What this Amortization Calculator does
This English-language amortization calculator produces a complete month-by-month amortization table for any fixed-rate loan — mortgage, car loan, personal loan, or auto finance. Enter a principal, an annual interest rate, and a term in years, and the tool computes your monthly payment plus a full schedule showing exactly how each payment splits between principal and interest. What surprises most first-time borrowers: in the early years of a 30-year mortgage, as much as 75–80% of each monthly payment goes to interest, barely moving the balance. The amortization chart makes that shift visible row by row, year by year. Use it as an amortization estimator before you sign, or export the complete schedule as a CSV to share with your accountant or load into a spreadsheet for further analysis. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs.
Features
- Complete amortization table. Every month of your loan term appears as its own row — payment number, principal paid, interest paid, and remaining balance. Works as a full amortization table calculator for mortgages, auto loans, or any fixed-rate installment debt.
- Yearly summary. Monthly rows are grouped by year so you can see annual totals for principal, interest, and amount paid — useful for tax-year planning and conversations with a financial planner or accountant.
- CSV schedule download. One click exports the full amortization table as
amortization-schedule.csv, ready to open in Excel or Google Sheets. The file is generated entirely in your browser with no server round-trip — a design philosophy shared by browser-native APIs like the Web Crypto API W3C Recommendation, which also perform sensitive operations entirely client-side. - Works for mortgages and auto loans. The fixed-rate amortization formula is identical for a 30-year mortgage and a 60-month car loan. Use this as a car loan payment calculator before you visit the dealership, or as a mortgage amortization estimator while you compare lender offers.
- Principal-vs-interest split at a glance. Each row shows exactly how much of your payment reduces the balance versus how much covers interest charges. This is the view that motivates extra-payment decisions — you can see precisely when the ratio crosses 50/50.
- Instant, private calculations. There is no network request. The amortization schedule recalculates the moment you change any input, and nothing is ever sent to a server. Your loan figures stay on your device, full stop.
How to use the Amortization Calculator
Fill in three fields and the full amortization schedule appears immediately. Download the CSV if you need a copy for your records or lender.
- Enter the loan amount. Type the total principal — the amount you are borrowing before interest. For a car finance loan, this is the vehicle price minus your down payment.
- Enter the annual interest rate. Use the rate from your loan offer as a percentage (e.g.,
6.5for 6.5%). This is the nominal annual rate. APR includes fees that this calculator does not model, so use the base rate for the P&I schedule. - Set the term in years. Common values are 30 or 15 for mortgages, and 3, 4, or 5 for auto loans. The calculator converts this to months internally and builds one row per month.
- Review the summary and table. The summary shows your monthly payment, total interest, and total amount paid. Scroll down for the full month-by-month amortization calendar and the collapsible yearly summary.
- Download the CSV. Click "Download CSV" to save the entire schedule. Open it in a spreadsheet to model extra-payment scenarios, or share it with a mortgage advisor or accountant.
Common use cases
- Comparing a 15-year vs 30-year mortgage. Run the same principal and rate at both terms. The 15-year monthly payment is higher, but the total interest saved is often six figures over the life of the loan. The amortization table makes that trade-off concrete before you commit.
- Auto and car loan payment planning. Enter the financed amount, the dealer or bank's annual rate, and the term (e.g., 5 for a 60-month loan) to get the exact monthly payment and total financing cost. Compare two lenders side by side by running each scenario separately — small rate differences compound significantly over a 72-month car note.
- Preparing for tax season or a financial review. Export the CSV and hand it to your accountant. The yearly summary shows exactly how much interest you paid in a given calendar year, which is relevant for mortgage interest deductions. If you also need to project investment growth over that same horizon, the [compound interest calculator](/en/compound-interest-calculator/) covers that side of the equation.
- Understanding why your balance barely moves early on. A common question from first-time buyers: after two years of payments on a 30-year mortgage, why is the remaining balance almost unchanged? The month-by-month amortization table answers it directly — you can see the interest-heavy early rows and watch the principal share grow over time.
- Evaluating a refinance. Run your remaining balance at your current rate, then run the same balance at the proposed new rate. Compare total interest remaining in both scenarios. Pair this with the [loan calculator](/en/loan-calculator/) if you need to fold in origination fees or points as part of the break-even analysis.
Frequently asked questions
Is my loan data sent to any server?
No. All calculations run in your browser using JavaScript. Nothing is uploaded, stored, or logged anywhere. Standards like NIST SP 800-63B emphasize minimizing unnecessary transmission of sensitive information — this calculator takes that principle to its logical end by never transmitting your data at all.
How is the monthly payment calculated?
The standard fixed-rate formula is M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the principal, r is the monthly rate (annual rate ÷ 12), and n is the total number of months. This assumes equal monthly payments and monthly compounding — the same model used by most U.S. mortgage lenders and auto finance companies.
Can I use this as a car loan payment calculator?
Yes. The amortization formula is identical for auto loans and mortgages. Enter the financed amount (vehicle price minus down payment), the lender's annual rate, and the term in years (e.g., 5 for 60 months). You get the monthly car payment and the full cost of financing — useful for comparing dealer financing against a bank or credit union offer.
Why does so little of my early payment go toward principal?
Interest accrues on the outstanding balance. Early in the loan, that balance is at its peak, so interest takes the largest share of each payment. As the principal falls, so does the interest portion — and the principal share grows proportionally. On a 30-year mortgage at 7%, roughly 78% of the first payment goes to interest. The month-by-month amortization table makes this ratio shift visible in a way that a single payment figure never does.
Does this calculator work for adjustable-rate (ARM) mortgages?
No — this tool models fixed-rate loans only. An ARM resets its rate periodically, and each reset requires re-amortizing the remaining balance at the new rate. After each rate change, return to this calculator, enter your current remaining balance as the new principal, and use the updated rate to get a revised schedule.
What costs are not included in this estimate?
The calculator shows only principal and interest (P&I). It does not model escrow items (property taxes, homeowner's insurance), mortgage insurance (PMI or MIP for FHA loans), HOA dues, or loan origination fees. For a true monthly PITI estimate, add those costs manually on top of the P&I figure shown here, and consult your loan contract for the official payment schedule.