Coast FIRE is the first checkpoint in the FIRE speedrun that materially changes your options. Once you hit it, time is doing the compounding work for you — with or without your continued investment.

What is Coast FIRE?

You have reached Coast FIRE when your current investments will grow to your full FIRE number by traditional retirement age (typically 65) without any additional contributions, assuming a standard 7–8% annual return.

At this point, you only need to earn enough to cover current expenses. The future is locked in.

The Coast FIRE Formula

Coast FIRE Number = FI Number ÷ (1 + return rate)^years_to_retirement

Example:

  • Annual expenses: $50,000
  • FI Number: $1,250,000 (50K ÷ 0.04)
  • Current age: 32
  • Target traditional retirement: 65 (33 years away)
  • Assumed return: 7%

Coast FIRE Number = $1,250,000 ÷ (1.07)^33 = $140,000

At $140K invested at 32, you can coast to full FIRE by 65 without investing another dollar.

This is achievable in under 5 years for many people. It is not a fantasy number.

Step 1: Calculate Your Coast FIRE Number

You need three inputs:

  1. Your annual expenses (or target retirement expenses)
  2. Your current age and target traditional retirement age
  3. Your expected real return rate (7% is reasonable for diversified index portfolio)

Use our Coast FIRE calculator or the formula above.

Pro tip: Use your current expenses as the upper bound, but recognize that retirement spending patterns often differ from accumulation-phase spending.

Step 2: Understand What Changes at Coast FIRE

Once you hit your Coast FIRE number, the psychological and strategic landscape shifts dramatically.

You can:

  • Take a lower-paying job you find more meaningful
  • Start a business without income pressure
  • Go part-time, freelance, or contract
  • Take career risks that would be irresponsible otherwise
  • Slow down without guilt

You still need to:

  • Cover current expenses with earned income
  • Maintain investments without withdrawing early
  • Account for healthcare costs if employed part-time

This is why many FIRE-seekers identify Coast FIRE as the milestone that unlocks freedom of choice — even before full FIRE.

Step 3: The Barbell Strategy Post-Coast

Once Coast is hit, an effective strategy is the barbell approach:

One side: Continue your current career for 2–5 more years, maintaining strong savings rate. This compresses the time to full FIRE significantly.

Other side: Begin exploring and building what comes after. Start a side project, consult in your field, develop a new skill set, build a low-overhead business.

The psychological lift of having the future secured makes this exploration much more productive.

Step 4: Avoid the Trap of Inflating Post-Coast

The biggest risk at Coast FIRE is using the milestone as permission to increase expenses permanently. If lifestyle inflates to match the new, higher spending capacity — you push both your Coast and full FIRE numbers up simultaneously.

The discipline required: acknowledge the milestone, improve life in meaningful ways, but maintain or modestly improve the gap between income and expenses.

Step 5: Build Toward Lean FIRE Next

After Coast, the logical next milestone is Lean FIRE — the ability to retire on a lean budget.

Lean FIRE typically means:

  • Annual spending: $25,000–$40,000
  • FI Number: $625,000–$1,000,000
  • Geographic flexibility: often involves LCOL areas or geo-arbitrage

Many people find that Lean FIRE achieves what they actually want: exit from careers they dislike, freedom to choose work, location independence, and elimination of financial stress.

The full FIRE number (often based on higher spending) becomes optional — a stretch goal rather than the minimum required for freedom.

The Compounding Magic Behind Coast

Here's why Coast FIRE is so powerful:

At 25, you need $70,000 to hit Coast FIRE for a $50K/year retirement at 65 (40 years). At 30, you need $100,000. At 35, you need $143,000. At 40, you need $204,000.

Every year you delay, the required Coast number grows by 7%. Hitting it early and letting compound interest do the heavy lifting is the core insight.

The earlier you hit Coast, the longer the runway. A 25-year-old who hits Coast FIRE has 40 years of compounding ahead — potentially retiring with $2–4M without another dollar invested.

Run your numbers. Coast FIRE is closer than you think.