# PayCalc Pro

> Free professional-grade loan payment calculators with real-time amortization schedules, interest rate sensitivity analysis, and expert financial insights.

PayCalc Pro is a free web-based financial calculator suite for mortgage, auto loan, and personal loan payments. All calculations use the standard amortization formula: M = P × [r(1+r)^n] / [(1+r)^n – 1].

## Calculators

- [Mortgage Payment Calculator](https://paycalc.loan/mortgage-payment): Calculate monthly mortgage payments with amortization schedule, interest rate sensitivity, and total cost breakdown.
- [Auto Loan Calculator](https://paycalc.loan/auto-loan-payment): Estimate car payments including trade-in value, sales tax, and depreciation analysis.
- [Personal Loan Calculator](https://paycalc.loan/personal-loan-payment): Calculate personal loan payments for debt consolidation, home improvement, or medical expenses.
- [Amortization Schedule Generator](https://paycalc.loan/amortization-schedule): Generate month-by-month amortization tables with principal vs interest breakdown and CSV export.
- [Extra Payment Calculator](https://paycalc.loan/extra-payment): See how extra payments save interest and reduce loan term with side-by-side comparison.
- [Loan Comparison Tool](https://paycalc.loan/compare): Compare two loans side-by-side on monthly payment, total interest, and total cost.
- [Home Affordability Calculator](https://paycalc.loan/affordability): Find how much house you can afford based on income, debts, and DTI ratio.
- [Loan Glossary](https://paycalc.loan/glossary): Comprehensive glossary of 16 financial terms with definitions, examples, and links to related calculators.

## Key Financial Concepts

### Monthly Payment Formula
The standard amortization formula is M = P × [r(1+r)^n] / [(1+r)^n – 1], where M is the monthly payment, P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of payments. This formula is used by all major U.S. lenders and the Consumer Financial Protection Bureau (CFPB).

### Debt-to-Income Ratio (DTI)
DTI is total monthly debt payments divided by gross monthly income. Most lenders require DTI below 43%. The 28/36 rule recommends housing costs ≤28% and total debt ≤36% of gross income.

### Amortization
Amortization is the process of paying off a loan through scheduled payments over time. In early payments, most goes to interest. Over time, the principal portion increases. A $300,000 mortgage at 6.5% for 30 years has a monthly payment of $1,896, with $1,625 going to interest in month one.

### Extra Payments
Extra payments reduce principal faster, saving interest over the loan's life. An extra $100/month on a $300,000 mortgage at 6.5% saves approximately $60,000 in interest and nearly 5 years off the term.

### Private Mortgage Insurance (PMI)
PMI is required when the down payment is less than 20% (LTV > 80%). PMI costs 0.5–1% of the loan amount annually. It can be removed once LTV drops below 80%.

### Interest Rate vs APR
The interest rate is the cost of borrowing principal. APR includes the interest rate plus fees, giving a more complete cost picture. APR is always ≥ the interest rate.

## Example Calculations

- **$300,000 mortgage at 6.5% for 30 years**: Monthly payment = $1,896, Total interest = $382,633, Total cost = $682,633
- **$35,000 auto loan at 5.9% for 5 years**: Monthly payment = $676, Total interest = $5,564
- **$15,000 personal loan at 8.5% for 3 years**: Monthly payment = $474, Total interest = $2,051

## About

PayCalc Pro uses client-side calculations for instant, private results. No data is stored or transmitted. All formulas follow CFPB and Federal Reserve standards.