The FIRE calculator app for iPhone

By Kevin Lan · Updated September 2026

A FIRE calculator app estimates your FIRE number — the amount you need invested to live off your portfolio — and projects the year you'll reach it, then keeps that date in view on your phone. Here's what separates a genuinely useful one from a countdown toy.

What a good FIRE calculator app does

• It computes your number from your own inputs. A useful app takes your age, investments, contributions, expenses, and expected return and returns your FIRE number and the year you reach it — not a generic chart.
• It uses real, after-inflation returns. Planning in today's dollars keeps a figure decades out meaningful. An app that only uses a nominal return overstates what your money will buy.
• It covers the FIRE variant you care about. Coast, Barista, Lean, Chubby, and Fat FIRE each change the target. The math is the same; the app should let you pick.
• It shows the math. You should be able to see the formula worked through with your numbers, not just a result you have to trust.
• It keeps the date in front of you. A home-screen widget that counts down to your computed date — and updates as your net worth grows — is what turns a one-time calculation into something you use.
• It respects your privacy. Financial inputs are sensitive. Look for on-device storage, no account, no analytics, and a clear App Store privacy label.
• It doesn't lock the basics behind a subscription. This category resents subscriptions on what reads as a calculator. Free-to-calculate with an optional one-time upgrade is the friendlier model.

Web calculator or app — which do you need?

For a one-time answer, a web calculator like the one below is enough — it finds your number and date in seconds with nothing to install. An app earns its place when you want that date to stay in view and move as your net worth changes, or when you want deeper tools: a Monte Carlo success check, side-by-side scenarios, or Social Security and pension planning. Not everyone needs the app; the ones who do tend to be the ones who want to watch the number every week.

How FIRE: Retirement Calculator approaches it

Measured against the points above: it computes your FIRE number and date from your own inputs, uses a real (after-inflation) return by default, includes every FIRE variant, and shows the formula worked through with your figures. The home-screen widget counts down to the date it computes and moves as you update your net worth. Your data stays on your device — no account, no analytics, App Store privacy label Data Not Collected — and it's free to find your number, with an optional one-time Pro unlock and no subscription.

Frequently asked questions

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