| Year | Principal Paid ($) | Interest Paid ($) | Ending Balance ($) |
|---|---|---|---|
| {{ r.year }} | {{ format(r.principalYear) }} | {{ format(r.interestYear) }} | {{ format(r.balance) }} |
| Month | Principal ($) | Interest ($) | Payment ($) | Balance ($) |
|---|---|---|---|---|
| {{ r.period }} | {{ format(r.principal) }} | {{ format(r.interest) }} | {{ format(r.payment) }} | {{ format(r.balance) }} |
Auto-loan amortisation spreads the cost of a vehicle across equal instalments. Each payment covers interest, calculated on the remaining balance, and repays part of the principal, steadily shrinking that balance and reducing future interest. Understanding this interplay helps you gauge the real cost of borrowing and the benefit of paying faster.
This calculator models that amortisation in real time. Enter the loan amount, annual interest rate, and term, then optionally add a down payment or extra monthly contribution. A reactive engine instantly computes the required payment, builds a month-by-month schedule, and renders visual comparisons of principal versus interest and the declining balance.
Use it to compare offers before visiting a dealership, testing how different rates, down payments, terms, or extra payments affect monthly affordability and lifetime cost, and to see precisely when the loan might be cleared ahead of schedule. Figures are estimates only; consult a qualified adviser for personalised guidance.
Calculations follow standard amortisation theory and the time-value-of-money principle. Interest accrues on the current outstanding principal at a fixed monthly rate, while repayment of principal reduces that base. Additional payments shorten the schedule because interest is always computed on the reduced balance.
| Symbol | Definition | Typical Range | Sensitivity |
|---|---|---|---|
| P | Principal after down payment | $1 000 – $150 000 | Directly proportional |
| i | Monthly interest rate | 0 % – 1 % (APR/12) | Exponential impact |
| n | Total months | 12 – 120 | Exponential impact |
| E | Extra monthly payment | $0 – $1 000 | High for long terms |
| M | Monthly payment result | Calculated | ― |
| APR Band | Description |
|---|---|
| < 3 % | Low-cost credit |
| 3 – 6 % | Standard market rate |
| > 6 % | High-cost borrowing |
Example: P = 30 000, i = 0.045 / 12 = 0.00375, n = 60, E = 0.
Monthly payment is $559.29; total interest after 60 months is $3 557.43.
The computation is O(n) and executes instantly in modern browsers. A loop-limit guard and fixed-precision rounding prevent cumulative floating-point drift.
Follow this flow from top to bottom; calculations refresh automatically.
The calculator uses exact amortisation formulas and eight-decimal internal precision, so rounding is the only minor source of variance.
An amount added to every monthly instalment. One-off lump-sum prepayments are not yet supported.
When principal reaches zero before the planned term—often due to extra payments—the loop stops and schedules adjust automatically.
No. All calculations run locally in your browser, and nothing is transmitted or saved.
Not directly. Enter the highest expected rate for a conservative estimate, or rerun scenarios with different rates.