Smart Mortgage Prepayment Calculator 🏠

Mobile-friendly web app for calculating mortgage prepayment schedules with smart statement parsing.

Features

✅ Mobile-responsive - Works perfectly on phones, tablets, and desktop
✅ Camera upload - Take a photo of your mortgage statement
✅ Smart OCR - Automatically extract principal, rate, escrow, and extra payments
✅ Multiple bank formats - Parses various statement layouts
✅ Prepayment scenarios - Model extra monthly payments and lump sums
✅ Visual summary - See payoff date and interest saved at a glance
✅ Detailed schedule - Month-by-month breakdown with chart
✅ CSV export - Download schedule for Excel/Sheets

Usage

Option 1: Upload Statement

1. Open index.html in a browser
2. Click "Take Photo" or "Choose File"
3. Select your mortgage statement (PDF or image)
4. Wait for OCR processing (~10-30 seconds)
5. Review extracted values (edit if needed)
6. Click "Calculate"

Option 2: Manual Entry

1. Open index.html in a browser
2. Enter mortgage details:
   • Current principal balance
   • Interest rate (%)
   • Remaining term (years)
   • Monthly escrow (taxes/insurance)
   • Extra monthly payment (optional)
   • One-time lump sum (optional)
3. Click "Calculate"

What It Calculates

Summary

• New payoff date with extra payments
• Years saved compared to standard schedule
• Total interest saved vs. original amortization
• Total amount paid (principal + interest)

Detailed Schedule

Monthly breakdown showing:

• Payment amount
• Principal portion
• Interest portion
• Extra payment applied
• Remaining balance

Chart

Visual graph of balance declining over time.

OCR Statement Parsing

The app looks for these patterns in uploaded statements:

Principal Balance:

• "Principal Balance: $..."
• "Remaining Balance: $..."
• "Current Balance: $..."

Interest Rate:

• "Interest Rate: X.XX%"
• "Rate: X.XX%"

Escrow:

• "Escrow: $..."
• "Tax & Insurance: $..."

Extra Payments:

• "Additional Principal: $..."
• "Extra Payment: $..."

If OCR doesn't find values, you can always enter them manually.

Technical Details

Technologies

• HTML/CSS/JavaScript - Single-file web app
• Tailwind CSS - Responsive styling
• Tesseract.js - OCR for image text extraction
• Chart.js - Balance chart visualization

Browser Support

• Chrome/Edge/Safari/Firefox (latest)
• iOS Safari (camera support)
• Android Chrome (camera support)

Limitations

• PDF OCR not yet implemented (use image for now)
• Accuracy depends on statement image quality
• Works best with clear, high-contrast photos

Deployment

Local

Just open index.html in any browser. No server needed!

Web Hosting

Upload index.html to any static host:

• GitHub Pages
• Netlify
• Vercel
• AWS S3
• Firebase Hosting

Example (GitHub Pages):

git init
git add index.html README.md
git commit -m "Add mortgage calculator"
git remote add origin https://github.com/yourusername/mortgage-calc.git
git push -u origin main

# Enable GitHub Pages in repo settings → Pages → Source: main branch

Custom Domain

1. Host on Netlify/Vercel
2. Add your custom domain (e.g., mortgage-calc.yourdomain.com)
3. SSL automatically configured

Future Enhancements

• PDF text extraction support
• Save calculations to browser storage
• Compare multiple scenarios side-by-side
• Refinance calculator
• Amortization chart (principal vs interest over time)
• Property tax and insurance inflation adjustments
• Biweekly payment calculator
• Print-friendly summary report

Examples

Example 1: Standard Mortgage

• Principal: $250,000
• Rate: 6.5%
• Term: 30 years
• Escrow: $500/mo
• Result: Payoff in Oct 2054, $355K total interest

Example 2: With Extra Payments

• Principal: $250,000
• Rate: 6.5%
• Term: 30 years
• Escrow: $500/mo
• Extra: $200/mo
• Result: Payoff in Feb 2048 (6.7 years earlier), $286K interest ($69K saved)

Example 3: With Lump Sum

• Principal: $250,000
• Rate: 6.5%
• Term: 30 years
• Escrow: $500/mo
• Extra monthly: $100/mo
• Lump sum: $10,000
• Result: Payoff in Apr 2049 (5.5 years earlier), $295K interest ($60K saved)

Tips for Best OCR Results

1. Good lighting - Avoid shadows
2. Flat surface - No wrinkles or curves
3. Clear focus - Sharp text, not blurry
4. High contrast - Dark text on light background
5. Straight alignment - Not tilted/rotated
6. Zoom in - Fill frame with relevant section

Support

If you encounter issues:

1. Try manual entry instead of OCR
2. Check browser console for errors
3. Ensure image is clear and well-lit
4. Use JPEG/PNG format (not HEIC on iPhone)

License

MIT License - Free to use and modify

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Built with ❤️ for homeowners taking control of their mortgages