acalculator

Have I saved enough for Coast FIRE?

Enter your age, when you want to retire, your spending, and what you have invested. See your Coast FIRE number and when you could stop saving.

Your numbers

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Returns are never guaranteed.
Your Coast FIRE number today
$329,443.28

To coast to $1,250,000.00 by age 65, you need $329,443.28 invested today; you have $100,000.00, so you still need $229,443.28.

Your FIRE number
$1,250,000.00
Still needed today
$229,443.28
You can coast from age
47.5
Invested at retirement
$1,250,357.06
Months
420

Your Coast FIRE number today: $329,443.28. To coast to $1,250,000.00 by age 65, you need $329,443.28 invested today; you have $100,000.00, so you still need $229,443.28.

When can you coast?

What does each year look like?

The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use

How to calculate

Computes your Coast FIRE number: what you need invested today to reach your FIRE number by your retirement age with no more saving, and when you get there.

Example with the default inputs (Your age 30, Retirement age 65, Yearly spending in retirement $50,000.00, Invested today $100,000.00, You save each month until you coast $1,500.00, Expected yearly return 7%, Prices rise each year by 3%, Safe withdrawal rate 4%): To coast to $1,250,000.00 by age 65, you need $329,443.28 invested today; you have $100,000.00, so you still need $229,443.28.

Method: Coast FIRE number = (yearly spending ÷ withdrawal rate) ÷ (1 + real return)^(retirement age − age), with real return = (1 + R) ÷ (1 + inflation) − 1; each month the balance grows at the monthly real rate plus your saving until it reaches that month’s Coast FIRE number.

  • All amounts are in today’s money: your saving and spending rise with prices.
  • The return and inflation stay the same every year. Real returns go up and down.
  • You stop saving once you reach Coast FIRE, and add nothing more until retirement.
  • The withdrawal rate is a rule of thumb from past market returns, not a guarantee.
  • Taxes, fees, and Social Security are not included.
  • This is an estimate for planning, not financial advice.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Your age 30, Retirement age 65, Yearly spending in retirement $40,000.00, Invested today $50,000.00, Expected yearly return 7%, Prices rise each year by 0%, Safe withdrawal rate 4% gives Your FIRE number $1,000,000.00, Your Coast FIRE number today $93,662.94, Still needed today $43,662.94.Source: hand calculation in content.mdx: 1,000,000 ÷ 1.07^35
  2. Your age 30, Retirement age 65, Yearly spending in retirement $60,000.00, Invested today $100,000.00, You save each month until you coast $500.00, Expected yearly return 7%, Prices rise each year by 3%, Safe withdrawal rate 4% gives Your FIRE number $1,500,000.00, Your Coast FIRE number today $395,331.94.Source: hand calculation in content.mdx: 1,500,000 × (1.03 ÷ 1.07)^35
  3. Your age 30, Retirement age 80, Yearly spending in retirement $24,000.00, Invested today $50,000.00, You save each month until you coast $1,000.00, Expected yearly return 3%, Prices rise each year by 3%, Safe withdrawal rate 4% gives Your FIRE number $600,000.00, Your Coast FIRE number today $600,000.00, You can coast from age 75.833333.Source: hand calculation in content.mdx: at a 0% real return, (600,000 − 50,000) ÷ 1,000 = 550 months
  4. Your age 40, Retirement age 60, Yearly spending in retirement $40,000.00, Invested today $500,000.00, Expected yearly return 7%, Prices rise each year by 2%, Safe withdrawal rate 4% gives Still needed today $0.00, You can coast from age 40.Source: hand calculation in content.mdx: $500,000 is above the Coast FIRE number, so you coast now

How it is worked out

With the yearly return R and inflation π (as decimals), the real return is ρ = (1 + R) ÷ (1 + π) − 1, and everything is in today’s money.

  • Your FIRE number F = yearly spending ÷ safe withdrawal rate.
  • With T = retirement age − your age, your Coast FIRE number today = F ÷ (1 + ρ)^T.
  • Still needed today = Coast FIRE number − what you have invested, or $0 if you have more.

When you can coast. The calculator runs month by month for 12 × T months at the monthly real rate i = (1 + ρ)^(1/12) − 1. After m months, the Coast FIRE number is F ÷ (1 + ρ)^((12T − m) ÷ 12). Each month:

  1. Growth: balance = balance × (1 + i).
  2. Until you coast, your monthly saving is added at the end of the month (an empty saving counts as $0).
  3. If the balance is now at or above that month’s Coast FIRE number, you coast from then on: no more saving.
  • You can coast from age = your age + (the first month in which you reach it) ÷ 12, or your age if you are already there today. If you do not reach it before retirement, "Not before your retirement age" is shown instead.
  • Invested at retirement is the balance after 12 × T months.

If the retirement age is not more than your age, there is no answer.

Assumptions

  • The return and inflation stay the same every year, and your saving rises with prices.
  • You stop saving once you reach Coast FIRE.
  • Taxes, fees, and Social Security are not included.
  • This is an estimate for planning, not financial advice.

Worked examples by hand

$40,000 a year, 4%, age 30, retiring at 65, 7% return, 0% inflation, $50,000 invested. F = 40,000 ÷ 0.04 = $1,000,000. T = 35, and 1.07^35 = 10.676581, so the Coast FIRE number is 1,000,000 ÷ 10.676581 = $93,662.94. You still need 93,662.94 − 50,000 = $43,662.94.

$60,000 a year, 4%, age 30, retiring at 65, 7% return, 3% inflation. F = $1,500,000. (1.03 ÷ 1.07)^35 = 0.2635546, so the Coast FIRE number is 1,500,000 × 0.2635546 = $395,331.94.

$24,000 a year, 4%, age 30, retiring at 80, 3% return, 3% inflation, $50,000 invested, $1,000 a month. The real return is 0, so the Coast FIRE number is F = 24,000 ÷ 0.04 = $600,000 at every point. You reach it after (600,000 − 50,000) ÷ 1,000 = 550 months, at age 30 + 550 ÷ 12 = 75.8.

$40,000 a year, 4%, age 40, retiring at 60, 7% return, 2% inflation, $500,000 invested. The Coast FIRE number is 1,000,000 × (1.02 ÷ 1.07)^20 = $383,997.04. You have more, so you still need $0 and can coast from age 40.

Other questions people ask

What is Coast FIRE?

Coast FIRE means you have invested enough that, with no more saving, growth alone would reach your FIRE number by your retirement age. From then on, your pay only has to cover your spending, not your retirement saving.

How is the Coast FIRE number calculated?

Start with your FIRE number: yearly spending ÷ safe withdrawal rate. Then discount it back to today at the real return: Coast FIRE number = FIRE number ÷ (1 + real return)^(years to retirement). $1,000,000 needed in 35 years at a 7% real return is $93,662.94 today.

What is the difference between FIRE and Coast FIRE?

With FIRE you have enough to stop working now. With Coast FIRE you have enough to stop saving now, but you keep working to pay for your life until your investments reach the full FIRE number at your retirement age.

Why use a real return?

Your spending will rise with prices, so everything is in today’s money. The real return is (1 + return) ÷ (1 + inflation) − 1: a 7% return with 3% inflation is a 3.88% real return. If inflation is higher than the return, the real return is negative and the Coast FIRE number is higher than the FIRE number.

What if my return is lower than I expect?

Then your investments grow more slowly and you may not reach your FIRE number by retirement. Returns are never guaranteed, so try a lower return, or a lower withdrawal rate, to see a more cautious number.