Retirement Calculator
The question behind every retirement plan is simple: will the money last? This calculator projects what your savings and monthly contributions could grow to by your retirement age, translates that pot into today’s money so that inflation does not flatter the number, and shows the yearly income it could sustain at your chosen withdrawal rate. It then works backwards: if you are short of your goal, it tells you the monthly saving that would close the gap. It uses a simple constant-return model, which makes the trade-offs between saving more, retiring later and expecting more from investments easy to see — but real markets are bumpy, so treat it as a planning aid, not a forecast.
How to use the retirement calculator
- Enter your age, the age you hope to retire and your current retirement savings.
- Add what you save each month, and an expected return and inflation rate. Be conservative rather than hopeful.
- Enter the yearly income you would like in retirement, in today’s money, and a withdrawal rate (4% is the classic starting point).
- Compare the sustainable income with your goal, then try retiring a few years later or saving a little more to see what moves the result most.
Formula
Future value = current savings × (1 + i)n + monthly saving × [((1 + i)n − 1) ÷ i], where i is the monthly return (annual ÷ 12) and n the number of months to retirement. Today’s-money value = future value ÷ (1 + inflation)years. Sustainable income = today’s-money value × withdrawal rate. The saving needed to hit a goal solves the same equation for the monthly amount, using the goal grown by inflation and divided by the withdrawal rate.
Worked examples
Saving $1,000 a month from age 35
With $50,000 saved, $1,000 a month, a 6% return and 2.5% inflation, a 35-year-old retiring at 65 could have $1,305,643.80 — about $622,456.13 in today’s money. At a 4% withdrawal rate that supports $24,898.25 a year in today’s money against a goal of $60,000, so the plan shows a shortfall against goal of $35,101.75 a year.
How much to save from zero
Starting from nothing at 35, reaching $60,000 a year (today’s money) at 65 under the same assumptions needs about $3,132.21 a month.
The effect of waiting
Delaying the start of the same plan by ten years (age 45, still retiring at 65) cuts the projected pot to $627,551.12 — the last years of compounding are worth far less than the first.
What moves a retirement plan most
The four levers
| Lever | Effect |
|---|---|
| Save more | Raising the monthly amount from $1,000 to $1,500 lifts the projected pot from $1,305,643.80 to $1,807,901.32 |
| Retire later | Retiring at 67 instead of 65 gives $1,497,101.13 |
| Higher return | A 7% instead of 6% return gives $1,625,795.87 |
| Spend less | A smaller income goal shrinks the pot you need, and every dollar of spending you avoid is a dollar you do not have to replace |
Remember what is not included
Taxes on withdrawals, Social Security or a state pension, employer matches and one-off costs are outside this model. Add guaranteed income to the sustainable income shown to see your whole picture, and revisit your plan yearly. For the bigger idea of retiring early, see the FIRE calculator.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- A 40-year-old has $80,000, saves $800 a month, expects 6% growth and 2.5% inflation and retires at 65. What will the pot be worth in today’s money?
Show answer
Projected savings at retirement: $911,592.75 · In today’s money (inflation-adjusted): $491,704.55
Common mistakes to avoid
- Ignoring inflation. A million dollars in 30 years buys much less than a million today — always look at the today’s-money figure.
- Assuming a high, smooth return. Real returns vary year to year and the order of returns matters, especially just before and after retirement.
- Forgetting taxes and fees. This model is pre-tax and pre-fee; taxes on withdrawals and fund fees reduce what you actually spend.
- Leaving out Social Security, a state pension or workplace pension. Those can cover a meaningful part of the goal — this tool shows what your own savings provide.
- Planning to exactly your life expectancy. A longer-than-average life is the risk retirement plans exist to cover.
Frequently asked questions
How much do I need to retire?
A common rule of thumb is about 25 times your yearly spending, which equals a 4% withdrawal rate. The calculator shows what your projected savings support and what you would need to save to reach your own goal.
What is the 4% rule?
It comes from historical studies of US portfolios: withdrawing 4% of the starting balance in the first year and adjusting for inflation after that has historically lasted about 30 years. It is a guideline, not a guarantee, and may be too high for longer retirements.
What return should I assume?
Many planners use roughly 5–7% a year before inflation for a balanced portfolio, and lower for cautious ones. Try a few values; a plan that only works at a high return is fragile.
Why show today’s money?
Because a large future number can be misleading. Dividing by inflation tells you what that money will actually buy in terms you can compare with your living costs today.
Does this include Social Security or a pension?
No. Add any guaranteed income to the sustainable income shown to see your total picture.
Is this financial advice?
No. It is an educational estimate. A qualified adviser can take account of your tax position, benefits and risks.
Sources and further reading
By Thomas M, Registered Investment Adviser (South Carolina), who launched his own financial advisory firm in 2010. Last reviewed September 26, 2026. Found a mistake? Tell us; see our editorial policy.