How Much Do You Really Need To Retire Early?

How much do you need to retire early is just a math problem. No secret formula. Definitely no social media guru hawking some overpriced “exclusive course.” It’s knowing exactly what you spend, for how long, and how much you need to cover it.
Once you strip away all the noise, it becomes pretty simple. I figured mine out without listening to “good advice,” and you can too.
In this article, we’ll break down exactly how to calculate how much you need to retire early. You’ll walk away understanding the math, the mindset, and the method to get there.
Ready to finally know your number? Keep reading.
Table of Contents
Why Listen to DadisFIRE?

I’m not just some random voice online throwing theories around. I’ve actually retired early. I figured out this FIRE math decades ago, applied it, and left the workforce in my early 40s. No handouts, no lucky breaks, just smart moves.
I am also a Chartered Financial Analyst with more than 20 years of experience in Financial Services.
So when I say it’s just a math problem, I mean it, I solved it.
Why “How Much You Need” Starts with Knowing Your Spending

You control your spending, both pre-retirement and in retirement. That’s the lever most people overlook. Your number depends entirely on what your lifestyle actually costs, not what you think it costs.
Here’s how to calculate your expenses. I will dive deeper on each of these further in the article:
What I recommend is
1) add up your total expenses over the last 24-36 months. Divide that by 24-36
2) Think about your purchases every 36-120 months (cars, houses, appliances, unexpected medical expenses, BIG vacations, etc). Divide that by 36-120.
3) multiply that previous number by the number of periods you think you’ll need it (e.g. If you divided by 120, then how many 10-year increments do you think youll need it)
4) Add a buffer depending on how conservative you are.
5) subtract out expenses that will fall off (like mortgages)…..you’ll need to do creative math for that.
6) project your healthcare expenses (just go to healthcare marketplace and simulate it as if you are signing up)
7) Make some assumption about inflation
Now let’s learn more about each of these.
Determine Your Average Monthly Spend

Pull up your real expenses for the last 24 to 36 months. Add them all up, divide by 24 or 36, and now you’ve got your true average monthly spending. Until you know that, everything else is just guesswork.
Your expenses set the baseline for how much you need to cover, so don’t skip this step.
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Don’t Forget the Big, Irregular Purchases

Here’s where most people blow it, they forget the big stuff. It’s easy to track rent and groceries, but what about those once-in-a-decade wallet punches? I’m talking about cars, houses, appliances, surprise medical bills, or that bucket list trip.
You need to look at your last 36 to 120 months and see where those heavy expenses hit. Divide that total by the number of months, then think about how many more decades you’ll want (or need) to cover similar big-ticket purchases.
This keeps your math honest. Don’t pretend big expenses won’t happen, they will.
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Subtract What Won’t Be There Forever

Now, let’s clean up the equation. Not every expense sticks around forever. That mortgage? Eventually paid off. Student loans? Gone. Even the daycare bill disappears when the kids grow up and move out.
You’ve got to take a hard look at your expenses and figure out what drops off in 5, 10, or 20 years. It’s not straightforward, this is where you need to get a little creative with the math.
But once you strip out those temporary expenses, you’ll have a clearer, more realistic picture of what your long-term spending actually looks like.
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Don’t Skip Healthcare Costs

One of the biggest blind spots people have when they map out early retirement is healthcare. It’s easy to ignore when an employer is footing the bill, but once you’re on your own, it’s an entirely different story.
You can’t just plug in some made-up number and hope for the best. Go straight to the Healthcare Marketplace, pretend you’re signing up today, and see exactly what those premiums, deductibles, and maximum out-of-pocket numbers look like.
Don’t stop at the premium, look at the full annual cost because one unexpected illness can wipe out the budget fast. Build those numbers into your plan early and adjust them for every stage of life. Ignoring healthcare is the fastest way to wreck your early retirement.
Inflation: The Quiet Killer of Early Retirement Plans

If you think today’s dollars will stretch the same way in 20 years, you’re already setting yourself up for failure. Inflation is the slow, sneaky drain no one talks enough about. It chips away at purchasing power little by little until suddenly, what used to cover your monthly groceries now barely fills half a cart.
Don’t use some outdated static number, factor in a reasonable inflation rate, usually around 2-3% annually. Over decades, that small percentage compounds into something massive.
Failing to account for inflation means you’ll wake up at 65 realizing your perfectly calculated nest egg won’t cut it. Inflation isn’t optional. It’s reality, so plan for it.
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Add a Buffer: Because Life Happens

Even the best spreadsheets can’t predict every curveball life throws at you. Things break. Emergencies show up uninvited. Maybe you’ll want to help out family or take that spur-of-the-moment trip.
That’s why you don’t just calculate what you think you’ll need, you tack on a solid buffer. Call it a safety net, call it peace of mind, but don’t skip it. Some people add 10%, some 20%, depending on how risk-averse they are.
You know yourself better than anyone, so adjust accordingly. The goal is simple: avoid running out of money because of something you didn’t see coming.
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Calculate: The Simplified Math

Now it’s time to tie all this together. Once you’ve got your true monthly expenses, including healthcare, inflation, big-ticket items, and your buffer, you’re ready to run the numbers.
Plug them into any Time Value of Money calculator. Set your retirement age, expected lifespan, rate of return, and those monthly expenses you calculated. The result? That’s your target lump sum.
Watch how quickly the math adjusts when you tweak spending or expected returns. It’s just plugging in real numbers and seeing the outcome.
This is the same equation every FIRE story out there is based on.
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Time Value of Money: The Formula You Actually Need To Retire Early

Let’s get this straight, every financial plan boils down to understanding the Time Value of Money. No need to overthink it. It’s just a way to figure out how today’s dollars grow (or shrink) over time.
There are five basic parts, and once you know them, you can solve for anything. First is Present Value. That’s how much money you have today, sitting in your accounts or investments.
Second is Future Value. That’s how much you want or need to have later, say, the size of your nest egg at retirement. Third is Interest Rate, or rate of return. It’s what you expect your money to earn each year (keep it realistic, like 5%).
Then there’s Payment. This is any money you’ll add or take out over time. Are you saving regularly, or withdrawing to fund your lifestyle? Finally, there’s Time. That’s how many years you’ve got before you’ll start needing the money, or how long you need it to last.
Know any four of these, and you can solve for the fifth. It’s that straightforward. Plug them into any calculator and you’ll see exactly where you stand.
Income Strategy: How You’ll Actually Fund Retirement

Having a big number is one thing. Figuring out how to turn that number into income is another. This is where strategy matters. Some rely on a steady withdrawal rate. Others build income through rental properties, dividends, side gigs, or a combination of all three.
Every FIRE Story Is the Same Math, Different Assumptions

It might look like everyone has a different secret, but they’re all working off the same framework. The only thing that changes is the inputs. Some people cut spending to the bone. Others build massive income streams. Some retire at 30, others at 50.
The math never changes. It’s just your preferences, lifestyle, and risk tolerance shaping the outcome. Once you understand that, you’ll stop wondering if there’s a magic formula. There isn’t.
It’s all about how you tweak your assumptions to fit the life you want.
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Bottom Line: You Control the Timeline

Here’s what all this boils down to, you’re in charge. You decide how much you spend, how much you save, how soon you want out. Every lever is yours to pull.
If you want to retire early, it’s not complicated. It’s just math and mindset. Get real about your expenses, run the numbers honestly, and adjust until the plan works for you. No more excuses, no more waiting for permission.
You’ve got the formula. Now use it.
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