Quick answer
A retirement calculator projects the pot you will have at retirement from your current savings, monthly contributions and an assumed return. $80,000 saved by age 35, plus $800 a month at a 7% return, grows to about $1,625,000 by 65 — roughly $670,000 in today's purchasing power after 3% inflation.
How the Retirement Calculator works, step by step
Enter your current age, retirement age, current savings, monthly contribution, expected return, the annual spending you expect in retirement and your life expectancy. The calculator compounds the existing pot monthly for the full period and each monthly contribution for the time it is invested, then plots the balance year by year to retirement.
Then judge the result against spending, not against the headline number. The tool sets two targets: simple drawdown (annual spending times years in retirement) and the 4%-rule target (spending times 25). With $40,000 of annual spending and a life expectancy of 90, both targets are $1,000,000 — and the projected pot supports about $5,418 a month of spending over 25 years. The two targets answer different questions: drawdown assumes the pot is spent to zero by life expectancy, while the 4%-rule target assumes withdrawals of 4% a year, adjusted for inflation, with the pot intended to last indefinitely.
If the projection falls short of the target, the tool solves for the extra monthly saving that closes the gap. At a 5% return with $60,000 of annual spending, the target is $1,500,000 against a projected $1,023,226 — a $476,774 shortfall that needs about $573 a month extra, starting now. The earlier the extra saving starts, the smaller it needs to be.
Run the pessimistic case before trusting the plan. Drop the return to 5% and the same saver reaches roughly $1,023,226. Retire at 60 instead of 65 and the pot falls to about $1,106,091 — five fewer years of contributions and growth, and five more years of spending. Contribution and retirement age are the levers you control; the return is not.
The projection covers your own savings only. Social Security is a separate income stream — the average retired worker received about $2,071 a month in January 2026, and benefits replace roughly 40% of pre-retirement income for a medium earner. Taxes and inflation are also outside this projection: the $1,625,000 headline is nominal, and its purchasing power at 3% inflation is about $670,000 in today's money.
The formula
Projected pot = Current savings × (1 + r/12)^(12 × years) + Monthly contribution × [((1 + r/12)^(12 × years) − 1) / (r/12)]. Target = annual spending × years in retirement; 4%-rule target = spending × 25.
Worked example — try it on the calculator above
Worked example: saving from 35 to 65 at 7%
Current savings $80,000, contributions $800 a month, return 7%, horizon 30 years. The existing pot grows to about $649,320 and the contributions — $288,000 paid in — grow to about $975,977. Total: roughly $1,625,297. A 4% first-year withdrawal implies about $65,012 a year of portfolio income, before Social Security and taxes. Discounted at 3% inflation, the pot is about $670,000 in today's money, which is the figure to compare with the retirement spending you have in mind.
Frequently Asked Questions
How much should I have saved by each age?
A widely used guideline (Fidelity's) suggests about 1× your salary saved by 30, 3× by 40, 6× by 50 and 10× by 67, assuming retirement at 67 and a conventional lifestyle. It is a checkpoint, not a rule — a late start can be offset by higher contributions, later retirement, or lower planned spending.
What return should I assume before retirement?
Many planners use 6% to 7% nominal for a diversified stock-heavy portfolio and 5% for a balanced one, then test 2 points lower. Using 10% because it is the long-run US stock average leaves no margin for a bad decade near retirement, when the damage is hardest to repair.
Does the calculator include Social Security?
This projection covers your own savings only. Social Security is a separate income stream: the average retired worker received about $2,071 a month in January 2026, and benefits replace roughly 40% of pre-retirement income for a medium earner, claimed between 62 and 70. Add your estimated benefit on top of what the portfolio can sustainably pay.
How does retiring five years earlier change the result?
Twice over: five fewer years of contributions and growth, and five more years of spending. In the worked example, retiring at 60 instead of 65 cuts the pot from about $1,625,000 to about $1,106,000 — roughly a third less, from a change that feels like a sixth of the timeline.
Estimates, not advice. This calculator provides educational estimates based on the inputs you enter and the assumptions shown on this page. It is not financial, tax or investment advice, and it cannot see your full situation. Verify important figures against official sources, and consider a qualified professional for decisions about your own money. See our Disclaimer and Methodology.