Have You Already Saved Enough for Coast FIRE?

You've been saving for years. You've got a decent chunk invested. But have you actually stopped to check — could you stop contributing today and still retire on schedule? For a lot of people, the honest answer is closer than they think, and for others, it's further away than the number in their head. Here's how to actually know which side you're on.

What Coast FIRE Actually Means

Coast FIRE is the point where you've invested enough that — without contributing another dollar — compound growth alone will carry your portfolio to a full retirement number by your target age. You don't stop working. You stop needing to save for retirement. From that point on, your paycheck only has to cover today's expenses; your existing investments handle the rest, growing quietly in the background whether you add to them or not.

The name is literal: once you've done the hard part — building that initial invested amount — you can "coast" the rest of the way, powered entirely by time and compounding rather than continued sacrifice.

Common Misconceptions

• "Coast FIRE means I can quit my job." Not quite — you still need income to cover today's living expenses. What you don't need anymore is income specifically earmarked for retirement savings.
• "If I've hit my number, I'm guaranteed to retire on time." The formula assumes a steady average return every year. Real markets don't move in a straight line — a bad decade early on could shift the timeline, even after reaching the number.
• "I have to hit this exact number or I've failed." Most people never formally calculate or hit a specific Coast FIRE number and still retire fine. It's a useful milestone and mental model — not a mandatory checkpoint with a pass/fail outcome.
• "This only applies to people trying to retire early." The underlying math — that time matters more than the amount you start with — applies whether you're aiming to retire at 45 or 67. Coast FIRE is just the clearest, most concrete version of that lesson.

How to Know If You've Already Reached It

The check is simple in concept: compare what you currently have invested against your Coast FIRE number (the formula below). If your current invested savings already meet or exceed that number, you've reached it — you could stop contributing entirely and, at your assumed rate of return, still hit your full retirement target by your chosen age.

If you're under that number, you haven't reached it yet — but that's the normal, expected state for most people at most points in their working life. It's not a failure, it's just information: you know how much more you need, and continuing to contribute monthly closes that gap faster than waiting it out passively.

Factors That Affect Your Number

Four inputs entirely determine your Coast FIRE number, and small changes in any of them shift it meaningfully:

• Years until retirement. The single biggest lever. More years left means compounding has more time to work, which lowers how much you need invested today.
• Expected annual return. A higher assumed return shrinks your Coast FIRE number — but assuming too high a rate (above 8-9%) risks an unrealistic plan. Most planners suggest 6-7% as a reasonable, inflation-adjusted long-term average.
• Annual expenses in retirement. This drives your full FIRE number (25× this figure), which in turn drives your Coast FIRE number. Lowering planned retirement spending — even modestly — lowers both numbers together.
• Whether you keep contributing. Coast FIRE describes the point where contributions become optional, not mandatory going forward. If you're not there yet, continuing to add monthly is what actually closes the gap.

Examples

Someone who is 35, plans to retire at 65, expects to spend $60,000 a year in retirement, and assumes a 7% return needs a full FIRE number of $1,500,000 (25 × $60,000). Working backward through 30 years of compounding at 7%, their Coast FIRE number comes out to roughly $197,000. Invest that amount today, add nothing further, and by historical average returns it grows to $1.5 million by 65 — entirely on its own.

Age at the time you start matters enormously for the same target:

*Based on a $1.5M retirement target (25 × $60,000 expenses) at a 7% annual return.

Notice what's happening: someone starting at 25 needs less than a quarter of what someone starting at 55 needs to reach the exact same retirement outcome. That's not because the 25-year-old is more disciplined — it's purely the mechanical effect of time on compound growth. This is the same principle behind CalcFactor's student compound interest lesson, just applied to real retirement numbers instead of a hypothetical.

Frequently Asked Questions

What is Coast FIRE?

Coast FIRE is the point where you've invested enough that, without contributing another dollar, compound growth alone will carry your portfolio to a full retirement number by your target age.

How is the Coast FIRE number calculated?

Coast FIRE Number = (Annual Retirement Expenses × 25) ÷ (1 + Expected Annual Return)^(Years Until Retirement).

Does Coast FIRE mean I can stop working?

No. It means you can stop saving for retirement specifically — you still need income to cover current living expenses.

What if I haven't reached my Coast FIRE number yet?

That's normal for most people. Continuing to contribute monthly gets you there faster; reaching it isn't required to retire eventually.