Planning Tools vs 4% rule

Rob Berger is a personal finance content creator I have a lot of respect for. I like how he explains things in understandable terms, etc. I subscribe and read his newsletter every week. YouTube: https://www.youtube.com/@rob_berger

FYI for those that might be interested: 8/25/2026 he is going to host a live show to walk through building a complete retirement plan in ProjectionLab.

can anyone recommend a good app to calculate retirement taking I to account social security & 401k (one spouse) and public employee pension (other spouse)

I agree. The 4% rule just a starting point, but it's not a retirement strategy.

One thing I'd add is that a retirement plan also needs to answer how your portfolio adapts when markets change. I've been using a calculator that has real, after inflation, returns for added safety.

Also a fixed withdrawal rate assumes the portfolio can absorb whatever sequence of returns shows up. In reality, the order of returns often matters more than the long-term average.

For me, the plan should cover three questions:

• How much can I safely spend?
• Where does the income come from?
• What changes if market conditions deteriorate?

The spending plan, tax strategy, and withdrawal order are all important, but so is having a process for managing risk instead of hoping the market cooperates. A If –> then plan if you know what I mean.

The best retirement plans aren't static—they evolve as your life and the markets do.

The 4% rule is very good as a general guideline. When you have 25X your desired spending then you can dig much deeper using all of the other tools that everyone has mentioned. The SWR Series is the gold standard when it comes to this stuff. Go read up on that

IMHO, the 4% rule is not a plan; at least not a very good one. It is a rule of thumb that is helpful as a target used for early planning.

A good retirement plan involves a retirement budget that includes hopes and dreams and a plan for a retirement lifestyle. As well as how to make that happen. A plan includudes what is needed for a base great life as well as the extra "would like to do/have" things.

A plan often has instructions for dealing varying expenses and income

• Social Security starts x number of years in,
• a mortgage stops in year x,
• Stop paying bills for the children in year x
• we want to spend an additional $xK per year during years x-x,
• an inheritance is expected around year x, etc
• What can/do we cut during lean years to save principle

It has an order in which accounts will be used

• up to the standard deduction from account x, the rest from account y until it is depleted, then account z.
• It also might include how to handle market downturns - during down markets take from bond funds or cash, if applicable
• how to fund the withdrawals/distributions - sell funds annually or monthly or use dividends

In the early years, you really only need a target. That is where the 4% rule is handy. Five years or less out, you need a plan. The Retirement Budget Calculator was a good tool. Sadly, it is no longer publicly available. Boldin, (used to be New Retirement) is a great place to start.

Your plan will change. My wife and I have been retired three (2023) and six (2019) years. We are now 61 and 63. Our spending is much different than we had planned. The market has done better than expected. We enjoy some of the nicer things now. In our working years, we never made more than $80K combined and much of that was put in retirement accounts and paying off the house. Now we spend a good deal less than $50K per year and travel domestically and internationally several times per year. We have also taken care of some home maintenance - new HVAC unit, painting, new carpet in the bedrooms, new stone shower in the master bath.

You should get similar results if you are using your tools properly. The problem is that most people who use tools and most CFPS do NOT use these tools properly and instead of using Base Rates for their assumptions, use overly conservative or aggressive assumptions.

Thus, the outputs most people are generating out of these tools are just garbage in, garbage out. There are objectively right ways to do forecasting and wrong ways, and most people are doing it the wrong ways because they never learned the correct ways and these calculators encourage misuse and bad forecasting (especially Boldin).

Here is a good article exemplifying this problem:

The Crushing Cost of Conservative Retirement Planning - The Best Interest

If you're not careful, conservative assumptions could lead you to work for decades longer than you need to.

The Best Interest

You are correct that most retirement planning tools take more into account than any Safe Withdrawal Rate (SWR) target (4% rule of thumb or otherwise). Think of SWR as a directional target - not a precise retirement readiness trigger. You should definitely use retirement planning tools (preferably more than one) and/or a fee only fiduciary financial advisor familiar with FIRE to double check any plan before you actually commit to a specific retirement timeline.

A couple reasons that the 4% rule of thumb will often be more optimistic than planning software is:

1. most SWRs are based on historical worst case actual return sequences, whereas planning software typically uses Monte Carlo simulation. Since "past performance is no guarantee of future results", Monte Carlo is somewhat more representative of the potential future risk of a poor sequence of returns, though it is somewhat overly pessimistic in that it can generate some crazy sequences that would never actually happen. Real risk is likely somewhere between worst case historic and Monte Carlo simulated probability, though likely closer to Monte Carlo.
2. 4% "rule" [of thumb] research result is based on 30 year planning horizon (at least with a simple stock/bond portfolio) and probability of success with 4% drops with longer FIRE durations (see part 1 of EarlyRetirementNow Safe Withdrawal Rate series, "Success Rates for different SWRs, by equity share and retirement horizon (1871-2015)" table for detailed success probabilities of extending 4% to 40-60 years).

As others already said, 4% is a guide and even that it’s out of date and overly conservative.

Yes use planning software but not just one. To Matt’s point, inputs and assumptions matter a lot and they all treat things differently. I’m doing a full analysis write up of the top tools but the key takeaway would be leverage something like portfolio visualizer financial tools to test high level strategy of your drawdown portfolio and expenses. (Leverage portfolio charts and testfol.io to help determine what portfolio you want).

then boldin / projectionlab are good for details like conversions and taxes but tend to skew projections as they look at only equity and bond and straight rates (not true historical ups and downs; which again is where assumptions play a major role).

so yes use them, and use may of them, but again just further information not a set answer.

My estimated retirement date is at LEAST 10 years out. For me, a variance of 2-3 years doesn't matter yet. I'll seek more precision as I get closer to the target.

I wish folk would stop saying 4% "rule", when it's really "4% Safe Withdrawal Rate (SWR)", based on a 2-fund portfolio.

4% (x25) is plenty "good enough" directional accuracy when you're starting. Reality says you don't really have a clear understanding of what you'll want a decade or more later. As you go, you refine the plan and retirement expenses. You learn that when you're within10 years from target (over 50% to FI) you might know more about yourself and goals, and you'll learn that there's vastly better Retirement Phase portfolios than piddly 4% SWR. As you start transitioning into the higher SWR portfolio, like Golden Ratio, it's more like 5% (x20) and probability of hitting FI on estimated timeline improves.

Sure, projection software improves some aspects of planning, like how much you'll need, when, but planning software is only as good as the inputs and assumptions. Over long horizons, small inaccuracies compound error, so not hugely worthwhile. I'd absolutely recommended anyone approaching retirement hire an independent, fiduciary, advice-only CFP who uses software like RightCapital to validate the plan and check for blind spots. But that's much closer to actual retirement, when there's much more clarity in the plan and a bit more accuracy to near-term goals and expenses.

I retired about 6 years ago, at 45. Even in retirement there's changes of plans/ goals, etc. It's worth more understanding the boundaries and knowing how to freely maneuver within them.

A lot of that hinges upon what your plan is for "early retirement" (or the next chapter in your life). Last year Doc G wrote a piece titled *Retire at 80%*. He makes the argument that most people don't need to wait to be 100% there. It is worth considering your future plans and thinking about whether you will end up with unexpected income (the most common thing that would indicate retiring at 80% is workable). It's also worth considering whether a particularly high degree of precision is needed, since we rarely find ourselves traveling along the precise path we envisioned.