What Is Coast FIRE?

Coast FIRE is the point where you have saved enough that even with zero additional contributions, your portfolio will grow to support your retirement spending at your target age. The "number" depends on three variables: years to retirement, expected real returns, and desired spending level at retirement.

The formula is straightforward. First, determine how much you need at retirement by dividing your desired annual spending by your safe withdrawal rate. If you want $50,000 per year and use a 3.5% SWR, you need $1,428,571 at retirement. Then discount that amount back to today using your expected real return rate. If you are 32 with 33 years to retirement at 6% real returns: $1,428,571 / 1.06^33 = $209,368. That is your Coast FIRE number.

A concrete example makes this tangible. A 32-year-old with $300,000 saved, targeting retirement at 65, expecting 6% real returns. The math: $300,000 × 1.06^33 = $2,044,694 at retirement. At a 3.5% SWR, that portfolio supports $71,564 per year — well above the $50,000 target. This person has already crossed Coast FIRE. They could stop saving entirely, work any job that covers current living expenses, and still retire comfortably at 65.

The appeal is obvious: once you hit Coast FIRE, your relationship with work changes fundamentally. You can take a lower-paying job you enjoy, go part-time, start a business with no revenue pressure, or take a gap year. The compounding does the heavy lifting from here.

Why Fixed-Rate Coast FIRE Calculators Are Wrong

Every Coast FIRE calculator you find on a personal finance blog uses the same approach: pick a fixed annual return (usually 7%), compound it forward, and declare a number. The problem is that markets do not deliver 7% every year. They deliver −37% one year, +26% the next, then a lost decade that returns roughly 0% real.

The S&P 500 from 2000 to 2010 returned approximately 0% in real terms. A person who hit "Coast FIRE" in 1999 using a 7% fixed-rate calculator would have been told their $300,000 would grow to $590,000 by 2010. In reality, it barely held its inflation-adjusted value. That is not a tail risk — it happened within the living memory of most current investors.

The issue is sequence of returns risk. Even if the average return over 30 years is 7%, the order in which those returns arrive matters enormously when you are relying on compounding with no contributions. A lost decade early in your Coast FIRE period is catastrophic because there is no dollar-cost averaging to buy the dip. Your capital just sits there, shrinking in real terms, while the compounding clock ticks.

Monte Carlo simulation addresses this by running hundreds or thousands of randomized return sequences. Instead of one deterministic path, you get a probability distribution. You might find that your Coast FIRE number gives you 95% confidence — or you might find it gives you only 72%, meaning roughly 1 in 4 scenarios end in failure. That distinction is invisible to a fixed-rate calculator.

QuantCalc uses stochastic returns with regime-switching to model both normal markets and prolonged drawdowns. The result is a confidence level, not a false certainty.

Coast FIRE Numbers by Age and Spending Level

The table below shows how much you need saved today to be Coast FIRE, assuming retirement at 65, 5% real returns, and a 3.5% safe withdrawal rate. These are deterministic values — the Monte Carlo calculator above will show you the probability-adjusted reality.

How to read this table: A 35-year-old who wants to spend $60,000 per year in retirement needs approximately $397,000 saved today to be Coast FIRE. If they have more than that, they can stop saving. If they have less, they need to keep contributing until they cross the threshold.

Notice how the numbers rise sharply with age. A 25-year-old needs only $162K for $40K/yr spending because they have 40 years of compounding. A 45-year-old needs $431K for the same spending level with only 20 years of runway. Time in market is the single largest variable in Coast FIRE.

Coast FIRE vs. Other FIRE Variants

The FIRE movement has splintered into several sub-strategies. Each represents a different tradeoff between savings rate, work duration, and lifestyle flexibility.

Coast FIRE is unique because it is the only variant where you are not yet financially independent. You still need income to cover current living expenses. What you have achieved is freedom from the obligation to save. This makes it the earliest FIRE milestone most people can reach — often in their early-to-mid 30s on a median income — and the one with the most lifestyle impact per dollar saved.

Barista FIRE is closely related. The distinction: in Coast FIRE, you work to cover current expenses only. In Barista FIRE, you work part-time and the income covers both current expenses and continued savings. Many people use Barista FIRE as a bridge from Coast FIRE to full financial independence, especially when they want employer-provided health insurance. See the semi-retirement calculator for modeling how part-time income interacts with ACA subsidies and taxes.

Frequently Asked Questions

What is Coast FIRE?

Coast FIRE is the financial independence milestone where your existing savings, growing at expected market returns, will be sufficient to fund your retirement at a target age without any additional contributions. You still work to cover current expenses, but you no longer need to save. The term "coast" reflects the idea that you can coast through the remaining working years without the pressure of aggressive saving.

How do I calculate my Coast FIRE number?

Divide your target retirement spending by your safe withdrawal rate to get the portfolio needed at retirement. Then discount that back to your current age using expected real returns. The formula: Coast FIRE Number = (Annual Spending / SWR) / (1 + Real Return)^(Years to Retirement). For example, $50,000 spending at 3.5% SWR needs $1,428,571 at retirement. Discounted back 30 years at 5% real: $1,428,571 / 1.05^30 = $330,476.

Is $500,000 enough for Coast FIRE at 35?

At 35 with a 65 retirement target, 5% real returns, and 3.5% SWR: you need $50K spending / 0.035 = $1.43M at 65. Discounted back 30 years at 5%: $1.43M / 1.05^30 = $331K. So $500K at 35 already exceeds Coast FIRE for $50K/year spending by a wide margin. However, Monte Carlo simulation shows only about 85% confidence due to sequence-of-returns risk. A lost decade early in the 30-year period can derail the compounding. That is why running probabilistic scenarios matters more than the deterministic answer.

What return rate should I assume for Coast FIRE?

Conservative estimates use 5% real (after inflation) for a diversified portfolio. This roughly matches the long-term US equity premium minus a margin of safety. Using 7% nominal with 2.5% inflation gives similar results but obscures inflation risk. More aggressive assumptions (6–7% real) are sometimes used for all-equity portfolios but carry higher volatility. QuantCalc uses stochastic returns with regime-switching to avoid relying on any single assumption — you see the probability distribution, not one number.

What is the difference between Coast FIRE and Barista FIRE?

Coast FIRE means your savings will grow to cover retirement on their own; you work any job to cover current living expenses. Barista FIRE means you work part-time to cover both current expenses AND continue some savings. The key difference: Coast FIRE requires zero additional savings, Barista FIRE supplements both spending and savings. Barista FIRE is often chosen specifically for employer health benefits — working enough hours at a company like Starbucks to qualify for health insurance while semi-retired.