Mortgage Calculator (Instant)

Most mortgage calculators hide the actual answer behind a “Calculate” button. This one updates as you type. By the time you finish entering the home price, the monthly payment is already on screen.

What This Calculator Does

Enter home price, down payment, loan term (15/20/30 years), and interest rate. The calculator returns:

• Monthly P&I (principal and interest)
• Monthly PMI (if down payment < 20%)
• Monthly property tax (state-default rate, override to your county)
• Monthly homeowners insurance (default $1,800/year, override)
• Total monthly payment with all four components
• Loan amount and total interest paid over the term
• Amortization schedule (toggle “show schedule” for year-by-year detail)

Why “Instant” Matters

The “instant” in this calculator means:

• No submit button — the result updates on every keystroke
• No page reload — calculation runs entirely in your browser
• No round-trip to a server — works offline once loaded
• No “schedule a call” popups — the answer is the answer

This is built for buyers who want to compare 5-10 scenarios in a row (15-year vs 30-year, 5% down vs 20% down, today’s rate vs rate +0.5%) without clicking submit 50 times.

Quick Example: $400,000 Home, 20% Down, 30-Year at 6.5%

• Home price: $400,000
• Down payment: $80,000 (20% — no PMI)
• Loan amount: $320,000
• Monthly P&I: $2,024
• Property tax (1.1% national avg): $367/month
• Homeowners insurance: $150/month
• Total monthly: $2,541

Same home with 5% down ($20,000) at the same rate:

• Loan amount: $380,000
• Monthly P&I: $2,403
• PMI (0.6% annual): $190/month
• Total monthly: $3,110

The down-payment gap is $60,000; the monthly gap is $569. The calculator shows both scenarios side-by-side for direct comparison.

Amortization Schedule

The full schedule shows:

• Each month’s principal, interest, and remaining balance
• Cumulative interest paid through any year
• The break-even year — when your cumulative principal payments exceed interest

For a 30-year loan at 6.5%, the break-even is around year 18-19. Before that, the majority of each payment is interest. The calculator visualizes this as a stacked bar chart.

Property Tax Variation by State

The default tax rate is the U.S. national average (1.1%). Override with your state’s actual rate:

• Hawaii: 0.32%
• Alabama: 0.39%
• Colorado: 0.55%
• Texas: 2.23%
• New Jersey: 2.49%
• Illinois: 2.08%

The calculator accepts the override in either % or $/year form. The monthly line item updates immediately.

Limitations

• The calculator does not include HOA fees (set in the optional field if applicable)
• It does not include flood insurance (required in some FEMA zones)
• It assumes a fixed-rate loan; ARMs and balloon loans need a different model
• It does not pre-qualify you — that requires a hard credit pull and a lender review

Related Tools

• Loan Calculator — for non-mortgage loans
• FHA Loan Calculator Texas — government-insured loans
• Compound Interest Calculator — investment growth counterpart