Who Built This, and Why

I built this because I needed it.

Why this exists

Most retirement calculators are either too simple or too complicated. The free ones miss the math that actually matters — Social Security filing strategy, spouse coordination, tax drag, sequence-of-returns risk. The professional software gets it right, but it's slow, expensive, behind a login, and built for advisors managing client portfolios — not someone who just wants to run a few scenarios on a Sunday afternoon.

So I built something in between. It's free to use. Navigator, which adds the AI Advisor and the deeper planning tools, is $79, once.

Every assumption in this tool is documented in the methodology — formulas, source data, tax brackets, Monte Carlo distribution. Nothing is hidden.

Who built it

My name is Luke Newton. I have a software and financial services background, and I've spent enough time around retirement planning to know what good math looks like — and what shortcuts to avoid. I'm not a financial company, a fintech startup, or a registered investment advisor. I'm someone who spent time and money solving a problem I had, and figured others might find it useful too. This is a tool I'd want to exist — so I built it.

You can find me on Reddit as u/lnewton_me, where I'm active in r/DIYRetirement, r/Fire, r/ChubbyFIRE, and a few other personal-finance communities. If you've got a question and would rather ask it publicly, that's a good place to flag me.

How the math stays honest

A solo-built financial tool earns trust differently than a company does: by showing its work. Every formula the engine uses is published. The simulation is seeded, so identical inputs always produce identical outputs — which makes the whole engine testable. Before any release, an automated 32-gate verification pipeline re-runs 55 benchmark retirement scenarios and fails the release on a single dollar of unexplained drift. The full regime — what's tested, what's not, and every fidelity change with dates — is public in the trust framework.

Keeping up with the rules is part of that. Contribution limits, tax brackets, Social Security and Medicare figures change every year, and a one-person tool has to prove it keeps up, not promise to. A script reads the IRS, Social Security, Medicare and HHS publications every week; each new figure is tested before it goes into the engine; and a release can’t go out while a data set is overdue. Each year’s changes are listed on What changed this year, and the whole process is in the trust framework.

How the pricing works

The app and everything it produces — your projections, your scenarios, your Social Security analysis — is free. Navigator — $79, once — adds the AI Advisor reading your plan (25 deep analyses and 50 conversations), Smart Moves, Deep Search, saved scenarios compared side by side, the AI Plan Score and the PDF report. (If you run out, Advisor Plus is $29 and adds 10 more deep analyses plus 25 more conversations; Advisor 365 at $79 for 365 days unlocks unrestricted AI access for the year, though most never need that.) The AI costs real money to run, so I charge for it. No required subscription.

I'd genuinely rather more people use this for free than pay me. If it helps someone retire smarter, that's the point. The money keeps the lights on.

On your data

There's no account, no server storing your numbers, no database holding your plan — it lives in your browser. Two things can send your numbers out, and only if you choose them: the AI Advisor, which sends anonymized numbers to generate your reply and then discards them, and Share links, which put your numbers into the link itself (a shortened link passes through our server to our link-shortening service, which keeps the full link so the short one works). Otherwise nothing you enter reaches me — I don't even require an account.

The export is designed to be useful on its own — or as preparation for a conversation with a financial advisor.

Get in touch

Questions, bug reports, feature requests, or just telling me how your plan looks — all welcome. Use the contact form at the bottom of the homepage. I read every message and reply to most.