Amortization Calculator
This amortization calculator shows how each mortgage payment splits between principal and interest. It also totals the interest you pay over the life of the loan.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
Lifetime Cost Breakdown
Early payments are mostly interest; the principal share grows every month. Estimate only — excludes taxes, insurance, and any extra payments.
Amortization is the schedule that pays your loan down to zero over its term. Every payment is the same dollar amount, but the split between interest and principal shifts over time.
In the early years most of your payment covers interest. As the balance falls, more of each payment chips away at principal — which is why extra payments made early save the most.
These figures are estimates. For neutral, official guidance on mortgage costs and what lenders can charge, see the CFPB's Owning a Home guide.
How to Use This Calculator
- 1
Enter your loan amount: the financed balance, not the home price.
- 2
Set an illustrative interest rate and your loan term.
- 3
Review the monthly payment and how the first year splits between principal and interest.
- 4
Check the total interest figure to understand the true long-term cost of the loan.
The Formula & Assumptions
Each month:
interest = balance × monthly rate
principal = payment − interest
balance = balance − principal
Repeat until balance reaches zero.
The fixed monthly payment is computed from the standard amortizing-loan formula, then each month the interest portion is calculated on the remaining balance and the rest reduces principal.
Because interest is charged on a shrinking balance, the principal portion grows a little every month while the interest portion falls. This is why a 30-year loan front-loads interest so heavily.
Adding extra principal early in the schedule removes future interest on that amount for the remaining term, which is the single most powerful way to cut total cost.
Frequently Asked Questions
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is largest at the start. As you pay the balance down, the interest charge shrinks and more of each fixed payment goes to principal.
How can I pay less interest over the life of the loan?
Choose a shorter term, secure a lower rate, or make extra principal payments — especially in the early years. A 15-year term, for example, dramatically cuts total interest versus a 30-year term.
Does the amortization schedule include taxes and insurance?
No. Amortization covers only principal and interest. Taxes, insurance, and any mortgage insurance are separate escrow items added to your monthly payment.
What happens to amortization if I refinance?
Refinancing starts a new amortization schedule. If you reset to a fresh 30-year term, you return to the interest-heavy early years, so compare total interest, not just the monthly payment.
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Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.
It builds a payment-by-payment schedule showing how each mortgage payment splits between interest and principal. You also see how your balance falls to zero over the life of the loan.
Amortization Calculator in Florida
An amortization schedule covers only principal and interest, so it looks the same in Florida as anywhere else for a given loan. What differs is your escrow: Florida property taxes and insurance are collected on top of the amortized payment, so your actual monthly total will exceed the figure on the schedule.
How the Amortization Calculator Works
The calculator computes a fixed monthly payment, then walks the loan forward month by month. Each period it charges interest on the remaining balance, applies the rest of the payment to principal, and reduces the balance — repeating until the loan is paid off.
The Amortization Formula, Explained
Interest_month = balance × (rate / 12); Principal_month = payment − Interest_month
Early in the loan the balance is large, so most of each payment is interest and little goes to principal. As the balance shrinks, the interest portion falls and the principal portion grows — which is why progress feels slow at first and accelerates later.
The fixed payment itself comes from the standard amortizing-loan formula. The schedule simply applies that payment repeatedly, recalculating the interest split against the declining balance each month.
The Complete Amortization Calculator Guide
An amortization schedule turns an abstract loan into a concrete timeline. It shows exactly how much interest you pay each year and the precise month your balance crosses key milestones, which is invaluable for planning extra payments or a future sale.
The headline insight is front-loading. On a 30-year loan you can pay tens of thousands in interest before making much dent in the balance. Seeing that on paper is what motivates many borrowers to add principal early or choose a shorter term.
Use the schedule alongside the extra-payment calculator. A single annual extra payment, applied to principal, shifts every later row of the schedule forward and can shave years off the term — the amortization view makes that effect visible.
Amortization Calculator FAQ
Why is so much of my early payment interest?
Interest is charged on the outstanding balance, which is highest at the start. As you pay the balance down, the interest portion of each payment shrinks and more goes to principal.
How do extra payments change the schedule?
Any amount above the scheduled payment goes straight to principal, lowering the balance immediately. That reduces all future interest and pulls your payoff date earlier without changing your required monthly payment.