Coast Number Calculator
Your coast number is the amount you need invested today so it grows to your retirement target with no further saving. Reaching it changes the quit conversation, because you only need to cover today's costs, not fund retirement too. Enter your numbers to see your coast number and whether you are already there.
Fill in your numbers, results update as you type. Nothing you enter is stored or sent anywhere.
Reading your result
The big number is your coast number: the amount that, invested today and left untouched, should grow to your target by your retirement age at the return you chose. If you entered what you already hold, the result tells you whether you have reached it, and by how much you are over or short.
Coasting does not mean you can stop working. It means your retirement is on track without further contributions, so a job only has to cover your current living costs. That is what can make a pay cut, a career change, or a planned break feel affordable, even though you still need income for the years between now and retirement.
How to set the inputs honestly
- Set your target in today's money. A common method is annual retirement spending times 25, which reflects a four percent withdrawal rate. Because the return is real, after inflation, you do not need to inflate the target.
- Choose a conservative return. Future returns are uncertain, and a lower assumption raises the amount you need now, which is the safer error. Four to six percent real is a common range.
- Count only retirement investments. Enter long-term invested money in the currently-invested field, not your emergency fund or quit runway, which serve a different purpose.
- Treat it as a long-term check, not a quit budget. Your coast number is about retirement being on track. The gap you are quitting into still needs its own runway. Retirement accounts guide
A worked example
Sam is 35, plans to retire at 65, and wants a target of 1,000,000 in today's money, assuming a 5 percent real return. That is 30 years of growth, so the coast number is 1,000,000 divided by 1.05 to the power of 30, which is about 231,000.
If Sam already has 250,000 invested, the result shows he is past his coast number by roughly 19,000. His retirement is on track without adding another cent, which means a lower-paid role he enjoys more, or a deliberate break, becomes a question of covering today's costs rather than retirement too. He still needs a runway for the gap, but the long-term pressure is off.
Methodology, in plain English
The coast number is the present value of your target. It equals your target retirement amount divided by one plus your real annual return, raised to the power of the years until retirement. Years equal retirement age minus current age. If you enter your current investments, the tool compares them with the coast number to show a surplus or shortfall. The return is real, after inflation, so the target stays in today's money. The model assumes a single average return with no further contributions and no tax on growth, real markets vary year to year, so treat the figure as a planning guide. Educational estimate, not financial advice. Full assumptions on the methodology page.
The mistakes that distort a coast number
Using a nominal return
If you use a return that ignores inflation, you must also inflate the target. Easier to use a real return and keep the target in today's money.
Assuming an optimistic return
A high return shrinks the number you think you need. Choose a conservative figure, the cost of being wrong is undersaving. How much to save
Counting your emergency fund
Coasting is about long-term investments. Cash you need for the gap or emergencies is not part of the coast number. Size your cushion
Reading it as permission to retire
Coasting covers retirement, not the years before it. You still need income, and a runway, for the gap you are quitting into.
Read next
Retirement Accounts After Quitting
401(k), pensions, RRSP, super, KiwiSaver, CPF, what happens to each when you leave.
How Much to Save Before Quitting
Build the savings number for the gap, separate from your retirement coast.
Savings Goal Calculator
Plan the monthly saving to reach any target, including your coast number.
Frequently asked questions
What is a coast number?
Your coast number, sometimes called Coast FIRE, is the amount you need invested today so that, with no further contributions, it grows to your retirement target by the time you retire. Once you reach it, your existing investments can coast to the finish line on their own, and you only need to earn enough to cover today's living costs.
How is the coast number calculated?
It is the present value of your retirement target. The calculator divides your target nest egg by one plus your expected real return, raised to the number of years until retirement. The longer you have until retirement and the higher the return, the smaller the amount you need invested now, because compounding does more of the work.
What return rate should I use?
Use a real return, meaning after inflation, so your target can be expressed in today's money. A figure around four to six percent is a common long-run assumption for a diversified portfolio, but it is only an assumption. Lower it to be conservative, since future returns are uncertain and a smaller assumed return raises the amount you need now.
Does reaching my coast number mean I can retire now?
No. It means your retirement is on track without further saving, not that you can stop working. You still need income to cover your current living costs until retirement age. Coasting is about easing off retirement contributions, which can free up money or make a lower-paid but better-fitting job viable, not about retiring early.
People also ask
What target retirement amount should I use?
A common starting point is your expected annual retirement spending multiplied by twenty-five, which reflects a four percent withdrawal rate. If you expect to spend forty thousand a year, that is a target of one million in today's money. Adjust for your own situation, including any pension or state benefits you expect to receive.
Does reaching my coast number affect a decision to quit?
It can ease it. If your retirement is already coasting, you no longer need a job that funds heavy retirement saving, only one that covers your current costs. That can make a career change, a pay cut for better work, or a planned break more financially comfortable. It does not replace a runway for the gap itself, which you still need to plan.
Is this calculator free and private?
Yes. It is free with no signup, and every calculation runs in your browser, so nothing you type is stored or sent anywhere. The PDF summary is generated locally on your device.
Plan the gap, not just the finish line
Coasting covers retirement. The years before it still need a runway. The Quit My Job Calculator turns your savings and burn into a readiness verdict for the gap ahead.
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