What this calculator does
Find out whether you're on track to retire with the income you want. A retirement plan comes down to two questions. How much will you have when you stop working? And how much do you need to live on the income you want? This calculator answers both.
First, it grows your current savings and monthly deposits until you retire. Then it works out the nest egg you'd need to pay your target income every year until the age you plan for. Social Security and any pension pay part of that income, so they're taken off first.
Comparing the two numbers shows where you stand. If you're short, you'll see how much more to save each month to close the gap. You'll also see the age when the money would run out on your current plan. If you're ahead, you'll see the extra and the yearly income your savings could support instead. You enter all spending in today's dollars, so the goal is easy to picture. The calculator raises it for inflation, the rise in prices over time, for you.
Where it's used
Why this math matters outside the classroom:
- Savings needed. Planners find the lump sum at retirement that could fund a chosen yearly income for a set number of years.
- Inflation-adjusted income. Raising each year's withdrawal with inflation shows how much more savings a steady standard of living needs.
- How long it lasts. Running withdrawals against an assumed return shows the age at which a balance would run out.
- Closing a gap. The future value of an annuity gives the extra monthly saving needed to close a projected shortfall.
Grade level and standards: Grades 11–12; Common Core State Standards for Mathematics HSA.SSE.B.4. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter your current age, the age you plan to retire, and the age you want your savings to last until.
- Enter your current retirement savings, how much you save each month across all accounts, and how much you expect to raise that each year.
- Set the yearly return (how much your investments grow) you expect before and during retirement, and the inflation rate.
- Enter the yearly income you want in retirement and the part that Social Security or a pension will cover, both in today's dollars. Then compare the savings you're on track for with the savings you need.
What the inputs mean
- Plan for savings to last until age
- The age your money needs to last until. Many planners pick an age in the 90s, past average life expectancy. Running out of money late in life is the bigger risk.
- Monthly contribution
- Everything you put toward retirement each month: workplace plan contributions, any employer match, IRAs and other savings set aside for retirement.
- Return during retirement
- Many people hold more bonds and cash once they retire, so a lower return than before retirement is a common, careful choice.
- Yearly income you want in retirement
- The yearly income you'd like before tax, in today's money. A common starting point is a large share of what you earn before retiring. Then adjust it for costs that will go up or down once you stop working.
- Yearly Social Security and pension income
- Income you can count on, in today's dollars. Your Social Security statement on ssa.gov shows estimates for different ages you might start claiming. The calculator assumes this income rises with inflation.
Formula and method
monthly rate: i = (1 + r)^(1 ÷ 12) − 1 saving phase: balance = balance × (1 + i) + contribution, each month first-year withdrawal = (income goal − other income) × (1 + inflation)^years to retirement savings needed = Σ withdrawalₖ ÷ (1 + j)^k over every month of retirement extra monthly saving = shortfall ÷ (((1 + i)^n − 1) ÷ i) affordable income = savings at retirement ÷ (savings needed per $1 of yearly income) + other income
In the formulas, r is the yearly return and i is the matching monthly rate before retirement. The letter j is the monthly rate during retirement. The letter n is the number of months until you retire, and k counts the months of retirement. The symbol Σ means "add them all up".
Before you retire, your savings grow at the monthly rate i. Your deposit is added at the end of each month, and it goes up once a year by the raise you enter.
In retirement, your savings must cover your income goal minus Social Security and pensions. That amount comes out at the start of each month, and it rises with inflation every year, starting from today's dollars. Savings needed is the lump sum that, earning rate j, pays every one of those withdrawals and runs out exactly at your planning age. Finance calls this the present value of the withdrawals.
The shortfall is savings needed minus the savings you're on track for. Dividing it by what $1 a month grows to before retirement gives the extra amount to save each month, the same every month, that would close it. The savings you need goes up in step with the yearly amount savings must cover. So dividing your projected savings by the savings needed per $1 of yearly income shows the income they can really support.
Worked example
You're 35 with $60,000 saved. You put away $800 a month and raise that by 2% a year. You plan to retire at 67 and want your savings to last to 92. You assume 6% returns before retirement, 4.5% after, and 2.5% inflation. You want $70,000 a year in today's dollars, and Social Security will cover $26,000 of that.
- Years until retirement: 67 − 35 = 32, with a monthly rate of 1.06^(1/12) − 1 ≈ 0.00486755.
- Projected savings at 67: about $1,513,563.42, or about $686,810.51 in today's dollars.
- Savings must cover $70,000 − $26,000 = $44,000 a year in today's dollars. After 32 years of inflation, that's about $96,965.31 in the first year of retirement.
- Paying 25 years of those rising withdrawals, while the rest earns 4.5%, takes about $1,902,518.51 at 67.
- Shortfall: $1,902,518.51 − $1,513,563.42 = $388,955.09. Saving about $347.17 more a month, starting now, would close it.
Result: On this plan you'd have about $1,513,563.42 at 67. That's enough for about $61,004.54 a year in today's dollars, including Social Security. The savings would last until about age 85.7.
Understanding the result
Look at the shortfall or surplus first. There are several ways to close a shortfall, and you can test each one here. You could save more each month or retire a little later, which means more years of saving and fewer of spending. You could also lower your income goal, or wait to claim Social Security if that raises your benefit.
The affordable-income figure turns the plan into something real: the yearly lifestyle your savings and other income could pay for, in today's money. The table and chart show your balance climbing until retirement and then shrinking. If the line hits zero before your planning age, the plan counts on returns or spending that are too hopeful.
Assumptions and limitations
- Returns are steady each year, with one rate before retirement and one after, turned into monthly rates.
- Deposits go in at the end of each month and rise once a year. Withdrawals come out at the start of each month and rise with inflation once a year.
- Social Security and pension income rise with inflation and start on the day you retire.
- All figures are before tax. Fees are assumed to be already taken out of the returns.
- This is an estimate to help you learn and plan, not financial advice. Real returns go up and down. The order of good and bad years, especially just after you retire, can change how long your savings last.
- It doesn't include taxes on withdrawals or healthcare costs. It also leaves out required minimum distributions, the amounts the IRS makes you take out of some accounts each year. Spending that changes with age and Social Security claiming rules aren't included either.
- Planning to a fixed age is a simplification, since nobody knows their lifespan in advance.
Frequently asked questions
How much do I need to retire?
It depends mostly on four things. They are the income you want, how much of it Social Security and pensions cover, how long retirement lasts, and the return you earn. The savings-needed figure combines all four. As a rough cross-check, many people start by withdrawing about 4% of their savings a year. That means a nest egg of about 25 times the yearly amount your savings must cover.
Why are the income goal and Social Security in today's dollars?
Because it's much easier to judge what $70,000 buys today than what a much bigger, inflated number buys decades from now. The calculator raises both for inflation, up to and through retirement, so everything stays consistent.
What return should I assume?
Use a careful long-term average for your mix of investments, after fees, and try a lower one too. A slightly lower rate during retirement reflects the safer mix many retirees hold. Small changes in the return make big differences over decades. So treat any single result as one possible outcome.
Is this different from the 401(k) calculator?
Yes. The 401(k) calculator projects one workplace account from your salary, contribution percent and employer match. This calculator looks at all your retirement savings together. It also adds the spending side: what you need, how long it lasts and how to close a gap.
Does retiring later help much?
Usually a lot. Each extra working year adds another year of saving and growth, and takes away a year of withdrawals. Depending on when you claim, it can also raise your Social Security benefit. Try moving the retirement age by two or three years to see the difference.
How this calculator is checked
Method: Month-by-month accumulation at the effective monthly rate; present value of inflation-indexed annuity-due withdrawals for the savings needed; future value of an ordinary annuity for the extra monthly saving. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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