# Coast FIRE calculator for iPhone

> A Coast FIRE calculator for iPhone: your coast number up front, a projection you can drag across, and a glossary. $0.99 on the App Store.

Source: https://mycoastfire.com/app

My Coast Fire Calculator puts your coast number on your home screen. Open it, move a slider, and you know in a second whether you can stop saving for retirement.

[![Download on the App Store](/app-store-badge.svg)](https://apps.apple.com/app/id6811446556?ct=web-landing-app&mt=8)

$0.99 · iPhone and iPad · iOS 17.6 or later

## What the app shows you

The big number at the top is your coast number: the amount you need invested today for growth alone to reach your retirement target. A ring next to it fills in as you get closer. While you're short, the app is red and tells you the age you'll get there at your current contribution. Once your savings cover it, the whole screen turns green. That color change is the point of the app, and it's a surprisingly good nudge.

The Projection tab charts your portfolio year by year to retirement against a dashed target line. Drag your finger across it to read the balance at any age. It also shows your projected balance at retirement and how far over or under your target you'll land. Like the [calculator on this site](https://mycoastfire.com/), it assumes you keep contributing until you reach your coast number and then stop.

The third tab is a short glossary: Coast FIRE, coast number, target, return rate and withdrawal rate, each explained in a sentence or two. Handy if you're showing the app to a partner who hasn't read about any of this.

## Should you use the app or the website?

The website is free and does more. Besides the [Coast FIRE calculator](https://mycoastfire.com/), it has versions for [Social Security and pensions](https://mycoastfire.com/coast-fire-calculator-with-social-security), [couples](https://mycoastfire.com/coast-fire-calculator-for-couples) and [market ups and downs](https://mycoastfire.com/coast-fire-monte-carlo-calculator), plus the [4% rule](https://mycoastfire.com/4-percent-rule-calculator) and [compound interest](https://mycoastfire.com/compound-interest-calculator) calculators and the guides that explain the math.

The app is for the quick check. You're deciding whether to take a lower-paying job, or you just got a raise, or the market dropped and you want to see where that leaves you. Two sliders and you have an answer, without typing a URL or finding a bookmark. If you only run the numbers once a year, the website is plenty. If you like to check in often, the app is worth the dollar.

## Is the math the same?

Yes. Your target is yearly spending divided by your withdrawal rate, so $60,000 at 4% is $1.5 million. Your coast number is the amount that grows into that target by your retirement age at your return rate. The [methodology page](https://mycoastfire.com/methodology) goes through every formula.

The only thing to watch is the return input. The app uses a real return, which is already adjusted for inflation, so everything stays in today's dollars. This site asks for the return and inflation separately and works out the real return for you. A 7% return with 3% inflation is a real return of about 3.9%, so enter that in the app if you want the two to match.

Like everything here, the app gives estimates, not advice. Returns won't arrive as a smooth average, which is why the [Monte Carlo calculator](https://mycoastfire.com/coast-fire-monte-carlo-calculator) exists.

My Coast Fire Calculator

$0.99 on the App Store. Made by LetUsBake, LLC, the team behind this site.

[View on the App Store](https://apps.apple.com/app/id6811446556?ct=web-landing-cta-app&mt=8)

## Questions people ask

### How much does the app cost?

It's $0.99 on the US App Store, paid once.

### Does it work on iPad?

Yes. It needs iOS 17.6 or later and runs on iPhone, iPad and iPod touch.

### Will I get the same answer as the website?

The math is the same: your FIRE number is spending divided by the withdrawal rate, and your coast number is that target discounted back to today at your return. The one difference is the return input. The app asks for a real return, already net of inflation, while the website asks for a return and an inflation rate separately. Enter 7% and 3% on the website and you'll match the app at about 3.9%.

### Is there an Android version?

The app is on the App Store only. On Android, this website works in any browser, and you can add it to your home screen from the browser menu.