Want To Reach FI Sooner? Join more than 18,000 others and get new tips and strategies from Can I Retire Yet? every week. Subscription is free. Unsubscribe anytime:

If you’re an Android user, please take a minute to download our new Free retirement calculator from the Google Play Store. This simple, easy app gives you a quick snapshot of your retirement situation. You’ll get answers in minutes.

Or, if you’d like a full-blown financial planner in the palm of our hand, try out our high-fidelity Pro version with asset allocation, multiple account types, financial events, detailed tax calculations, and many other features.

February update: Our version 1 development cycle is complete. New in the latest Pro calculator is full support for the Tax Cuts and Jobs Act of 2017. Plus, you can calculate your retirement plan with either the old or new tax law! We are seeing differences in ending net worth from 7% to 93%. How does your retirement plan fare under the new law?

Also recently added to the Pro calculator are Floor/Ceiling for cash accounts, Tax Basis for taxable accounts, State/Local taxes, and Property Current Value. Lastly, there have been a number of minor fixes. If you aren’t running the latest version, update now for free. If you have an Android device and still don’t own a high-fidelity retirement calculator, get Can I Retire Yet? – Pro !

These new retirement calculator apps are the result of many man-months of effort here at Can I Retire Yet? By downloading and reviewing either, or both, you’ll help us to jump start the products and spread the word. Thanks!

And if you’re interested in going behind the scenes of how and why these products were developed, read on below. You’ll learn about the design decisions and personalities involved, and you’ll get some helpful tips for analyzing your own retirement finances, whenever and however you do it…

From Adversity to Opportunity

Last winter I began a blog post like this: “It was a blustery winter day, just about a year ago, when I stayed indoors all afternoon to work at my desk. The snowflakes stacked on the railing outside as I broke ground on new software, something I hadn’t done in years. It would be a modeling framework that I could use for original research to analyze various retirement questions such as the best retirement withdrawal strategies and uncertainty in retirement calculations.”

But there is more to the story than that. I was at my desk that day, and almost every day for most of the next four months, due to a debilitating injury that left me unable to walk normally for more than a year.

I had time on my hands and couldn’t get outdoors as much as usual. To keep my sanity, what was I going to do with myself? A challenging intellectual project would be ideal. Maybe a software project. How about a retirement calculator?

Now, I’ve never put much faith in the absolute numeric results of retirement calculators. Once you understand the assumptions required, you realize you can’t take their predictions for your bank account 30 years hence as gospel. But they are good tools for comparing the relative value of your retirement options. Retirement calculators are simply the best way to get a feel for your retirement finances. And that’s far more important in reality than trying to find your ONE number.

That winter I had begun a series of articles on this blog featuring original personal finance research. Though I could accomplish a lot in Excel spreadsheets, I wanted the power and flexibility of a full-blown software environment like I used in my engineering career, to efficiently test investing and financial strategies. And, if I took that route, I might eventually wind up with a product that I could put into readers’ hands….

Still, it wasn’t a snap decision. Though I had a blog known for its reviews of nearly 100 retirement calculators, and though I was a software engineer by profession, I had long hesitated to create my own retirement calculator:

For one thing, I knew that developing software was a mammoth effort requiring domain knowledge, programming skills, graphical design, usability expertise, testing, marketing, and distribution. Where would I find the resources, working part-time in retirement, to check all those boxes and deliver a worthy product?

Secondly, there were already so many competitive products available. As my calculator reviews show, there are excellent choices for retirement calculators on the web, on the desktop, on Windows and on Apple mobile devices. In fact, just about every platform is covered with a highly competitive and worthy entry, save one….

Smartphones and the World’s Most Popular Operating System

Being the frugal sort, I had been late to adopt a smartphone. But once I got used to having a powerful computer in my pocket, I became a firm believer. No, I don’t walk around town with my eyes glued to Facebook or Twitter, but I am accustomed now to having full access to my files, the Internet, and powerful software apps, whenever I need them.

Coming from an engineering background, I respected Apple’s products, and was happy that they made life easier for so many people (including my wife). But engineers didn’t used to work on Apple. So, when it came time to buy a smartphone, I went straight to Android.

Being a personal finance blogger, I spent some time looking for a decent retirement calculator on Google Play. But I found nothing with reasonable modeling power, a modern user interface, and a critical mass of users. Given that Android is now the most popular operating system in the world, with more than 2 billion users, I saw both a genuine need and a business opportunity.

That frugal Android phones were also a favorite of the Financial Independence/Retire Early (FIRE) crowd was another attraction. Mr. Money Mustache and Jim Collins had written about low-cost Android phones for years. And Mr. Money Mustache has just announced his own Android app for accessing the popular blog.

So, that winter two years ago, I launched into designing and implementing a tool for advanced personal financial modeling in Java, using Android Studio. My goal, at first, was to create a flexible framework that I could use to test and validate both my own retirement theories, and the output from other financial tools. Eventually the framework would incorporate most of what I had learned about retirement planning and calculators over the past decade.

(I realize that many readers are dedicated Apple users. But we just didn’t have the resources to develop for both platforms initially. If the demand is there, we certainly will try to support iOS in the long run….)

Testing and Verification

As I developed and exercised my computer code, I first computed the expected answers by other means, and then verified the results produced by my framework. Today I have more than 150 automated test cases running. For simple cases, I computed the answers by hand. But for more complex cases I relied on other proven tools. The most important were TurboTax, for the U.S. tax code, and Pralana Gold for complex retirement scenarios.

Pralana Gold was created by Stuart Matthews at Pralana Consulting. The calculator has consistently ranked at the top in my reviews, and it’s safe to say that my project would not have succeeded without Stuart’s generous help. In a number of instances, he pointed me in the right direction for tricky retirement or tax modeling questions. His knowledge of financial planning and the U.S. tax code as it relates to retirement is second to none, plus he is an exceptionally talented software engineer.

Stuart and I developed an interchange format for retirement scenarios. This allows us to automatically transmit data back and forth and confirm the results in our respective models. To my knowledge, no other such “universal language” for retirement modeling exists. At one point, we even considered publishing or licensing this format for use in standardizing retirement calculators, but then we decided that felt too much like “work.” After all, we’re both supposed to be retired!

Ultimately we created five complex retirement scenarios covering a wide variety of initial conditions and retirement outcomes. In four of the cases our calculated results are within 1% of each other, and in the final case they are within 3%. If you know anything about accuracy in retirement modeling — where different retirement calculators can easily produce results varying by 100%, then you’ll appreciate the remarkable precision of those results produced by two completely different software developers and technologies.

Bottom line: we are very confident in our calculated results. And I am very proud of the Can I Retire Yet? framework. You won’t find better retirement calculators on Android.

But nothing has changed my view that if you want the very best and most powerful retirement modeling solution on the planet today, you owe it to yourself to check out Stuart’s offering — Pralana Gold, running on your desktop computer.

Choosing Feature Sets

Next I began to think about how to put my work in the hands of users. That meant marrying technical features to a user interface, and understanding what people at different levels of the financial planning process most needed….

I already had the data to answer those questions in my comprehensive retirement calculator reviews. So I re-viewed the reviews, creating a spreadsheet cataloging every possible retirement modeling feature — from input data to graphical output, from asset allocation to tax calculations.

Next I identified a subset of those features that would be reasonable to give away for free, and another subset that we could still realistically deliver on a mobile device, but would need to charge for. Ultimately those decisions crystallized into two products: Can I Retire Yet? Free and Pro.

Our Free version is a fun, interactive tool that lets you compute key retirement numbers in minutes, using just the essential input variables. The trick with Free was to collect just the most important data to rough out a retirement analysis, without overwhelming users. And I think we’ve accomplished that.

For users who need more accuracy, our inexpensive Pro version offers much more power including spousal input, multiple account types, custom asset classes, unlimited financial events, and detailed federal tax calculations including RMDs. Pro also has output reports, including tabular, graphical, and transactional views of your cash flow, which can be emailed to your desktop for further analysis.

If you just want a quick answer, Free is your best bet. But, if you really want to tinker with your numbers, Pro has the advanced features you need.

Designing and Delivering the Products

So, I had a plan for two products. Trouble was, I didn’t have the time, or the skills, to make them happen on my own.

During a drive through the southwest, I sat down for a day with my former colleague David, one of the most talented engineers I know, who had embarked on a new phase in his career. David now runs Ekorau LLC, a software and hardware development shop working in mobile, web and IoT (Internet of Things). Would he be interested in developing the user interfaces for the products I had designed, and then handling the marketing, distribution, and support?

We laid a piece of paper on his desk, and sketched some ideas to visualize the products. Though the math was tricky, Free would allow users to solve for different variables, such as “Age when I can retire” or “Annual income I need to retire.” The input would be done via sets of intuitive slider controls. And the output would be a simple fuel gauge, always visible, that would update in real time as users manipulated the controls. Simple, responsive, intuitive.

The Pro version would be somewhat more technical, and quite a bit more powerful. But the fundamental user interface structure would still be very simple: lists of People, Asset Classes, Accounts, and Financial Events. Later, we would add a FIND bar to allow quick calculation and navigation through the app. Three types of reports would provide output.

The work began in June 2016. Between us, David and I have 50+ years of software experience. But, as is often the case in software development, the process was far longer and more difficult than either of us envisioned. The Android architecture is sometimes buggy, inconsistent, and needlessly complex. But we persevered, and here we are today, with useful products finally “live” on the Google Play Store.

The “Perfect” Retirement Calculators?

In the early days of this blog, I wrote an article titled The “Perfect” Retirement Calculator, listing the features I thought were necessary for a state-of-the-art retirement calculator.

So, how close did we come in the new apps? Are these the perfect retirement calculators?

Well, these are real-world products created by human beings working part-time with finite resources. So, no, they aren’t perfect. But, they’re pretty darn good, especially when you consider they can perform sophisticated retirement modeling on a tablet or in the palm of your hand….

Let’s review some of the features from that early article and how we stack up now:

• Small amount of key data: Yes, the Free calculator in particular reflects a great deal of attention to collecting only your most essential input data (less than two dozen variables), and giving you an answer instantly.
• Flexibility with inflation rate and Social Security payments: Yes, both calculators let you set a global inflation rate, and choose the start date for all incoming payments. The Pro version lets you set event-specific inflation rates as well.
• Post-retirement income: Yes, both calculators allow specifying part-time work and other income sources after retirement.
• Flexibility in your spending: Though we haven’t implemented any sophisticated spending policies (yet), the Free version allows setting both pre- and post-retirement spending. And Pro allows an infinite variety and level of withdrawal events throughout the simulation.
• Modern user interface widgets: Yes, the Free version offers easy, friendly “sliders” for all numeric input. Touch a slider, move it to a new location, and watch the fuel gauge update in real time!
• Average return, historical, and Monte Carlo modeling: Both calculators currently offer average return calculations. Internally, we can do historical modeling, but you can’t get to it yet through the user interface. Monte Carlo is on the drawing board. Whether these features make it into the calculators depends on our user base. Honestly, I’ve grown to prefer average return analysis for most retirement simulations, as long as you understand the limitations. As discussed in my second book, I’m more interested in “driving” my retirement as it unfolds, then in computing some theoretical number that is allegedly safe in all possible future scenarios.
• Generating and comparing multiple scenarios: We don’t do this yet. We have the mechanisms in place to offer this feature, but if and when it will appear depends on user demand.
• Tabular and graphical output: Yes, Pro offers both of these. We are constrained by screen size on our target mobile devices, but the apps are quite usable all the same. And you can easily email reports to yourself, if you want to analyze them further on a desktop computer.
• Restatement of input data and key modeling assumptions: Yes, Pro includes a transaction log report that documents all program inputs, intermediate cash flows, and important annual statistics like tax rates, asset allocations, and account balances.
• Simple fuel gauge metaphor that shows how long your money will last: Yes, Free was built around this metaphor from the start. Try it out to see what you think…
• A final essential feature that I’ve written about more recently is detailed federal tax calculations: These are essential for accurate tax planning, especially later in retirement when RMDs come into play. Such tax calculations are brutal to implement accurately — requiring both accounting and software expertise, but Pro has them.

Your Last Chance to Be First

If this blog has helped you and you’re an Android user, please take a minute now to download our Free app from the Google Play Store. It’s a fun, simple way to get quick answers to your retirement questions. If you’re feeling more ambitious, you can try the Pro version.

And, if you’d rather see either of the products in action first, you can view a number of tutorial videos on our YouTube channel.

Once you’ve downloaded and tried either product, we’d love to hear your feedback — what worked for you, and what additional features you’d like to see in the future. I won’t be doing technical support directly via this blog or email, but you can leave reviews on the Play Store pages and correspond with us on the Ekorau forums.

By downloading and reviewing either the Free app or the Pro app, you’ll be helping us to spread the word and put effective, do-it-yourself retirement tools into the hands of others who can benefit. And, you’ll be getting a better handle on your own retirement plan!

* * *

Note: For many years, Pralana Consulting and Can I Retire Yet? were engaged in an informal technical collaboration aimed at raising standards for accuracy in retirement modeling, with no business relationship. However, as of January 2020 we have an affiliate relationship. That means, if you purchase a Pralana product here, a portion of the sale goes to support this site.

* * *