Coast FIRE calculator
Your coast number is the balance that grows into your retirement on its own. Five numbers tell you if you are there.
Classic coast. Your investments cover all of your spending in retirement. An example, 32 years old and retiring at 65. Change any figure and it recomputes.
Everything you live on, the fun included.
What counts as spending
Everything you live on, the fun included. Big repeat costs like a car or a roof go in as a yearly average. Leave out what you save and invest, and one-off goals. Debt payments that end before your freedom date stay out as well.
Your coast number
Age 35
About 3 years 5 months from now at your current pace, with $162,301 invested by then.
- Coast number today
- $128,682
- You have invested
- $85,000, 66% of it
- Retirement number at 65
- $1,200,000
Growth of 7% a year after inflation. Retirement number is 25 times yearly spending. Today's dollars throughout.
What a raise does to that age
After 30% tax, the rest invested, spending flat.
- $5,000 a year8 months sooner, stop saving at 34
- $10,000 a year1 year 2 months sooner, stop saving at 34
- $20,000 a year1 year 9 months sooner, stop saving at 33
| Raise | Invested each month | Sooner by | Stop saving at |
|---|---|---|---|
| $5,000 a year | $292 | 8 months | Age 34 |
| $10,000 a year | $583 | 1 year 2 months | Age 34 |
| $20,000 a year | $1,167 | 1 year 9 months | Age 33 |
Get the formula and every assumption, by email.
The email restates the plan on this screen. We do not keep your figures, only the address to send it to.
Your plan, by email. One tap in that email deletes everything we hold. If you tick the box we also keep the figures needed for two more emails, and the same tap deletes them. Privacy.
How to read it
The coast number is the target for today only. It rises every year you wait, because there is less time left for growth. A 32 year old spending $4,000 a month needs $128,682. The same person at 40 needs $221,099. If you are under the line, the calculator walks forward month by month. Your balance grows at 7% a year and your monthly saving goes in at the end of each month. The line climbs too. The first month your balance meets the line is your crossing.
Take Maya, the example the tool opens on. She is 32, has $85,000 invested, adds $1,200 a month, lives on $4,000 a month, and plans to retire at 65. Her retirement number is $1,200,000, which is 25 times $48,000 a year. Today's coast number is $128,682, and she has 66% of it invested. At her current pace she crosses the line in 3 years 5 months, at 35. After that her investments grow into her retirement without another dollar from her, and every dollar she earns is hers to spend.
The percent funded tells you how much of today's number you already have invested. Anything over 100% means you can stop now if you choose to, and the tool says so in one word.
The age is an estimate at your current saving rate. Save more and it comes sooner. Spend less in retirement and the whole target drops, so the coast number drops with it. Push retirement later and the number drops too, because the money has more years to grow.
If the result says you will not reach the line before your retirement age, your saving pace is too small to catch the line. If 7% of the gap is more than you save in a year, the gap grows faster than you fill it. The fix is more saving, a lower spending target, or a later retirement age.
The math
coast number = retirement number ÷ 1.07 ^ (years until retirement)
retirement number = 25 × yearly spending
Start with what you will spend in a year of retirement. Multiply by 25. That is the 4% rule written as a target. A portfolio that pays out 4% of its starting value each year has lasted 30 years or longer in most historical periods, not all. Twenty-five times spending is the same number written the other way around. Then divide by 1.07 for each year until you retire. Maya has 33 years until 65. Growth of 1.07 raised to 33 is 9.33, so $1,200,000 divided by 9.33 is $128,682.
The 7% is a real return, meaning after inflation. It is what a broad stock index has averaged after inflation over long stretches. Using a real return means every figure on this page is in today's dollars. Your $4,000 a month of spending stays $4,000 a month, and the target stays $1,200,000, with no inflation math to do in your head.
The crossing uses the same rate, compounded monthly. Each month your balance grows by 0.565%, which is 7% a year, then you add your monthly saving. The line for that month is the retirement number divided by 1.07 raised to the years still left.
The raise rows take a gross annual raise and keep 70% of it. Tax takes the other 30%, our standing assumption for someone in the 22% federal bracket, plus 7.65% for Social Security and Medicare. What is left is divided by 12 and added to your monthly saving, with your spending held flat. Most coast calculators leave the raise out, and it is the lever that moves the age the most. A $10,000 raise gives Maya $583 a month more to invest after tax. That moves her crossing 14 months sooner, to 34.
What the calculator assumes
- Growth is 7% a year after inflation, every year, with no bad decades. Real markets do not move in a straight line, and the order of returns matters. Treat the result as a pace, and rerun it once a year.
- Spending is what you will live on in retirement, in today's dollars. The fun is included. Leave out what you save and invest, one-time goals, and debt payments that end before your retirement date.
- The retirement number is 25 times spending, which is a 4% withdrawal rate. Longer retirements argue for more, closer to 28 or 30 times. Use 28 or 30 times for a retirement longer than 30 years.
- The raise keeps 70% after tax. State income tax is not in that number. If your state taxes income, you keep a little less than the row shows.
- No Social Security or pension is counted in classic mode. Add either one as part-time pay in Barista mode and the target drops the right way.
- Age is read in whole years. A crossing 41 months out from 32 prints as 35.
Coast numbers by age
Every figure in this table comes from the same formula, at 7% real growth, with retirement at 65. Find your age and the monthly spending closest to yours.
| Age | $3,000 a month | $4,000 a month | $5,000 a month | $6,000 a month |
|---|---|---|---|---|
| 25 | $60,102 | $80,136 | $100,171 | $120,205 |
| 30 | $84,297 | $112,396 | $140,494 | $168,593 |
| 35 | $118,230 | $157,641 | $197,051 | $236,461 |
| 40 | $165,824 | $221,099 | $276,374 | $331,649 |
| 45 | $232,577 | $310,103 | $387,629 | $465,154 |
| 50 | $326,201 | $434,935 | $543,669 | $652,403 |
Read across a row and the number grows in step with spending, because the retirement number does. Read down a column and it grows faster, because every five years of waiting takes five years of compounding off the table.
When part-time pay, a pension or a spouse changes it
Barista FIRE means you reach the coast line and then take a job that covers part of your spending. The name comes from people who took part-time work at coffee shops for the health insurance. Your investments cover the rest, so the target is smaller and the line is closer.
The calculator handles it with one extra input, the monthly pay you expect from that job. It subtracts that pay from your spending before the multiply by 25. Maya spends $4,000 a month. With $1,500 a month of part-time pay, her investments only need to cover $2,500. Her retirement number falls from $1,200,000 to $750,000, and her coast number today falls from $128,682 to $80,426. With $85,000 invested she already clears it. Switch to Barista mode to run your own version.
Couples, Social Security, and a pension
A couple runs one calculation, not two. Add both balances into the invested figure, both monthly savings into the saving figure, and the household spending into spending. Use the younger partner's age if you want the more cautious number, since it leaves more years for growth and sets a lower coast number today.
Social Security and a pension both lower the target the same way part-time pay does. Switch to Barista mode and type the monthly benefit you expect in place of the part-time pay. A $2,000 a month benefit against $4,000 a month of spending halves the retirement number. Be careful with the age. Social Security starts at 62 at the earliest, so counting it only makes sense if your retirement age is at or after the age the checks begin.
Questions people ask
What is coast FIRE?
Coast FIRE is having enough invested that it grows into a full retirement fund by itself. You keep working to pay your bills, but you can stop saving for retirement. FIRE stands for financial independence, retire early. Coast is the version where you stop saving early rather than stop working early.
What is my coast FIRE number?
It is your full retirement number divided by your expected growth over the years until you retire. Spend $4,000 a month, retire at 65, and at 32 the number is $128,682 at 7% real growth.
How do I calculate my coast FIRE number?
Multiply your yearly retirement spending by 25. Then divide by 1.07 raised to the power of the years until you retire. A 30 year old spending $5,000 a month has 35 years to go. Their target of $1.5 million divided by 1.07 to the 35th power is $140,494.
What does coast FIRE mean for my job?
It means you can take the job that pays less but that you like more. Your retirement is funded. You only have to cover the cost of living today.
Can I coast FIRE right now?
If your invested balance is at or above your coast number, yes. If you are at or above it, you can coast now. If you are under it, the calculator shows the age you reach it at your current saving pace.
How much do I need for coast FIRE?
It depends on three things. Your monthly spending in retirement, your age, and the age you want to retire. A 25 year old spending $3,000 a month needs $60,102. A 45 year old spending $6,000 a month needs $465,154.
What is the difference between coast FIRE and barista FIRE?
Coast FIRE means you stop saving and keep a full-time job for your bills. Barista FIRE means you stop saving and take part-time work that covers part of your bills, with the investments covering the rest. Barista needs a smaller target, because the part-time pay does some of the work.
Does coast FIRE mean I stop investing?
It means you can. Many people keep saving anyway, because saving after the coast line moves the retirement date earlier. Reaching the line means saving becomes optional.