480-Month Amortization Schedule
See every month of your 30-year (or 40-year) mortgage — principal, interest, PMI, and extra payments. Interactive charts show the impact of paying extra principal and when your loan balance crosses key thresholds.
Amortization Charts
$187,500 loan at 7% over 30 years — with $100/mo extra principal starting in Year 1.
The balance chart shows two lines when extra principal is applied: the standard payoff schedule vs. the accelerated payoff. The shaded area between them represents your interest savings.
Should You Pay Extra Principal?
The amortization tab helps you evaluate both sides of this common real estate debate.
Pros of Extra Principal
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Guaranteed Return
Every dollar of extra principal saves you the interest rate on that dollar. At 7%, that's a guaranteed 7% return — risk-free.
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Massive Interest Savings
On a $187,500 loan at 7%, paying $100/mo extra saves over $50,000 in total interest over the life of the loan and shaves years off the payoff date.
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Faster Equity Building
More equity means more options: refinance, HELOC, or sell with a larger net proceeds check.
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PMI Elimination
If you're paying PMI, extra principal helps you hit the LTV threshold to drop it faster.
Cons of Extra Principal
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No Cash Flow Improvement
Your required monthly payment stays the same. Extra principal reduces balance but doesn't reduce next month's payment — it only shortens the term.
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Equity Gets Locked Up
Extra principal builds equity, but equity in a property is illiquid. Accessing it requires a refinance or HELOC — both have costs and qualification requirements.
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Opportunity Cost
That $100/mo could be invested elsewhere. If you can earn more than your mortgage rate investing in other deals, the extra principal costs you the difference.
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Less Cash Reserve
Extra principal payments reduce your cash reserves. In an emergency, you can't easily get that money back.
TWGREDAS™ shows you both sides. Model different extra principal amounts and see exactly how they affect your total interest paid, payoff date, equity trajectory, and return metrics — so you can make an informed decision for each deal.
The Amortization Table
A full 480-month schedule with year-by-year navigation, PMI tracking, and per-month payment overrides.
| Month | Balance | Payment | Extra | Interest | Principal | End Bal |
|---|---|---|---|---|---|---|
| 1 Apr 2026 | $187,500 | $1,247 | $100 | $1,094 | $254 | $187,246 |
| 2 Apr 2026 | $187,246 | $1,247 | $100 | $1,092 | $255 | $186,991 |
| 3 Apr 2026 | $186,991 | $1,247 | $100 | $1,091 | $257 | $186,734 |
| 4 Apr 2026 | $186,734 | $1,247 | $100 | $1,089 | $258 | $186,476 |
| 5 Apr 2026 | $186,476 | $1,247 | $100 | $1,088 | $260 | $186,217 |
| 6 Apr 2026 | $186,217 | $1,247 | $100 | $1,086 | $261 | $185,955 |
| ... months 7-12 ... | ||||||
| Year 1 Totals | $23,078 | $1,200 | $20,085 | $4,193 | ||
What Each Column Shows
Month number (1-480) with the actual calendar date if you've set a purchase date on the property.
The loan balance at the start of this month, before any payment is applied.
Your fixed monthly principal and interest payment (P&I).
Additional principal you choose to pay each month. Click any cell to set or change the amount. Highlighted in amber when active.
The portion of your payment that goes to the lender as interest. This shrinks every month as your balance decreases.
Regular principal plus extra principal. This is how much your loan balance actually decreases this month.
Your loan balance at end of month. PMI badge appears when balance drops below the PMI threshold.
Flexible Extra Principal Payments
Apply extra principal for a single month, a range of months, or the entire loan — all from a simple bulk tool.
Single Entry for All 480 Months
Want to pay an extra $100/mo for the entire loan? Enter it once and it applies to every month automatically.
Custom Date Range
Apply extra principal for a specific period — like $200/mo for the first 5 years, then stop. Set start and end months.
Per-Month Overrides
Click any extra principal cell to set a unique amount for that specific month. Perfect for modeling lump-sum payments or irregular contributions.
Bulk Extra Principal
Review Your Extra Payments
Both the amortization tab and the overrides tab let you see a filtered list of only the cells you've changed.
Extra Principal Only Filter
Toggle the "Extra principal only" filter on the amortization table to show just the months where you've set extra payments. Quickly review your entire extra principal schedule without scrolling through 480 months.
Manage All Overrides
The manage overrides page lists every change you've made — including extra principal, rent overrides, expense changes, and more. Delete individual entries or clear everything to start fresh.
Explore More Features
Dive deeper into what makes TWGREDAS™ the most complete deal analysis tool.
Included with All Apps
Property Database
30+ financial fields organized into 9 categories with auto-save and full change history.
Property Classification
Tag properties by investment strategy and property type. Filter and sort your entire portfolio.
Real-Time Calculations
27 key metrics across 5 categories computed instantly as you type, with clickable walkthroughs.
Portfolio Dashboard
Portfolio highlights, property cards, strategy and type breakdowns, overview charts, and cross-app features.
Included with Purchase of Deal Analyzer
Four-Stream Breakdown
See appreciation, cash flow, debt paydown, and tax benefits as both dollars (RIDQ™) and percentages (ROIQ™).
Analysis Dashboard
The TWGREDAS™ card, 6 input sections, and 9 interactive charts that update as you type.
Multi-Year Projections
Project all 80+ metrics across 40 years. See how returns compound and accelerate over time.
Override System
Click any cell to override its value. Changes cascade forward and recalculate all downstream metrics.
Scenario Modeling
Model rent bumps, tax increases, renovations, or any scenario with month-level granularity.
Return Quadrants™
RIDQ™, ROIQ™, ROEQ™, and ROTNEQ™ with year navigation and reserve adjustments.
Yearly Summaries
All 40 years in one table: value, rent, cash flow, equity, RIDQ™, ROIQ™, cap rate, and IRR.
IRR Tables
Internal Rate of Return before and after taxes for every year from 1 to 40.
See Every Month of Your Mortgage
480 months of detail, interactive charts, PMI tracking, and full extra principal modeling. Know exactly where your money goes.