Question 1

What is Coast FIRE?

Accepted Answer

Coast FIRE is the point at which your existing savings, left to compound with zero further contributions, will grow to your full FIRE number by your target retirement age. Once you reach Coast FIRE, you can 'coast' — only earning enough to cover your current living expenses, without needing to save anything for retirement.

Question 2

How is the Coast FIRE number calculated?

Accepted Answer

Coast FIRE number = FIRE number / (1 + annual return)^years to retirement. For example, if your FIRE number is £625,000, you expect 7% annual returns, and you have 30 years to retirement: £625,000 / (1.07)^30 = £82,100. If you already have £82,100 invested, compound growth alone will reach £625,000 in 30 years.

Question 3

What is the difference between FIRE and Coast FIRE?

Accepted Answer

Regular FIRE means you have enough to retire immediately — your portfolio can fund your expenses via withdrawals today. Coast FIRE means you have enough that compound growth will get you to FIRE by a future target date. You still need to work for living expenses, but you don't need to save for retirement. Coast FIRE is a milestone on the way to full FIRE.

Question 4

Is Coast FIRE realistic for UK investors?

Accepted Answer

Coast FIRE is achievable, but the calculation is sensitive to the assumed growth rate. At 7% nominal returns (roughly 4-5% real), it works well over long periods. The risk is that a poor decade of returns early on could derail the projection. UK investors should also consider that pension access is restricted until age 57 (rising to 58 in 2028), so Coast FIRE via a pension requires patience.

When can you stop saving?