# FIRE Calculator

> Free FIRE calculator. Enter your spending, savings and monthly contribution to see your FIRE number and the age you could retire early.

Source: https://mycoastfire.com/fire-calculator
Last updated: 2026-09-14

See how much you need invested to retire early, and the age you'll get there if you keep saving at your current pace.

## How the calculator works

Your FIRE number is your yearly retirement spending divided by your withdrawal rate. That’s the portfolio you need on the day you stop working. The harder question is when you’ll have it, and that’s what the rest of the calculator answers.

```
FIRE number  = yearly spending ÷ withdrawal rate
real return  = (1 + expected return) ÷ (1 + inflation) − 1

Every month, starting from what you have invested today:
balance      = balance × (1 + real return)^(1/12) + monthly contribution
FIRE age     = your age in the first month the balance reaches the FIRE number
```

It starts with your current balance, grows it by one month’s worth of the real return, adds your contribution, and repeats until the balance reaches your FIRE number. The month that happens is your FIRE age, and the years to go is simply that age minus today’s. If you wouldn’t get there before 100, it won’t show an age at all.

Every figure is in today’s dollars. That’s why the FIRE number line on the chart is flat: prices will rise, but so will your balance, and the real return already accounts for both. It also means your monthly contribution is assumed to rise with inflation, which is roughly what happens if your pay keeps up with prices.

Progress is just your current balance as a share of the FIRE number.

## A worked example

Ben is 32 and has $120,000 invested. He puts $2,500 a month into his 401(k) and IRA, and he thinks $55,000 a year would cover his life in retirement.

His FIRE number at a 4% withdrawal rate is $1,375,000, so he’s 9% of the way there. With 7% returns and 3% inflation, a real return of 3.88%, he reaches it at 55, about 23 years from now.

The monthly contribution is the input Ben controls most directly, so here’s what it does:

| Monthly contribution | Age Ben reaches $1,375,000 |
| --- | --- |
| $1,500 | 62 |
| $2,500 | 55 |
| $3,500 | 51 |

The first extra $1,000 a month moves his date by about 7 years. The second moves it by about 4. That pattern holds for almost everyone: raising your savings rate helps most when it starts low.

Now say Ben decides 4% is too aggressive for a retirement that could run 40 years and switches to 3.5%. His FIRE number rises to $1,571,429, and his date moves to 58. I think that’s a fair price for the margin, but it’s his call, and it’s worth seeing the cost before you make it.

## How do I pick my inputs?

Yearly spending is where most of the error lives. Start from what you actually spent over the last 12 months, then adjust for what retirement changes. A mortgage that will be paid off comes out. Health insurance before Medicare goes in, and it’s often bigger than people expect; [this post covers the options](https://mycoastfire.com/blog/coast-fire-health-insurance-before-65). Include the taxes you’ll owe on withdrawals, since the calculator treats your spending figure as money the portfolio has to supply.

For invested today, add up 401(k)s, IRAs, invested HSA money and taxable brokerage accounts. Leave out your emergency fund and your home.

Your monthly contribution should include any employer match. A match is money going into your account, and leaving it out makes your date look later than it is.

The 7% expected return is a fairly cautious long-run assumption for a mostly-stock portfolio before inflation. If you hold a real share of bonds, try 5% or 6%. The withdrawal rate default of 4% comes from [William Bengen’s 1994 paper](https://www.financialplanningassociation.org/sites/default/files/2021-04/MAR04%20Determining%20Withdrawal%20Rates%20Using%20Historical%20Data.pdf) and the [Trinity Study](https://www.aaii.com/journal/199802/feature.pdf), both of which looked at 30-year retirements. Early retirees often need their money to last longer than that.

## What this calculator can’t tell you

It assumes the same return every year. Real markets don’t work like that, and a bad decade just before you reach your number can push your date back even if the long-run average holds. If you want a range of outcomes instead of one line, the [Coast FIRE Monte Carlo calculator](https://mycoastfire.com/coast-fire-monte-carlo-calculator) runs your plan through 2,000 simulated markets.

It also doesn’t know which accounts your money is in. Withdrawals from 401(k)s and IRAs before 59½ generally come with a [10% additional tax](https://www.irs.gov/taxtopics/tc558) on top of regular income tax. There are exceptions, including one for money in an employer plan if you leave that job at 55 or later, but if you’re planning to stop at 45 you need money you can reach without them.

And it ignores Social Security, which is fine for figuring out when you can stop working but makes your later years look more expensive than they’ll be. The [Social Security version of the Coast FIRE calculator](https://mycoastfire.com/coast-fire-calculator-with-social-security) handles that.

## Should I aim for FIRE or Coast FIRE first?

Your FIRE number is the finish line. Your [Coast FIRE number](https://mycoastfire.com/) is a much smaller checkpoint on the way: the balance that will grow into a normal-age retirement even if you never contribute again. For most people in their 30s it’s a fraction of the full target, and reaching it changes how much a career switch or a pay cut can cost you. If full FIRE is 20 years away, I’d look at both numbers, not just the big one.

## Questions people ask

### What is a FIRE number?

It's the portfolio that can pay for a year of your spending at your withdrawal rate, every year, for as long as you're retired. You get it by dividing yearly spending by the withdrawal rate. At 4%, that's the same as multiplying your spending by 25.

### Is the 4% rule safe if I retire in my 40s?

It was built around 30-year retirements. If you stop working at 45, yours could easily last 45 years, and a lot of people planning that far out use 3.5% for extra margin. Change it under Assumptions and watch how much later your date moves.

### Should I count my home equity?

Usually not, unless you plan to sell and move somewhere cheaper. The FIRE number is about invested money you can draw down. A paid-off house still helps, just in a different place: it lowers the spending figure you enter.

### Does the calculator include taxes or early withdrawal penalties?

No. Build the taxes you expect to pay on withdrawals into your spending figure, and have a plan for reaching retirement-account money before 59½. Taxable brokerage accounts and Roth IRA contributions are the usual ways people cover those years.

## Keep reading

-   [Coast FIRE calculatorWhen you can stop saving and still retire on time.](https://mycoastfire.com/)
-   [Lean FIRE calculatorRetiring early on a smaller budget.](https://mycoastfire.com/lean-fire-calculator)
-   [Fat FIRE calculatorRetiring early without cutting back.](https://mycoastfire.com/fat-fire-calculator)
-   [Types of FIRELean, fat, Coast and Barista side by side.](https://mycoastfire.com/fire-types)