About

How it works, what to watch and where the limits are.

This page explains the calculator methods, browser-only privacy model, local-data controls and the limits to keep in mind.

Version: 2026.07.29-014917Z

Methodology

Retirement simulator

The retirement page runs Monte Carlo simulations in your browser. It includes savings, random nominal returns, random inflation, spending tiers, mortgage payoff changes, Social Security timing and optional one-time payments.

It does not cover every tax rule, account type, healthcare expense pattern or policy change. The results are estimates based on what you enter.

Methodology

Lifestyle-cost planner

Lifestyle entries are annualized from amount, quantity and frequency. Buckets organize the cost of the life you want; they are not a judgment on the spending.

One-time items are kept visible because large occasional costs still matter for retirement planning, even when they are not part of a normal monthly budget.

Methodology

Budget and mortgage tools

The budget planner is manual entry. It separates must-pay expenses from flexible and discretionary categories, but it is not a tax engine or bank-sync product.

The mortgage calculator shows payment structure, payoff timing and housing costs for fixed, ARM-style and HELOC-style scenarios.

It is useful for planning, but it does not replace lender disclosures.

Methodology

Healthcare runway planner

The healthcare page compares pre-Medicare coverage costs using premium estimates, deductibles, out-of-pocket assumptions, HSA reserves and usage levels. It estimates costs; it does not recommend a plan.

It does not diagnose conditions, choose insurance products, guarantee premiums or cover every tax rule for HSA eligibility and reimbursements.

It also does not calculate official ACA subsidy eligibility or insurer-specific pricing. Treat these outputs as modeled ranges and compare them against real marketplace and plan quotes before making enrollment decisions.

Methodology

Output philosophy

Outputs are rounded on purpose. Ages, percentages and dollar amounts are kept readable because exact-looking numbers can imply more precision than the model has.

The goal is to show which inputs matter, which changes help and where the plan still looks weak.

Historical replay stays local-only, reuses the checked-in market dataset and remains a deterministic illustration distinct from the Monte Carlo probability outputs. It labels whether the path is historical-only or mixed once the data runs out.

Known limitations

What this model simplifies

Monte Carlo outcomes depend on your return, inflation, spending and timing assumptions. They do not model every market regime, policy change, tax rule or household event.

Tax, Social Security and healthcare outputs are planning estimates, not official benefit statements, subsidy determinations, underwriting decisions or final plan quotes.

Data stays local to this browser profile unless you export it yourself. If local storage is cleared or the device is lost, the app cannot recover your planning history.

Privacy

What stays local and what does not

Retirement inputs, lifestyle entries, budget values, mortgage scenarios, healthcare assumptions and shared profile defaults are stored in this browser using local storage and IndexedDB.

The app does not send calculator fields, scenario names, notes or output values to a server.

Historical replay stays local-only, reuses the checked-in market dataset and does not send replay inputs or results to a server.

Privacy

Why this matters

Planning is more useful when you can try uncomfortable numbers. Keeping the calculations local makes it easier to test larger cuts, delayed retirement, worse markets or expensive lifestyle ideas.

Portable summary

Copyable planning summary

This read-only summary is for financial planner review or further external analysis.

Language

Privacy and local-data controls

Loading local-data status...

Import replaces saved browser-local planner data with the file you choose. If local data already exists, the app asks for confirmation first. After a successful import, the page reloads immediately so every tool rehydrates from the imported values on this device only.

Disclaimer

What the app does

It estimates retirement funding, lifestyle cost, housing cost and budget changes based on the numbers you enter.

Disclaimer

What the app does not do

It does not recommend securities, guarantee outcomes, replace lender documents, predict taxes with full fidelity or tell you that a plan is safe.

Disclaimer

How to use it responsibly

Use the outputs as a planning aid. Verify important decisions with qualified professionals, especially when the stakes involve taxes, healthcare, legal obligations or large irreversible commitments.