How to use this calculator
- Enter your age and the age you want to retire, then what you have invested for retirement: your 401(k)s, 403(b)s, IRAs and any account set aside for retirement. Leave out your emergency fund.
- Enter what you add this year, including any employer match. The calculator raises it by 2.5% a year unless you change that under More options.
- Enter the yearly spending you want in retirement at today's prices, including the income tax you expect to pay on withdrawals.
- Choose a withdrawal rate. 4% is the common starting point for a 30-year retirement; a longer one calls for a lower rate.
- If you expect Social Security, turn it on and enter the yearly benefit for the age you plan to claim (at your full retirement age, 67 if you were born on January 2, 1960 or later, you get the full amount). Your Social Security Statement assumes you keep earning what you earn now until you claim, so if you plan to stop earlier, use an estimate with the earnings you expect. For a couple, enter the amount you are confident of for life, such as the larger of the two benefits.
- Try a lower return. The answer depends on it more than on anything else, and the second chart shows by how much. If you pay fund expenses (an expense ratio) or an advisory fee as a share of your balance, enter them under More options.
The numbers already filled in are an example. Replace them with your own.
How it's calculated
1. The savings you need at retirement
Your financial independence number is your yearly spending divided by your withdrawal rate. In the example, $60,000 ÷ 4.0% = $1,500,000 in today's dollars. At 2.5% inflation for 30 years, that is $3,146,351 in dollars of the year you turn 65.
2. The years before Social Security
If Social Security starts after you retire, your savings pay your full spending until it does. The years in between are priced with no growth after inflation, so a bad start in the markets does not shrink them, and the rest of your spending is divided by the withdrawal rate as above. In the example with $24,000 a year from 67: $36,000 ÷ 4.0% = $900,000, plus $48,000 for the 2 years before the benefit starts, a target of $948,000. Counting Social Security never gives a higher target than leaving it out.
3. Your Coast FIRE number
The calculator works back from the target to today at your return, after any yearly investment costs. The result is the target's present value: the amount that compound growth turns into the target by the time you retire. $3,146,351 discounted over 30 years at 7.0% is $413,327: invested today and left alone, that amount is projected to grow to your target by 65. Growth is added once a year and rounded to the cent, and the number is the smallest balance that reaches the target that way.
Spending is in today's dollars and the return is before inflation, so the target is inflated to the retirement year before it is discounted. Skipping that step, and discounting the today's-dollar target at the full 7.0%, would give $197,051 instead of $413,327.
4. When you catch up
Your Coast FIRE number rises every year you wait, because there is one year less for growth. The calculator adds what you save at the start of each year, grows the balance, and finds the first age at which your savings are at least that year's number. In the example, saving $20,000 this year and 2.5% more each year after, you catch up at 49, when the number has grown to $1,065,778 and you have $1,069,996. From then on, with no new savings, your balance is projected to reach $3,158,802 by 65.
5. If you stopped today
The calculator also runs the question the other way. Your $200,000, left alone, is projected to reach $1,522,451 by 65, which is $725,817 in today's dollars. At a 4.0% withdrawal rate that could pay about $29,033 a year at today's prices.
Assumptions and limits
- One average return every year. Real returns vary, and a bad decade early in retirement can cut what savings support (sequence of returns). The withdrawal rate carries that risk for the main target, which is why a lower rate is the more cautious one.
- The 4% convention was tested for 30-year retirements. A longer retirement, or investment costs that continue after you retire, supports a lower rate; the calculator uses the rate you enter.
- One inflation rate raises your spending target and your Social Security; what you add rises by its own yearly increase under More options. In law, Social Security's formula is indexed to average wages until 62 and benefits rise with a price index after that.
- Contributions go in at the start of each year and growth is added at the end, with costs taken after growth. If you save monthly instead, your balance will be somewhat lower than shown, because each month's money has less time to grow.
- No taxes are computed. Your spending figure should include the income tax you expect on withdrawals. Money in traditional 401(k)s and IRAs is taxed when you take it out; Roth money generally is not.
- Money in 401(k)s and IRAs taken before 59½ generally carries a 10% additional tax, with exceptions. If you plan to retire earlier, the calculator does not check which accounts can pay for those years.
- Social Security is your own estimate. The calculator does not work out a benefit or change it when you change the starting age. It treats the benefit as rising with inflation and paid for life, and counts the share you choose.
- Nothing else changes before retirement: no windfalls, withdrawals or one-off costs, and your spending moves only with inflation.
- Coasting means stopping retirement saving, not stopping work. Until you retire, your pay has to cover your spending; the calculator does not check that it does.
- It does not cover a pension or annuity, spouses' separate benefits and ages, survivor benefits, random or historical returns, spending that changes in retirement, or how much more to save to reach your target on time.
Input field details
What to enter in each box, where to find the number, and how this calculator treats it. When two calculators give different answers from the same numbers, it's usually because they handle one of these differently.
Your age now
Your age today, in whole years.
How this tool treats itThe timeline counts whole years from now, one row per age, from your age today to the age you retire.
Allowed range18 to 75
Age you want to retire
The age you want to start living off your savings.
How this tool treats itIt must be after your age now. If it is not, a retirement age one year from now is used, and the result says so.
Allowed range20 to 80
Not includedWhich accounts you can draw on before 59½. Money taken from a 401(k) or IRA before then generally carries a 10% additional tax, with exceptions (26 U.S.C. 72(t)), so if you plan to retire earlier, check which of your accounts can pay for those years.
Invested for retirement now
The total of all your retirement accounts today: 401(k), 403(b), IRAs, HSA money you are investing, and any taxable account you have set aside for retirement.
Where to find itThe latest statement or online balance for each account.
Allowed range$0 to $20,000,000
Not includedEmergency savings, and money meant for a house or any other goal.
You add this year
What goes into your retirement accounts this year, including any employer match.
Where to find itYour pay stub or your plan’s statement shows your own contributions and the match; add anything you put into an IRA.
How this tool treats itAdded at the start of each year, and raised each year by the yearly increase under More options (2.5% unless you change it). Once your savings catch up with your Coast FIRE number, the plan adds nothing more.
Allowed range$0 to $1,000,000
Expected annual return
The average yearly return you expect on your investments, before investment costs and before inflation.
How this tool treats itThe same return is used every year until you retire. Growth is added at the end of each year and rounded to the cent. Returns are an assumption, not a forecast. Over the long run the S&P 500 returned about 10.2% a year nominally (January 1926 to September 2023, computed from Robert Shiller's series, dividends reinvested, before taxes, fees and any advisor cost), while consumer prices rose about 3.0% a year (1926 to 2024, computed from the CPI-U). Neither is what any single decade delivered, and a real portfolio is not an index: you cannot invest directly in one. Every figure this tool produces is a hypothetical illustration of the assumptions you entered.
Allowed range0% to 20%
Not includedReturns that vary from year to year. A bad run of years just before or after you retire can cut what your savings support.
Yearly spending in retirement
What you expect to spend each year once you retire, at today’s prices, including the income tax you expect to pay on your withdrawals.
How this tool treats itRaised with inflation until you retire. Your savings target is this spending, less any Social Security you count, divided by your withdrawal rate.
Allowed range$1,000 to $2,000,000
Not includedThe tax itself, which is not computed: money in traditional 401(k)s and IRAs is taxed when you take it out, and Roth money generally is not. Spending that changes during retirement.
Withdrawal rate
The share of your savings you take in the first year of retirement; after that, the amount rises with inflation.
How this tool treats itYour savings target is your yearly spending from savings divided by this rate: $60,000 at 4% needs $1,500,000. 4.0% is a common starting point, not a rule, and it was tested for 30-year retirements. For a longer retirement, or if you will still pay investment costs once you retire, a lower rate is the more cautious choice.
Allowed range2% to 8%
Count Social Security
Turn on to count the Social Security benefit you expect. It lowers the savings you need.
How this tool treats itOff unless you turn it on, which gives the more cautious answer. When it is on and your benefit starts after you retire, your savings also pay for the years in between, with no investment growth after inflation counted for those years.
Social Security a year at that age
Your estimated benefit for the age you plan to claim, as a yearly amount in today’s dollars: a monthly estimate × 12.
Where to find itYour Social Security Statement, in your my Social Security account.
How this tool treats itYour Statement assumes you keep earning what you earn now until you claim (20 CFR 404.812(d)). If you plan to stop work or earn less before then, use an estimate with the earnings you expect, which is likely to be lower. The amount is not adjusted for the starting age, so if you change the age, enter the benefit for the new one. It is treated as rising with inflation and paid for life.
Allowed range$0 to $100,000
Not includedA pension or annuity that does not rise with inflation, and each spouse’s separate benefit. For a couple, enter the amount you are confident of for life, such as the larger of your two benefits: a spouse’s benefit is reduced by their own (42 U.S.C. 402(k)(3)(A)), so a surviving spouse keeps one benefit, not two.
Starting at age
The age you plan to start your Social Security benefit.
How this tool treats it62 is the earliest age for a retirement benefit (42 U.S.C. 416(l)(2)) and 70 the latest that raises it (402(w)); full retirement age is 67 if you were born on January 2, 1960 or later. If this age is after your retirement age, your savings cover the years in between. If it is at or before your retirement age, the benefit is counted from the day you retire.
Allowed range62 to 70
Inflation
The yearly rise in prices you expect between now and retirement.
How this tool treats itRaises your spending target and your Social Security between now and retirement, so the retirement-year figures are in dollars of that year. 2.5% unless you change it. In law, Social Security is indexed to average wages until 62 and to prices after (42 U.S.C. 415(a), 415(i)); using prices throughout gives no credit for wages rising faster than prices, the cautious direction.
Allowed range0% to 10%
Yearly increase in what you add
How much your yearly contribution rises each year.
How this tool treats it0% keeps it flat; 2.5% keeps pace with the default inflation. Each year’s contribution is this year’s amount raised by the increase once for every year from now, rounded to the cent.
Allowed range0% to 10%
Yearly investment costs
Your fund expenses and any advisory fee, as a yearly percentage of your balance.
Where to find itA fund’s expense ratio is in its prospectus or fact sheet; an adviser’s fee is in your agreement and in the firm’s Form ADV Part 2A.
How this tool treats itTaken from the balance once a year, after growth, until you retire. Leave it at 0% if the return you entered is already after costs. 1% a year of costs has about the same effect as a return one point lower.
Allowed range0% to 3%
Not includedCosts after you retire; allow for those with a lower withdrawal rate.
Show in today’s dollars
Turn on to remove inflation from every figure.
How this tool treats itDivides each year’s figures by one plus inflation, raised to the number of years from now. The answer is the same; only the dollars it is shown in change.
Questions
What is Coast FIRE?
How do I calculate my Coast FIRE number?
What is the difference between Coast FIRE and Barista FIRE?
Should I count Social Security?
What withdrawal rate should I use?
Why does the return I choose change the answer so much?
Once I reach my Coast FIRE number, can I stop saving entirely?
Version history
- September 24, 2026 (version 1.0.0): First version. Finds your Coast FIRE number from your retirement spending, the age you catch up with it if you keep saving, and what your savings would pay for if you stopped today, with an optional Social Security estimate.