Amortization Calculator See how your loan payments break down over time — principal, interest, and balance — with extra p...
Amortization Calculator
See how your loan payments break down over time — principal, interest, and balance — with extra payment analysis and printable schedules.
Amortization** is the process of gradually paying off a loan with fixed payments over time.
Formula**:
$$PMT = P \frac{r(1+r)^n}{(1+r)^n - 1}$$
Where: • $P$ = loan principal • $r$ = monthly interest rate (annual ÷ 12) • $n$ = number of payments
Year 1 Example** ($300K, 6.8%, 30 yr): • Payment 1: $1,952 → $223 principal, $1,729 interest • Payment 12: $1,952 → $239 principal, $1,713 interest • By Year 10: $500+ principal per payment
✅ Pro Tip**: Extra payments early save the most — because interest is calculated on the *remaining balance*.
⚠️ Common mistakes:
- Missing the front-load effect** — 70% of Year 1 payment is interest
- Prepayment penalties** — Some loans charge 1–2% for early payoff (check your contract!)
- “Bi-weekly” scams** — Third-party services that charge fees to split your payment (do it yourself for free)
- Refinancing too often** — Resetting the clock adds $100K+ in interest vs. sticking with extra payments
✅ Optimal Strategy**:
- Make extra payments *with* your regular payment (specify “apply to principal”)
- Refinance only if rate drop ≥1% AND break-even <2 years
- Avoid loans with precomputed interest (Rule of 78s)
| Loan | Payment | Total Interest | With $200/mo Extra |
|---|---|---|---|
| $300K @ 6.8%, 30 yr | $1,952 | $402,720 | 22.3 yrs, $338K int (save $64K) |
| $25K @ 7.2%, 5 yr | $500 | $5,000 | 4.1 yrs, $4,200 int (save $800) |
| Bi-weekly (same $) | 26 half-payments | — | 7.2 yrs faster, $83K saved |
📉 Interest Front-Loading** (30-yr mortgage):
- Year 1: 88% of payments = interest
- Year 10: 65% interest
- Year 20: 35% interest
- Year 30: 1% interest
➡️ Standard
Enter loan amount, rate, and term to generate full amortization schedule.
➡️ Extra Payments
Test lump sums (tax refund) or recurring extra payments (bonus plan).
➡️ Compare Loans
See side-by-side impact of refinancing or different loan offers.
Features**:
- Interactive SVG amortization curve
- Printable year-by-year table
- “Months saved” and “Interest saved” metrics
- Mobile-friendly scrolling table
Note: Assumes fixed rate, no fees, on-time payments. For ARMs, model manually.