Coast FIRE Calculator

Find your FIRE number and your Coast FIRE number: the amount invested today that could grow to fund retirement with no more saving. See the age you would reach it.

Reviewed by Dany, RightSums team · Updated

Runs in your browser. Free, no sign-up.

personal-finance · Daily life · UK & US

Enter your age, the age you want to retire, your yearly spending in retirement at today's prices, a safe withdrawal rate, an expected real return and what you have invested now. The calculator works out your FIRE number, the pot that would cover your spending at that withdrawal rate, and your Coast FIRE number, the amount you need invested today for growth alone to reach it by your retirement age. It tells you if you have hit it, how far you have to go, and the age you would reach it with your monthly saving. The default 4% withdrawal rate is a rule of thumb from past US market studies, not a guarantee, so you can change it. Everything is at today's prices.

Accepted inputs

  • Country and currency (UK, US or Canada)
  • Current age and retirement age
  • Yearly spending in retirement, at today's prices
  • Safe withdrawal rate (default 4%)
  • Expected real return after inflation
  • Amount invested now
  • Monthly saving

Outputs

  • FIRE number
  • Coast FIRE number today
  • If you have reached Coast FIRE, and the gap if not
  • Age you reach Coast FIRE and full FIRE with your monthly saving
  • Monthly saving needed to coast within 5 years
  • Year-by-year table and chart
  • What more saving, a lower withdrawal rate, retiring later or lower returns would change

How to use the Coast FIRE Calculator

  1. Enter your age now, the age you want to retire, your yearly spending in retirement at today's prices and what you have invested.
  2. Set a safe withdrawal rate, 4% by default, and an expected real return after inflation, plus how much you save each month.
  3. The calculator divides your spending by the withdrawal rate to get your FIRE number, then discounts it back to today at your real return to get your Coast FIRE number.
  4. Read if you have reached Coast FIRE, the gap if not, the age your monthly saving gets you there and how the changes suggested would move it.

Frequently asked questions

What is Coast FIRE?

Coast FIRE means you have invested enough that, with no more saving, growth alone should reach your full retirement pot by your chosen retirement age. You still need to earn enough to cover your costs until then, but you no longer need to save for retirement. FIRE stands for financial independence, retire early.

How do you calculate your Coast FIRE number?

Divide your FIRE number by one plus your real return, raised to the number of years until retirement. Spending £40,000 a year at a 4% withdrawal rate gives a FIRE number of £1,000,000. At 30, retiring at 65 with a 5% real return, the Coast FIRE number is £1,000,000 ÷ 1.05 to the power of 35, or £181,290.

How do I work out my FIRE number?

Divide your yearly spending in retirement by your safe withdrawal rate. $50,000 a year at 4% is $1,250,000, and at 3.5% it is about $1,428,571. Take off any pension, Social Security or CPP you expect first, because that part of your spending does not need to come from your investments.

Is the 4% rule safe?

It is a rule of thumb, not a guarantee. It comes from studies of past US stock and bond returns over 30-year retirements. Early retirees may need their money to last 40 years or more, and other markets have done worse, so many people test 3.5% or lower. At 3.5%, £40,000 of spending needs £1,142,857.

How long will it take me to reach Coast FIRE?

It depends on your saving and returns. At 30 with £100,000 invested, spending £40,000 a year in retirement at 65, a 4% withdrawal rate and a 5% real return, saving £500 a month gets you to Coast FIRE at about 52. Saving about £1,530 a month would get you there within 5 years.

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