Amortization Calculator
See your full loan payment schedule — principal, interest, and balance every month
How Amortization Works
The crossover point — where your monthly principal exceeds your monthly interest — happens around year 19 on a 30-year mortgage at 7%. Before that, more than half your payment goes to interest.
Impact of Extra Payments on a $300,000 Mortgage (7%, 30yr)
| Extra/Month | Total Interest | Interest Saved | Payoff | Time Saved |
|---|---|---|---|---|
| $0 (base) | $418,527 | — | 30 years | — |
| $100/mo | $375,611 | $42,916 | 26 yrs 5 mo | 3 yrs 7 mo |
| $200/mo | $344,021 | $74,506 | 23 yrs 9 mo | 6 yrs 3 mo |
| $300/mo | $319,107 | $99,420 | 21 yrs 8 mo | 8 yrs 4 mo |
| $500/mo | $280,063 | $138,464 | 18 yrs 5 mo | 11 yrs 7 mo |
| $1,000/mo | $224,107 | $194,420 | 13 yrs 10 mo | 16 yrs 2 mo |
Base payment $1,996/month. Extra payments applied to principal each month.
15-Year vs 30-Year Mortgage
| 30-Year at 7% | 15-Year at 6.5% | Difference | |
|---|---|---|---|
| Loan amount | $300,000 | $300,000 | — |
| Monthly payment | $1,996 | $2,613 | +$617/mo |
| Total interest paid | $418,527 | $170,340 | Save $248,187 |
| Total paid | $718,527 | $470,340 | Save $248,187 |
| Equity after 5 years | ~$18,000 | ~$82,000 | +$64,000 |
Frequently Asked Questions
What is an amortization schedule?
A table showing every loan payment split into principal (reduces balance) and interest (cost of borrowing). Early payments go mostly to interest; later payments go mostly to principal. The amortization table above shows this month by month or year by year.
Why do early mortgage payments go mostly to interest?
Interest is calculated on the remaining balance. At month 1, you owe the full $300,000, so 7% annual = $1,750 in interest that month alone. As your balance falls, so does the interest portion — but this takes years on a 30-year loan.
How much interest do I save with extra payments?
On a $300,000 mortgage at 7%, paying $200/month extra saves about $74,500 in interest and cuts 6+ years off the loan. Use the extra payment field above to calculate your exact savings.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage saves enormous interest (often $200,000+) and builds equity faster, but monthly payments are about 30% higher. Choose 30-year if cash flow is tight; choose 15-year if you can afford the higher payment and want to pay off faster.
What does "fully amortizing" mean?
A fully amortizing loan means each payment covers interest plus some principal, so the balance reaches exactly $0 on the final payment date. Most mortgages, car loans, and personal loans are fully amortizing. Contrast with interest-only loans where balance never decreases.