A mortgage spreads a large property purchase over many smaller payments. Each instalment covers interest on remaining debt and a portion of the principal. Over time, the balance shrinks while interest falls too. Understanding this amortization pattern helps you weigh costs, compare lenders, and see how extra payments accelerate ownership.
This calculator models amortization using payment frequency, interest rate, and loan tenure. It instantly updates totals, interest-principal ratios, and payoff date as you adjust values. Advanced options simulate extra payments, lump sums, and yearly taxes to reveal true long-term spending. Data never leaves your browser, ensuring confidentiality while experimenting with scenarios.
Whether you’re a first-time buyer, broker, or instructor, use it to plan refinancing strategies, gauge home-buying affordability, compare fixed versus variable offers, or demonstrate in workshops how adding just one extra payment a year shaves years off schedules and saves substantial interest; results are illustrative and not personalised financial advice.
Technical Details:
The tool runs entirely in–browser, combining form inputs with a reactive interface to compute amortization on each keystroke. A lightweight charting layer visualises balance versus interest across the schedule. No server call occurs, so loan figures remain private. The interface adapts to mobile and desktop, relying only on native Bootstrap utilities for responsiveness.
Intuitive Input Controls
Number, select, and toggle elements prevent invalid values and guide you through required fields.
Dynamic Summary
A live heading highlights periodic payment, principal-interest split, and percentage ratios instantly.
Amortization Table
A scrollable table lists every period with payment, interest, principal, and remaining balance columns.
Interactive Chart
A stacked area chart plots principal versus interest over time, helping you spot crossover points quickly.
Privacy-First Calculation
All math runs locally; figures never transmit or persist, safeguarding personal borrowing scenarios.
Calculations & Scoring:
The periodic payment P derives from the standard amortization formula:
P = L · [ r(1 + r)n ] / [ (1 + r)n − 1 ]Variables: L loan principal; r periodic rate; n total periods. Extra payments reduce L before the next cycle, shortening n dynamically. Lump sums apply at a specified period index. Interest for each period is balance × r; principal is P − interest. Data Privacy: every calculation runs on your device only.
Step-by-Step Guide:
Follow these steps to generate a personal amortization schedule.
- Enter the Loan amount in your currency.
- Input a numeric Down payment and pick
%or currency in the adjacent selector. - Type the annual Interest rate and select the Loan tenure in years.
- Click Advanced to expand extras; adjust Payment frequency, Extra payment, or Lump sum as required.
- Review the top Payment summary and scan the Amortization table for period-by-period details.
- Tweak any field to compare scenarios until the schedule meets your budget goals.
FAQ:
Quick answers to common questions.
Is my data stored?
No. All inputs stay in memory and disappear when you reload or close the page.
Can I use bi-weekly payments?
Yes. Choose Bi-weekly under Payment frequency to recalculate 26 periods per year.
Why does interest drop each period?
As principal falls, interest equals a smaller balance times the same periodic rate, so interest declines while principal rises.
How are extra payments applied?
Extra amounts reduce principal immediately, shortening the term and lowering total interest.
What happens with lump sums?
The lump sum subtracts from the outstanding balance at the specified period, recalculating subsequent payments on the new balance.
Troubleshooting:
Resolve common issues quickly.
- Payment shows NaN – Ensure all required fields contain numbers and no field is blank.
- Chart is empty – Scroll down; it renders only after a valid schedule exists.
- Lump sum never applies – Verify the period number is within the loan tenure.
- Totals seem too high – Check whether the down payment type is set to percent or currency.
- Advanced section collapses too soon – Click outside the form controls before collapsing to save changes.