Retirement income planning comes down to two questions: how much you can draw from your savings each year, and for how long you will need it. The calculators in this section answer the second question with mortality tables rather than a single guess at your lifespan, and every one of them shows its working.
The two things nobody knows in advance
A retirement plan has to cope with two uncertainties at once.
How long the money is needed for. Under the Social Security Administration’s 2023 period life table, a man aged 65 can expect to live another 18.1 years on average, and a woman 20.7. But those are averages. The chance that the man reaches 90 is 24%, about 1 in 4; for the woman it is 35%. At 95 the figures are 8% and 14%. A plan that runs to life expectancy runs short for everyone who lives longer, which at retirement ages is more than half of people.
For a couple the horizon stretches further, because spending usually continues until the second death. Take a man aged 65 and a woman aged 63: the chance that at least one of them is alive 25 years from now is 57%, against 24% for him and 43% for her alone. The joint and last-survivor guide shows how that is worked out.
What the investments earn. Returns vary from year to year, and the order matters: poor returns early in retirement, while withdrawals are being taken, do more damage than the same returns later: see sequence-of-returns risk. A single fixed return gives a clear illustration; simulating many market histories shows the range around it.
Where retirement income comes from
Most households draw on several sources, and they behave differently:
- Social Security pays for life, rises with inflation, and for a married couple continues in part to the survivor. It is a life annuity in all but name.
- Pensions from an employer usually pay for life too, sometimes with a reduced amount for a surviving spouse, and may or may not rise with prices.
- Annuities bought from an insurer turn a lump sum into an income for life. Their value comes from the same mortality and interest maths as a pension: see how life annuities are valued.
- Withdrawals from savings, such as a 401(k) or IRA, are flexible but can run out. Tax-deferred accounts also carry required minimum distributions from a certain age, worked out by dividing the balance by an IRS life expectancy factor.
The gap between what you plan to spend and the guaranteed income is what savings must cover. The bigger that gap, and the longer it lasts, the more savings it takes.
What the calculators in this section do
Each calculator here starts from official data and shows every step for your own numbers.
- How long will my money last projects savings year by year against a spending gap rising with inflation, and reports the age the money runs out together with the chance that you, or your spouse, are still alive at that age.
- The life expectancy calculator gives remaining life expectancy and the chance of reaching 80, 90 and 100, for one person or a couple, from the SSA table.
- The annuity calculator values a fixed-term annuity or an income for life, single or joint, with guarantees and increases, so you can see what a lump sum is worth as income on stated assumptions.
- The IRS life expectancy tables show the Single Life, Uniform Lifetime and Joint and Last Survivor factors with a required minimum distribution estimate.
The full list is below. Each one uses the same engine and the same tables, so the numbers agree across pages.
How to read the results
The answers are illustrations under the assumptions you enter, not predictions. A few habits help:
- Look at a range, not a point. Change the return, inflation or spending by a little and see how far the answer moves. A plan that only works under one set of numbers is fragile.
- Think in chances. For the example couple in the money-last calculator, “in about 5 in 10 households like this, someone is still alive when the money runs out” says more than “the money lasts until about 91”, because it shows how much the answer depends on how long they live.
- Separate today’s dollars from future dollars. The calculators say which they use. Spending figures are usually in today’s dollars and rise with inflation.
- Know what is left out. Taxes, investment fees, health costs and changes in spending through retirement all matter, and each calculator lists what it leaves out.
The maths behind the numbers
Every calculator has a “Show the working” panel that walks through the calculation, with each symbol defined. The Learn section explains the ideas in full: life tables and survival probability for how long, present value and annuity formulas for what money is worth over time, and life expectancy for why the average is a poor planning horizon.
Everything here is an educational illustration, not financial advice. A fee-only fiduciary adviser can look at your full situation, including taxes and the rules for your accounts.
In this section
- How long will my money last?The age your savings run out, and the chance you or your spouse are still alive then.
- IRS life expectancy tables and RMDThe IRS Single Life, Uniform Lifetime and Joint tables, with your required minimum distribution.
- Life expectancy calculatorYour remaining years on the SSA life table, and the chance you, or one of a couple, reach 80, 90 or 100.
- Annuity calculatorThe fair lifetime income a lump sum buys, and the payment, present value or future value of a fixed-term annuity.
Questions
How much money do I need to retire?
It depends on the gap between what you plan to spend and your guaranteed income, and on how long that gap must be covered. A calculator can show how long a given amount of savings lasts at a given spending level, and the chance someone in the household is still alive then. Change the spending or savings to see what moves the answer.
How long will my retirement savings last?
Under fixed assumptions about returns, inflation and spending, savings last until the yearly withdrawals use up the balance. The how long will my money last calculator projects that year by year and compares the result with the chance that you, or your spouse, are still alive at that age.
Why plan past my life expectancy?
Life expectancy is an average, and at retirement ages more than half of people live past it. A plan that ends at life expectancy runs short in more than half of cases. Mortality tables show the chance of reaching each later age, so you can see how far the risk extends.
Do these calculators give financial advice?
No. They are educational illustrations that show what happens under the assumptions you enter, and each one says what it leaves out, such as taxes and fees. A fee-only fiduciary adviser can look at your full situation.