amortization schedule, I was shocked to see that after 5 years of payments, I'd only paid down $25,000 of my $300,000 principal — but I'd paid $65,000 in interest. That's when I started making extra principal payments.
Any extra payment you make toward principal reduces your balance, which reduces the interest charged in future months, which means more of your next payment goes to principal. It's a snowball effect.
Here's how extra payments affect a $300,000 mortgage at 6.5% for 30 years:
Even small extra payments add up over time. An extra $50 per month saves you over $30,000 in interest and shaves 3 years off your loan.
I started making an extra $100 payment each month in year 3 of my mortgage. Over the next 7 years, I paid down an additional $15,000 in principal and saved about $12,000 in interest. When I refinanced at year 10, I had 20% equity and was able to eliminate mortgage insurance.
Most mortgages are fully amortizing, meaning your payments are structured so that the loan is completely paid off by the end of the term. Each payment covers both interest and principal.
Some loans allow you to pay only the interest for a set period (usually 5-10 years). Your payments are lower during the interest-only period, but they increase significantly afterward when you start paying principal. These are riskier because you're not building equity during the interest-only period.
A balloon loan has low monthly payments for a set period, followed by a large "balloon" payment at the end. These are uncommon for residential mortgages but sometimes used for commercial real estate.
In rare cases, your monthly payment might be less than the interest charged, causing the principal balance to increase over time. This is called negative amortization and is a red flag — you're losing money with every payment.
An amortization schedule typically has the following columns:
Some schedules also show the cumulative interest paid and cumulative principal paid over time. These columns help you see the big picture of how your loan is being paid down.
Use the amortization calculator above to generate a full schedule for your loan. You can see exactly how much interest you'll pay over the life of the loan and how extra payments affect the payoff timeline.
The interest portion of your mortgage payment may be tax-deductible if you itemize deductions on your tax return. This is called the mortgage interest deduction.
For 2026, you can deduct interest on up to $750,000 of mortgage debt ($375,000 if married filing separately). This applies to mortgages taken out after December 15, 2017. Older mortgages may have a higher limit ($1 million).
The principal portion of your payment is not tax-deductible because it's not an expense — it's paying down your own debt.
Consult a tax professional to understand how the mortgage interest deduction applies to your situation. The deduction is only beneficial if you itemize deductions and your total itemized deductions exceed the standard deduction.
If you want to pay off your mortgage ahead of schedule, here are some proven strategies:
Instead of paying monthly, pay half your monthly payment every two weeks. Since there are 26 biweekly periods in a year, you'll make 13 full payments instead of 12. This extra payment each year can shave 4-6 years off a 30-year mortgage.
If your monthly payment is $1,896, round up to $1,900 or $2,000. The extra amount goes directly to principal and adds up over time.
Make one extra full payment each year, either as a lump sum or spread across 12 months. This alone can shave 4-5 years off a 30-year mortgage.
Use tax refunds, bonuses, or inheritance money to make extra principal payments. Even a $2,000 tax refund applied to principal can save you thousands in interest over the life of the loan.
Some lenders allow you to make a large lump-sum principal payment and then "recast" your mortgage, which recalculates your monthly payment based on the new lower balance. Your payment drops, but your loan term stays the same.
Understanding your amortization schedule is one of the most important things you can do as a homeowner. It shows you exactly how your mortgage works, how much interest you'll pay over time, and how extra payments can save you money.
The key takeaway is this: the earlier you make extra principal payments, the more interest you save. Even small amounts add up over time. And if you can refinance to a lower rate or shorter term, you can save tens of thousands of dollars.
I wish I had understood amortization before I bought my first home. It took me 5 years to realize how much of my payments were going to interest. Once I understood the math, I started making extra payments and was able to refinance into a conventional loan with 20% equity, eliminating mortgage insurance and saving hundreds per month.
Use the amortization calculator above to see your own schedule. Then decide how you want to pay it off — on schedule or ahead of time. Either way, you're building equity in your home, and that's a good thing.