Mortgage Calculator
Use your own numbers after reviewing the formula and worked example.
Quick answer
This scenario uses a $300,000 principal balance, a 6.5% fixed annual rate and a 30-year term as a benchmark.
Formula or method
Keep units, percentages and time periods consistent. The formula is useful as a transparent check on the calculator result and helps explain why changing one input changes the answer.
Step-by-step
- Use $300,000 as principal.
- Convert 6.5% to a monthly rate.
- Use 360 monthly payments.
- Calculate payment and total scheduled interest.
Worked example
The payment is about $1,896.20. Across 360 payments, scheduled principal and interest total about $682,633, including roughly $382,633 of interest.
How to interpret the result
This is not the complete housing bill; taxes, insurance, mortgage insurance and HOA dues may be additional.
When the answer is used for a purchase, loan, payroll decision, construction order, school grade, health estimate or other real-world choice, verify the assumptions that matter in that context. Accurate arithmetic still depends on accurate inputs.
Common mistakes
- Using home price instead of amount financed.
- Assuming the answer includes taxes and insurance.
- Ignoring fees or adjustable-rate features.
Frequently asked questions
Would a $300,000 home have a $300,000 mortgage?
Not necessarily; principal is the amount actually financed.
Can extra payments reduce the interest?
Yes, when applied to principal they can lower future interest.
Does one rate change affect every borrower equally?
No; the dollar effect depends on balance and term.