Most retirement calculators stop at one number: how big your savings will be on the day you quit. That is useful, but it does not tell you whether that number is enough. This retirement planning calculator does both sides of the equation. It projects the nest egg you are on track to build from your salary and savings rate, then sizes the nest egg you actually need to replace your income for the rest of your life, and finally shows the gap between the two. That single gap — a surplus or a shortfall — is the whole point of planning.
Slide any input and the whole picture updates instantly: your projected balance, the balance your spending target demands, and whether you are ahead or behind.
How to Use
- Enter your Current Age and the Planned Retirement Age. The difference is your saving runway — every extra year of compounding is worth more than the last.
- Add your Current Retirement Savings — everything already in 401(k), IRA, pension rollovers and taxable brokerage accounts. If you are just starting, leave it at zero.
- Type your Gross Annual Income. Instead of asking you to guess a contribution dollar amount, this planner asks for your income and a Savings Rate, because that is the habit you actually control.
- Set your Savings Rate as a percentage of gross income. A 10% baseline is the common starting point; 15–20% is where most people need to land to retire comfortably. The calculator multiplies income by this rate to get your annual contribution, and it includes any employer 401(k) match.
- Choose your Expected Annual Return. For a balanced stock-and-bond portfolio, 7% nominal is a reasonable long-run assumption. Drop it to 0% to see the no-growth worst case.
- Expand the planning assumptions to set Inflation / Raise Rate (income grows with prices), Years Spent in Retirement (how long the money must last), your Income Replacement Target (usually 70–85% of pre-retirement pay), and your Safe Withdrawal Rate (the classic 4%).
The result card first shows your Projected Nest Egg at Retirement, then the Nest Egg You Need to fund your target income, and finally the Gap vs Your Target. A positive gap means you are on track; a negative gap tells you how much more to save, how much later to retire, or how much spending to trim.
The Two Maths Behind the Plan
Building the nest egg uses the future-value formula for a lump sum plus an ordinary annuity:
FV = P × (1 + r)ⁿ + C × ((1 + r)ⁿ − 1) / r
Where P is your current savings, C is the annual contribution, r is the annual return, and n is the years until retirement. If the return is 0%, the annuity term simply adds C × n.
Sizing the nest egg you need uses Bengen's 4% rule: divide the annual income you want to spend by a safe withdrawal rate. If you want $80,000 a year and plan to withdraw 4%, you need an $2,000,000 portfolio. Income in retirement is figured in future dollars, so it is first grown by inflation: a $90,000 salary today becomes roughly $198,000 in purchasing-power terms after 32 years at 2.5% inflation.
Worked baseline: age 35, earning $90,000, saving 15% ($13,500 a year), at 7% growth until age 67. Over 32 years those contributions compound to about $1.49 million. With an 80% replacement target and a 4% withdrawal rate, however, that same saver needs roughly $3.97 million — leaving a gap of about $2.48 million. That gap is not a reason to panic; it is a precise instruction to raise the savings rate, delay retirement, or adjust the spending target.
Why Income-Led Planning Beats Guessing a Dollar Amount
Telling a calculator "save $15,000 a year" forces you to know the answer already. Asking for income and a savings rate turns the planning question into a behavior question: can I live on 85% of my pay, or do I need 90%? It also scales automatically with raises — a young worker saving 15% on $60,000 today is on the same lifelong plan as a mid-career worker saving 15% on $120,000 tomorrow, because the rate, not the dollar, is the constant. The 15% savings rate is the industry rule of thumb precisely because it works across incomes when compounded from your 30s.
Examples
Example 1 — The baseline plan. Age 35, income $90,000, save 15%, 7% returns, retire at 67. The annual contribution is $13,500; by 67 that builds about $1.49 million, which pays roughly $4,960 a month at a 4% withdrawal rate. Against an 80%-replacement target that needs about $3.97 million, the plan shows a clear shortfall — the user can nudge the savings rate to 25% or push retirement to 70 to close it.
Example 2 — A zero-return stress test. Age 40 with $50,000 already saved, earning $80,000 and saving 10%, set the expected return to 0%. Over 27 years the $8,000 annual contributions become a flat $216,000 plus the original $50,000 — about $266,000 total. The gap against a $3.1 million needed nest egg is enormous, which is exactly the point: it shows what happens if markets flatline, and why relying on the full 7% is a plan, not a guarantee.
Example 3 — A high saver who is ahead. Age 30, already sitting on $1,000,000, earning $200,000 and saving 20%, at 8% returns retiring at 65. The existing million-dollar balance alone grows to about $14.8 million, and the extra contributions add another $6.9 million, for a projected nest egg near $21.7 million — well above the roughly $8.3 million needed. The gap is strongly positive, meaning this person has financial independence options long before 65.
FAQ
How much money do I need to retire?
A common rule is to save 25 times your desired annual retirement income — the 4% rule in reverse. If you want $80,000 a year on top of Social Security, you need about $2 million. This calculator figures that target for you by growing your future income at inflation, applying your replacement-rate target, and dividing by your chosen safe withdrawal rate.
What is a good savings rate for retirement?
For someone starting in their 30s, 15% of gross income (including any employer match) is the widely recommended baseline; 10% is the minimum to build meaningfully, and 20% or more gets you to an earlier retirement. The savings rate is the single lever you control most directly, and raising it by even 5 percentage points shrinks your retirement gap far more reliably than chasing a higher investment return.
What is the 4% safe withdrawal rule?
Developed by financial planner William Bengen, the 4% rule says you can withdraw 4% of your retirement portfolio in your first year, then adjust that amount for inflation every year after, and the money has historically lasted 30 years or more. Dividing your desired annual income by 4% (0.04) is how this calculator sizes the nest egg you need. If you expect a longer or less certain retirement, lower the rate to 3–3.5%.
Will Social Security cover part of my retirement income?
Yes. Social Security replaces roughly 40% of pre-retirement income for an average earner claiming at full retirement age (67 for people born after 1960). That is why many planners target a 70–85% replacement rate rather than 100%: Social Security and a paid-off home cover a chunk of spending, so your own savings only need to fill the rest.
Does this calculator account for inflation?
Yes. Your future salary is grown by the inflation/raise rate you enter, and your target retirement income is figured in those future dollars, so the nest egg you need is sized in tomorrow's money rather than today's. The 7% expected return is a nominal figure; if you prefer to think in real (after-inflation) terms, enter a lower return of around 4–5% and set inflation to 0%.
What if the calculator says I am behind?
A negative gap is normal for people in their 30s and early 40s. You have four levers: save more (raise the savings rate), retire later (every extra working year both adds contributions and shortens retirement), spend less in retirement (lower the replacement target), or accept a slightly higher withdrawal rate. Try sliding the savings rate and retirement age until the gap turns positive.
Disclaimer
This retirement planning calculator is provided for informational purposes only and does not constitute financial, investment, tax, or legal advice. All figures are estimates based on the assumptions you enter — expected returns, inflation, savings rate and withdrawal rates are not guaranteed and will vary with markets and personal circumstances. Past market performance does not guarantee future results. Social Security benefits, pensions, and tax treatment are not modeled in detail. Consult a fiduciary financial advisor before making retirement or investment decisions.