Mortgage Amortization Calculator
See your full year-by-year principal vs. interest breakdown, and the exact year your payments flip from mostly interest to mostly principal.
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$2,076/mo
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Yearly schedule
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Last updated: August 17, 2026 · Reviewed by the DoCalc team
What Is a Mortgage Amortization Schedule?
An amortization schedule is the month-by-month (or year-by-year) breakdown of exactly how a fixed-rate mortgage payment splits between principal and interest over the life of the loan. The payment itself never changes on a fixed-rate loan, but the mix behind it does — early payments are mostly interest, and the split gradually flips toward principal as the balance shrinks.
Understanding this schedule matters for two practical reasons: it shows you how slowly equity actually builds in the early years of a mortgage, and it reveals exactly why extra payments made early in the loan save far more interest than the same extra payment made near payoff.
The Formula
Each month, interest is charged on whatever balance remains, and whatever's left of the fixed payment reduces principal. Because the balance shrinks every month, the interest charge shrinks too — which means more of next month's fixed payment can go to principal. This compounding effect is why the principal/interest split accelerates in the loan's back half rather than shifting at a constant rate.
Worked Example
A $400,000 home, 20% down, financed at 6.75% over 30 years produces a $2,076/mo principal & interest payment. In month 1, about $1,800 of that goes to interest and only about $276 to principal — an 87/13 split. By year 21, the annual split flips to majority-principal. By year 30, virtually the entire payment reduces the balance.
Why This Matters for Extra Payments
Because early payments are interest-heavy, an extra principal payment made in year 2 eliminates interest that would otherwise compound for 28 more years. The same extra payment made in year 25 only eliminates a few years of remaining interest. This is the single biggest reason financial advisors consistently recommend making extra payments as early as possible, rather than waiting until income rises later in life.
Pros and Cons of Reviewing Your Full Schedule
Pros: it shows your real equity-building timeline rather than just a monthly payment number, and it makes the payoff impact of extra payments concrete instead of abstract.
Cons: a full schedule can look discouraging in year 1-5, when the vast majority of the payment is still interest — it's worth remembering that home price appreciation (separate from loan paydown) is usually building equity in parallel.
Who Should Use This Calculator
Use it if you're deciding between loan terms, evaluating whether extra payments are worth it, or just want to understand where your money actually goes each year. Skip it if you have an adjustable-rate mortgage — this models fixed-rate amortization only, since ARM schedules depend on future rate resets that can't be predicted.
Frequently Asked Questions
Why does most of my early mortgage payment go to interest?
Interest is charged on the outstanding balance, which is largest at the start of the loan. As the balance shrinks with each payment, less interest accrues and more of the fixed payment goes to principal instead.
At what point do I pay more principal than interest?
It depends on your rate and term, but for a typical 30-year loan around 6-7%, the crossover lands roughly two-thirds of the way through the term. This calculator shows the exact year for your numbers.
Does a 15-year mortgage amortize differently than a 30-year?
Yes — a 15-year loan's higher monthly payment reduces principal much faster in absolute terms, so the principal/interest split reaches 50/50 far earlier than on a 30-year loan at the same rate.
How do extra payments change the amortization schedule?
Any extra amount applied to principal reduces the balance immediately, which lowers every future month's interest charge and effectively skips ahead in the schedule — shortening the loan and cutting total interest.
Is this the same as my lender's official amortization schedule?
The math is identical to what lenders use, but this is an estimate for planning — your actual schedule may include small rounding differences and reflects your real closing date, not today's date.
Does this include property tax and insurance?
No — this shows principal and interest only, which is what actually amortizes. Taxes, insurance, PMI, and HOA are separate costs that don't reduce your loan balance; see the Mortgage Calculator for the full monthly payment including those.