Mortgage Amortization Calculator
Generate a complete month-by-month or year-by-year mortgage amortization schedule. See exactly how each payment is split between principal and interest, watch your balance decrease over time, and discover how extra monthly payments can save you thousands in interest and years off your mortgage.
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How It Works
The standard amortization formula calculates equal monthly payments. Each payment covers interest on the remaining balance plus a portion of principal. The schedule shows this breakdown for every single payment.
M = P x r(1+r)^n / [(1+r)^n - 1]$300K at 6.5% for 30yr = $1,896/moEach month interest = remaining balance x monthly rate. As the balance decreases, the interest portion shrinks and more goes to principal. Month 1 of $300K at 6.5%: interest = $300K x 0.005417 = $1,625.
Interest = Balance x (annual_rate / 12)Month 1: $300K x 6.5%/12 = $1,625 interestPrincipal = total payment minus interest. In early months this is small. Over time it grows as interest decreases. By the last year, nearly the entire payment goes to principal.
Principal = Payment - InterestMonth 1: $1,896 - $1,625 = $271 to principalExtra monthly payments go entirely to principal. This reduces the balance faster, which reduces future interest charges, creating a compounding savings effect. Enter any extra amount to see the impact on your full schedule.
New balance = old balance - (regular principal + extra)$300K, +$200/mo extra = save $67K interest, 7yr soonerThe yearly view aggregates 12 months into annual totals. Shows total interest paid that year, total principal paid, starting and ending balance. Useful for tax planning and tracking long-term progress.
Year total = sum of 12 monthly valuesYear 1: $19,374 interest, $3,375 principal on $300KThe crossover is the month when principal portion first exceeds interest. For a 30-year mortgage at 6.5%, this happens around month 216 (year 18). For 15-year at 6%, it is around month 60 (year 5).
When Payment - Balance x r > Balance x r$300K, 6.5%, 30yr: crossover at ~month 216Quick Reference
Common examples — verify instantly above.
$300K, 6.5%, 30yr
Monthly payment
$1,896/mo
Month 1 interest
$300K at 6.5%
$1,625
Month 1 principal
$300K at 6.5%
$271
Total interest
$300K, 6.5%, 30yr
$382,633
Year 1 principal
$300K, 6.5%, 30yr
$3,375
Crossover month
30yr at 6.5%
~Month 216
+$200 extra/mo
$300K, 6.5%, 30yr
Save $67K, 7yr
15yr vs 30yr
$300K at 6%
Save $165K interest
Tips & Shortcuts
Toggle between Monthly and Yearly views to see the level of detail you need. Yearly is best for planning; monthly for verifying individual payments.
Enter extra monthly payments to see exactly how many months and dollars you save. Even small amounts compound over the life of a 30-year loan.
The first year of a 30-year mortgage at 6.5% is about 85% interest. By year 20, it flips to 85% principal. Understanding this helps with financial planning.
Use this schedule to verify your lender statements. The monthly interest should match: balance x annual rate / 12.
Print or save your schedule for tax purposes. Mortgage interest is tax-deductible and the schedule shows exactly how much you paid each year.
Compare 15-year vs 30-year schedules side by side. The 15-year has higher payments but dramatically less total interest and a faster crossover point.
Common Mistakes to Avoid
Expecting equal principal in every payment
In a standard amortizing loan, principal increases each month while interest decreases. The payment stays the same but the split changes. This is normal and by design.
Ignoring the interest-to-principal ratio in early years
In the first years of a 30-year mortgage, over 80% of each payment is interest. Awareness of this ratio helps set realistic expectations about equity building.
Not accounting for extra payments in the schedule
If you make extra payments, your actual schedule differs from the original. Regenerate the schedule with your extra payment amount to see the real impact.
Using the wrong compounding period
Most US mortgages use monthly compounding. Canadian mortgages use semi-annual. Make sure the amortization schedule matches your specific loan terms.
Confusing amortization with simple interest
Amortization recalculates interest on the declining balance each month. Simple interest would charge the same interest regardless of payments made.
Not updating the schedule after refinancing
If you refinance, the old schedule no longer applies. Generate a new schedule with the new rate, balance, and term to track your payments accurately.
Frequently Asked Questions
An amortization schedule is a complete table showing every payment over the life of a mortgage. Each row breaks down how much of that payment goes to interest versus principal, and shows the remaining balance. Early payments are mostly interest; later payments are mostly principal.
Interest is calculated on the outstanding balance. When the balance is highest (early in the loan), the interest portion is largest. As you pay down the principal, interest decreases and more of each payment goes to reducing the balance.
Extra payments go directly to principal, reducing the balance faster. This means less interest accrues in future months, shortening the total loan term. Even $100 per month extra on a $300,000 mortgage can save over $40,000 in interest and several years.
The monthly view shows every individual payment with its exact interest and principal split. The yearly view summarizes each year total interest paid, total principal paid, and ending balance. Use yearly for an overview, monthly for exact payment details.
This crossover point depends on the interest rate and term. For a typical 30-year mortgage at 6.5%, the crossover happens around year 18. For a 15-year mortgage, it happens much sooner, around year 5 to 7.
Yes. Any fixed-rate amortized loan follows the same math. Enter the loan amount, interest rate, and term to generate a schedule for auto loans, personal loans, or student loans.
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