Coast FIRE Calculator

Use this calculator to estimate the amount needed today to coast to financial independence by retirement age.

What this calculator does

The Coast FIRE calculator finds the present amount that could grow into your FIRE number by retirement age without further contributions. It helps show whether existing savings can do the heavy lifting.

It uses:

• current age
• retirement age
• annual retirement expenses
• expected annual return

Coast FIRE Formula

Coast FIRE = FIRE Number ÷ (1 + r)^n

Where:

• FIRE Number = annual expenses ÷ withdrawal rate
• r = expected annual return
• n = years until retirement
• Coast FIRE = amount needed today

Example calculation

If:

• FIRE number = 1,250,000
• Expected return = 7%
• Years to retirement = 30
• Current savings = 150,000

Then:

• Coast FIRE = 1,250,000 ÷ 1.07^30
• Coast FIRE = about 164,000
• Gap = 164,000 - 150,000
• Gap = 14,000

The Coast FIRE number is about 164,000.

What is Coast FIRE?

Coast FIRE is the point where current investments can grow to a full retirement target by a future retirement age without additional contributions. It does not always mean you can stop working immediately.

Why Coast FIRE matters

• shows the value of early savings
• separates retirement investing from current income needs
• helps assess whether contributions can slow down
• supports flexible career planning

When to use this calculator

• checking if current savings are enough to coast
• planning reduced future contributions
• comparing retirement ages
• testing return assumptions

Common mistakes

• assuming Coast FIRE means immediate retirement
• ignoring future expense changes
• relying on one return assumption
• forgetting taxes and fees

Coast FIRE vs FIRE

FIRE means you have enough assets to cover expenses now. Coast FIRE means your current assets may grow enough by retirement age.

Coast FIRE is a milestone on the path to full FIRE.

FAQs

What is Coast FIRE?

Coast FIRE is the amount needed today to grow into your retirement target by a future retirement age.

How do you calculate Coast FIRE?

Divide the FIRE number by one plus expected return raised to the years until retirement.

What is a good Coast FIRE number?

A good Coast FIRE number is one your current savings meet or exceed while using realistic return and expense assumptions.

What is the difference between Coast FIRE and FIRE?

Coast FIRE is future-focused. FIRE means the portfolio can support expenses now.