Mortgage Calculator
Estimate your monthly mortgage payment, total interest and total repayment from home price, down payment, rate and term.
How to Use
- Enter the home price and how much you're putting down — leave the down payment at 0 to estimate financing the full price.
- Enter the annual interest rate (the rate on your loan note, not an APR that includes fees/points) you're estimating with, and the loan term in years (commonly 15 or 30).
- The result shows the loan amount financed, the estimated monthly principal + interest payment, total interest, and total repayment over the full term.
Formula
- Loan amount
- loan_amount = home_price − down_payment
- Monthly rate
- monthly_rate = annual interest rate ÷ 100 ÷ 12
- Monthly payment
- payment = loan_amount × monthly_rate ÷ (1 − (1 + monthly_rate)^−months)
- Total repayment
- total_repayment = payment × months
- Total interest
- total_interest = total_repayment − loan_amount
Worked Example
A $300,000 home with a $60,000 (20%) down payment, a 6.5% annual interest rate, 30-year term.
- Loan amount: $300,000 − $60,000 = $240,000
- Monthly rate: 6.5 ÷ 100 ÷ 12 ≈ 0.005417
- Monthly payment: $240,000 × 0.005417 ÷ (1 − 1.005417⁻³⁶⁰) ≈ $1,516.96
- Total repayment: $1,516.96 × 360 ≈ $546,106.77
- Total interest: $546,106.77 − $240,000 ≈ $306,106.77
Result: Loan amount financed: $240,000.00 / Estimated monthly payment (principal + interest): $1,516.96 / Total interest: $306,106.77 / Total repayment: $546,106.77
About This Tool
What this tool does
This calculator estimates the monthly principal + interest payment on a fixed-rate mortgage, along with the total interest and total amount repaid over the full loan term.
When to use it
Use it to compare how a different down payment, rate, or term changes your estimated monthly payment before you talk to a lender, or to get a rough sense of a mortgage's total cost over its life.
What the result means
The loan amount financed is the home price minus your down payment — the actual amount being borrowed. The monthly payment shown is principal and interest only.
Assumptions & limitations
The rate you enter should be the loan's annual (note) interest rate, not its APR. APR is a broader, government-mandated disclosure that folds in lender fees and points on top of the interest rate, so it's not the number your lender actually applies to the principal each month — using an APR here would overstate your real principal + interest payment. This estimate covers principal and interest only — it does NOT include property tax, homeowners insurance, private mortgage insurance (PMI, typically required with less than 20% down), or HOA fees, all of which are commonly rolled into a real monthly mortgage payment and can add a substantial amount on top of this estimate. This tool is not a loan offer, pre-qualification, or lending recommendation, and Calcoryn does not endorse or recommend any specific lender — always get an official Loan Estimate from a real lender before making a decision.