Amortization Calculator
Enter your loan details to get a complete month-by-month amortization schedule, see exactly how your payments split between principal and interest, and discover how much you save with extra payments.
▶Notes & assumptions
Amortization Schedule
| Year | Payment | Principal | Interest | Balance | Detail |
|---|---|---|---|---|---|
| Year 1 | $21,584 | $3,684 | $17,900 | $296,316 | |
| Year 2 | $21,584 | $3,911 | $17,673 | $292,405 | |
| Year 3 | $21,584 | $4,152 | $17,431 | $288,252 | |
| Year 4 | $21,584 | $4,409 | $17,175 | $283,844 | |
| Year 5 | $21,584 | $4,681 | $16,903 | $279,163 | |
| Year 6 | $21,584 | $4,969 | $16,615 | $274,194 | |
| Year 7 | $21,584 | $5,276 | $16,308 | $268,918 | |
| Year 8 | $21,584 | $5,601 | $15,983 | $263,317 | |
| Year 9 | $21,584 | $5,947 | $15,637 | $257,371 | |
| Year 10 | $21,584 | $6,313 | $15,270 | $251,057 | |
| Year 11 | $21,584 | $6,703 | $14,881 | $244,354 | |
| Year 12 | $21,584 | $7,116 | $14,468 | $237,238 | |
| Year 13 | $21,584 | $7,555 | $14,029 | $229,683 | |
| Year 14 | $21,584 | $8,021 | $13,563 | $221,662 | |
| Year 15 | $21,584 | $8,516 | $13,068 | $213,147 | |
| Year 16 | $21,584 | $9,041 | $12,543 | $204,106 | |
| Year 17 | $21,584 | $9,599 | $11,985 | $194,507 | |
| Year 18 | $21,584 | $10,191 | $11,393 | $184,316 | |
| Year 19 | $21,584 | $10,819 | $10,765 | $173,497 | |
| Year 20 | $21,584 | $11,486 | $10,097 | $162,011 | |
| Year 21 | $21,584 | $12,195 | $9,389 | $149,816 | |
| Year 22 | $21,584 | $12,947 | $8,637 | $136,869 | |
| Year 23 | $21,584 | $13,746 | $7,838 | $123,123 | |
| Year 24 | $21,584 | $14,593 | $6,990 | $108,530 | |
| Year 25 | $21,584 | $15,494 | $6,090 | $93,036 | |
| Year 26 | $21,584 | $16,449 | $5,135 | $76,587 | |
| Year 27 | $21,584 | $17,464 | $4,120 | $59,124 | |
| Year 28 | $21,584 | $18,541 | $3,043 | $40,583 | |
| Year 29 | $21,584 | $19,684 | $1,899 | $20,898 | |
| Year 30 | $21,584 | $20,898 | $685 | $0 |
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How to Use This Calculator
Tab "Full Schedule"
Enter your loan amount, annual interest rate, and loan term in years. The calculator instantly shows your monthly payment and generates a complete amortization schedule, grouped by year. Click Show on any year to expand the month-by-month detail. Use Download CSV to export the full schedule to a spreadsheet.
Tab "Principal vs Interest"
Same inputs as above, but the output focuses on how the payment composition changes over time. In year 1 of a 30-year mortgage at 6%, over 85% of every payment goes to interest. By year 25, that figure flips — most goes to principal. The calculator highlights the exact crossover month when principal first exceeds interest.
Tab "Extra Payments"
Add optional extra monthly payments, an annual lump sum (e.g. a tax refund), or a one-time payment at a specific month. The calculator compares your original and accelerated schedules side by side, showing total interest saved and how many years/months you cut from the loan term.
The Amortization Formula
M = P × [r(1+r)^n] / [(1+r)^n − 1]
Where:
M = monthly payment
P = principal loan amount
r = monthly interest rate (annual rate ÷ 12)
n = total payments (years × 12)
Each month:
Interest = Remaining balance × r
Principal = M − Interest
New balance = Remaining balance − Principal
Total interest paid:
Total cost − Principal = (M × n) − P
The formula produces a fixed monthly payment. In month 1 most of that payment is interest; in the final month almost all of it is principal. This is why amortized loans feel "expensive" early on — you are paying interest on the full balance.
Worked Examples
Example 1: $300,000 mortgage at 6% for 30 years
The most common scenario — a standard 30-year fixed-rate home loan.
After 12 months you have paid $21,583 — but only $3,723 of that reduced your balance. The remaining $17,860 was interest. This is the core insight amortization reveals.
Example 2: Same loan + $200/month extra
Adding $200 extra to every payment — a modest increase of about 11%.
A small extra payment has an outsized effect because every dollar of extra principal reduces the balance on which future interest is charged. The savings compound across hundreds of future payment cycles.
Example 3: $50,000 car loan at 5.5% for 5 years
A shorter-term, lower-rate loan — typical for vehicle financing.
Shorter terms and lower rates mean the crossover (principal > interest) happens much earlier — around month 30 for this loan, compared to month 252 for the 30-year mortgage above.
Key Amortization Concepts
| Concept | What it means |
|---|---|
| Amortization | The process of spreading loan payments over time so each payment covers both interest and principal |
| Principal | The original loan balance; the portion of each payment that reduces what you owe |
| Interest | The cost of borrowing; charged monthly on the remaining balance |
| Amortization schedule | A full table showing every payment, its principal/interest split, and the remaining balance |
| Crossover point | The month when your principal payment first exceeds your interest payment |
| Prepayment | Any extra payment applied directly to principal, reducing future interest |
| Negative amortization | When payments are too small to cover interest — balance grows instead of shrinking (not this calculator) |
| Loan term | Total length of the loan in years; longer term = lower monthly payment but more total interest |
Why Extra Payments Are So Powerful
Every extra dollar you pay toward principal eliminates all the future interest that would have been charged on that dollar. On a 30-year mortgage at 6%, each $1 you pay early saves roughly $1.15 in interest over the remaining term — effectively a guaranteed 6% return.
The earlier in the loan you make extra payments, the greater the compounding effect. A $5,000 lump sum payment in month 12 saves significantly more than the same payment in month 200, because it avoids more future interest cycles.
Common strategies include: rounding up your payment to the nearest $100, making one extra payment per year (equivalent to bi-weekly payments), applying bonuses or tax refunds as lump sums, and refinancing to a shorter term when rates drop.