Scheduled monthly payment
$1,847.15
Amortization Calculator
Generate a month-by-month amortization schedule for any fixed-rate loan. See each payment split into principal and interest, chart it, and export to CSV.
Key Terms (Click to expand)
Amortization schedule
A month-by-month breakdown of payment amount, interest, principal, and remaining balance.
Principal
The amount borrowed before interest charges.
Interest portion
The cost of borrowing for a payment period based on the outstanding balance.
Extra payment
Additional monthly amount applied directly to principal to shorten payoff and reduce interest.
Remaining balance
The unpaid principal after each monthly payment is applied.
Tool
Total interest
$364,974.58
Total repayment
$664,974.58
Estimated payoff
360 payments
Amortization detail breakdown
| Loan amount | $300,000.00 |
|---|---|
| Loan term (months) | 360 |
| Annual interest rate | 6.25% |
| Extra payment (monthly) | $0.00 |
| Interest saved | $0.00 |
Amortization schedule
Methodology
The calculator first computes the scheduled monthly payment, then iterates month-by-month:
M = P * [r(1 + r)^n] / [(1 + r)^n - 1]
- P = loan amount
- r = monthly interest rate (annual rate / 12)
- n = total number of months in the loan term
- Each row computes interest from current balance, applies principal, and updates remaining balance.
Using This Tool Well
When to use this tool
- First-year interest audit: on a $300,000 loan at 6% for 30 years, the first payment is about $1,799 and roughly $1,500 of it is interest.
- Extra-payment plan: test whether a recurring $300 principal payment materially shortens a mortgage before committing the money every month.
- Statement check: compare the expected interest and principal split for a specific month when a lender or servicer statement looks surprising.
How to read the result
Read the schedule left to right: previous balance drives interest first, and whatever is left from the payment reduces principal. The early rows are interest-heavy by design. The useful question is whether extra principal, a shorter term, or a different loan structure changes that curve enough to matter.
Common mistakes
- Entering a one-time prepayment as recurring: a $500 one-off entered as monthly extra payment turns into a $6,000-per-year plan and can make payoff look far faster than reality.
- Ignoring payment rules: a $300 monthly extra payment on a $320,000 30-year loan at 5.75% can save about $115,000 in interest only if the servicer applies it to principal as modeled.
- Expecting penny-perfect statements: rounding can shift the final row by $0.01 or a few cents because this schedule force-closes the balance to zero on the last payment.
Reviewed by Leonardo, Software Engineer
Last reviewed June 23, 2026
Premises and Limitations
- This schedule assumes a fixed interest rate and monthly payment cadence.
- Extra payment is modeled as recurring monthly principal prepayment.
- Actual servicer rules may apply payments differently or include additional fees.
FAQ
What is an amortization schedule?
It is a payment-by-payment breakdown showing how each installment splits into principal and interest.
Why is interest higher at the beginning?
Early payments are calculated on a larger balance, so interest portion starts higher and falls over time.
What happens if I add extra monthly payments?
Extra payments reduce principal faster, which can shorten payoff time and lower total interest.