Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For First Responders · Real-Estate Analyzer

Real-Estate Analyzer for a retirement fund

Built for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field. Simulate a retirement fund live below — adjust the inputs and watch it respond, right in your browser.

Amortization

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Loan / Mortgage AmortizationLive

where each payment goes

Controls

Presets

Loan amount ($)

Interest rate (APR)

Term (years)

A fixed-rate loan has a level monthly payment, but its split shifts over time: early payments are mostly interest, later ones mostly principal. That is why paying extra early, or choosing a shorter term, saves so much interest. Educational tool, not financial advice.

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Data Inspector

Monthly payment$2,212

Total interest$446,406

Total paid$796,406

Governing equation

M = P \frac{i ( 1 + i ) ^{n}}{( 1 + i ) ^{n} - 1}, P = $350, 000, i = 0.00542, n = 360, M = $2, 212

Reading this result: At 6.50% APR over 30 years, the monthly payment is $2,212 and you pay $446,406 in interest — about 128% of the amount borrowed. The payment is level, but its split shifts: your first payment is mostly interest (86% of it), while the last is almost all principal. A higher rate or a longer term sharply raises the total interest, and paying extra early attacks principal before interest can accrue on it.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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Compound Interest

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Compound Interest & InvestingLive

the eighth wonder

Controls

Presets

Starting amount ($)

Monthly contribution ($)

Annual return

Years

Compounding means earning returns on your past returns, so growth accelerates over time. The gap between the balance line and your total contributions is pure compound interest — and it widens dramatically in the final years. Educational tool, not investment advice.

▶ Run in Python

Data Inspector

Final balance$691,150

Total contributed$190,000

Interest earned$501,150

Governing equation

A = 10, 000 (1 + \frac{0.070}{12})^{360} + 500 \cdot \frac{( 1 + \frac{0.070}{12} ) ^{360} - 1}{0.00583} = $691, 150

Reading this result: Rule of 72: at 7.0% a year, money roughly doubles every 10.3 years — about 2 doublings across your 30-year horizon. Each $500/mo contribution then earns returns on its own past returns, so the balance curve pulls away from your flat contribution line. Because compounding is exponential, most of the $501,150 in interest is created in the final years — time in the market matters far more than the amount. Educational tool, not investment advice.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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Frequently asked questions

Is this good for first responders?: Yes — this version of "Real-Estate Analyzer for a retirement fund" is framed for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.