i will respect the power of compound interest

[Hey guys! If you love numbers and forecasting and poking around new financial calculators, you’re going to enjoy this review of OnTrajectory today 🙂 It comes from Gwen of FieryMillennials.com and should give you something exciting to do over the weekend! Haha… Hope it helps!]


Hi my name is Gwen, and I have a confession.

I love spreadsheets.

Not like, oh yeah occasionally I play around in Excel making spreadsheets. No no.


Chances are high you feel the same way. Many drawn to the FIRE life want to optimize their lives to the fullest, and one of the best ways to do so is through spreadsheets.

Months of income neatly listed in columns. Years of expenses documented in different tabs. Beautiful graphs made from forecasting the FV formula.

I can’t. Get. Enough.

Eventually, though, if you’re anything like me, you run out of variables to change. The joy starts to fade from putzing around in Excel, and you need something more to keep up the high…

Enter, OnTrajectory.

ontrajectory logo

I’m pretty sure this beautiful piece of software is a love child from Excel having a one-night stand with the cFIREsim calculator.

OnTrajectory (or OT) bills themselves as “A Financial Planner and Analyzer – All in one easy-to-use graphically interactive program.” They’re not wrong. It’s beautiful.

You start off entering in some details about you: age, total savings, annual income, and how much income you save monthly. You can skip these questions and enter them manually if you want a more granular control over where that information goes.

After it processes the information, you’re taken to the main screen where you have a number of options.

Let’s start with income:

ontrajectory income screen

[click to enlarge]

The thing I love most about OT is the flexibility to include multiple streams of income that last as long as you want.

  • Day job income until you’re 34? Done.
  • Great Aunt Ethel passes away when you’re 50? Put that chunk of change in there.
  • Lucky enough to get a pension that starts at age 65? You guessed it: that can go in there as well!

Moving on to expenses:

ontrajectory expenses screen

[click to enlarge]

Much the same story as income, except these are all the things you’re spending money on.

  • Only paying for college for 2 years for the kiddo? You can include that.
  • Finish paying off the house at age 45? You get the picture.

I also like that you can go super granular and include your actual budget for expenses. It’s for those that really want to go deep into their budget and estimate how changing things like not spending money on work clothes and spending more money on vacations and tequila affects their timeline.

(I may or may not be one of those people.)

After expenses comes the really fun part: Accounts and Taxes

(Is that the first time anyone has ever said taxes are fun?)

ontrajectory accounts taxes-screen

[click to enlarge]

This is the section where you get to add in all of your existing accounts. If you’re like me, this could take awhile. It’s worth it, I promise.

Notice how in the picture above I have a 401k in there? Well, if you look closer at the numbers that I totally made up out of the blue, you’ll notice how it has two sections. The first section is the years I’m going to contribute money to it while I’m still working. The second part is the growth stage, where I don’t touch my beautiful little nest egg and let it grow untouched for 29 years.

As with all the other sections, you can change the date ranges and amounts contributed to see how it changes your trajectory. One really fun thing to do is to look at what your projected end number is if you stop contributing to you 401(k) this year. I bet the number is higher than you would think it would be! I wouldn’t recommend, however, seeing what your number would be if you worked for 35 years and contributed the max. Let’s just say I’d be worth well over 7 figures if I decided to sacrifice the best part of my life to ‘The Man’.

The next tab is “goals”

I’m going to be completely honest here and let you know I haven’t fiddled with this section too much. Simply because I’m a Type A person and I don’t like setting goals that are so dependent on something as flaky as the US Stock Market.

There are a number of goals you can set, though, like Trajectory reaches $ on this Date _____,  Projected Progress reaches $ on this Date ______, and Trajectory reaches $ on _____ at this cumulative RATE _____.

The last and final tab is simply a list of all the progress check-ins you’ve done so far.

Everything combines to make a chart that looks something like this:

ontrajectory end balance graph

[click to enlarge]

As you can see, this very simple example would have me living a life full of comfort and luxury until the end of my days. Yay!

I know this because not only does the graph end on a record high, there is also a handy dandy notification that says so. Not in those exact words though, sadly.

The notification area comes with a variety of different messages, from successful trajectory to early withdrawal penalties to projected shortfall warnings. Here are what some of them look like:

ontrajectory future notifications

At the risk of babbling on and on about this awesome website (seriously I could talk about it all day. I feel like I’ve barely scratched the surface!) I will end with a quick summary.

Pros of using OnTrajectory

  • Gives you robust projection capabilities that Excel can’t provide
  • Can get way down into the details
  • It’s very well documented
  • It looks great!
  • Their support responds promptly (now with a dedicated subreddit!)

Cons of using OnTrajectory

  • The free version only lets you put in a few accounts (which is fine to poke around, but to truly get a good idea you need to add all your different accounts which requires upgrading to the “PowerPlan” at $5.00/mo)
  • Takes a while to set up the first time


OnTrajectory really lets you dig into the nitty gritty details if you’re a numbers person. I’ve been using them for over a year now and I love it. I feel far more confident with my plans now that I can see the definite impact of working a few more years or not fully maxing out my 401(k).

Highly recommend checking them out! OnTrajectory.com


Gwen is the founder of fierymillennials.com, a blog about achieving financial independence from a millennial’s point of view. She’s on Twitter [@fierymillennial] and also has Instagram and Facebook.

FYI: This post includes affiliate links to OnTrajectory, but of course we only blog about products we love and use here regardless of compensation. If we think it’ll help you we’ll share it!

[Awesome pic up top of the founder of OnTrajectory, Tyson Koska ;)]