Mortgage Calculator — Total Interest Over the Life of Your Loan
Calculate your monthly payment and total cost of homeownership
A $300,000 mortgage at 7% interest over 30 years costs $418,527 in total interest — more than the original loan amount. Monthly payment is $1,996. Total amount paid is $718,527 on a $300,000 loan. Making one extra monthly payment per year saves approximately $64,000 in interest and pays off the loan 4 years early.
A mortgage calculator shows the true total cost of a home loan including all interest paid over the loan term. Most homebuyers focus on the monthly payment without realizing the total interest cost often exceeds the original purchase price over a 30-year term. Understanding this helps evaluate whether extra payments are worth making.
Last updated: June 2026
💰 Affordability Check
| Year | Remaining Balance | Principal Paid | Interest Paid |
|---|---|---|---|
| 5 | $301,221 | $18,779 | $108,959 |
| 10 | $274,600 | $45,400 | $210,076 |
| 15 | $236,860 | $83,140 | $300,075 |
| 20 | $183,360 | $136,640 | $374,313 |
| 25 | $107,517 | $212,483 | $426,208 |
| 30 | $0 | $320,000 | $446,428 |
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Now What? Your Mortgage Action Plan
Affordability — Enter Income to Check
Enter your gross monthly income above to see whether this mortgage meets the 28% front-end ratio guideline used by most lenders. The 28% rule means your total monthly payment (principal, interest, taxes, insurance) should not exceed 28% of gross monthly income.
Down Payment — 20% (No PMI)
Your 20% down payment avoids PMI — a meaningful monthly saving. You also start with substantial equity which reduces risk if home values decline and improves your loan-to-value ratio for future refinancing.
💡 Total interest cost: $446,428 over 30 years —140% of your original loan amount. Making one extra mortgage payment per year reduces a 30-year mortgage by approximately 4-6 years and saves tens of thousands in interest.
Your Next 4 Actions
You will pay $446,428 in interest over 30 years — consider making one extra principal payment per year to reduce this by 4-6 years
Refinance if rates drop 1%+ below your current rate — model the break-even point before deciding
Build a home maintenance reserve of 1-2% of home value annually ($500/month) — unexpected repairs are the most common cause of financial stress for new homeowners
Verify your property tax and insurance estimates — these can change annually and affect your true monthly payment
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For educational purposes only. Not financial advice. Actual rates and costs may vary. Consult a mortgage professional.