Retirement Calculator
Project your retirement balance from today's savings and monthly contributions, then translate it into the sustainable income it could actually support.
Retirement Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: A retirement projection compounds your current savings and future contributions to your retirement date, then applies a safe withdrawal rate — commonly 4% annually — to estimate the sustainable income that balance can support without depleting the capital prematurely.
Formula
Sustainable income is then Balance × withdrawal rate, following the safe-withdrawal-rate convention.
Worked Example
- Find the horizon. Age 65 − age 32 = 33 years, or 396 monthly periods.
- Grow existing savings. $45,000 at 7% for 33 years = $450,316.68.
- Accumulate contributions. $800 per month over 396 periods = $1,235,250.85.
- Total the balance. $1,685,567.53 at retirement.
- Apply the 4% rule. $1,685,567.53 × 4% = $67,422.70 a year, or $5,618.56 a month.
Analyst's note. Contributions total $316,800 but the balance reaches $1,685,567.53 — investment growth supplies 78.5% of the outcome. In today's purchasing power that balance is worth about $635,503 at 3% inflation, which is the number worth planning against.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Testing whether your current rate is enough
Compare the sustainable monthly income against your expected expenses in retirement. If there is a shortfall, the three levers are contributing more, working longer, or accepting a lower income — and the first is usually the least painful.
Understanding the cost of delay
Advance the current age by five years while holding everything else constant. The reduction is generally far greater than five years of contributions, because the lost years are the ones that would have compounded the longest.
Coordinating account types
Model total savings here, then optimise the tax treatment across accounts using the 401k Calculator and the Roth IRA Calculator.
Methodology & Editorial Standards
Contributions are treated as end-of-month (ordinary annuity) and compounded monthly at the expected annual return divided by twelve. Sustainable income applies a constant withdrawal rate to the projected balance, following the safe-withdrawal-rate convention originating in the Trinity Study. This model assumes a constant return, which no real market provides, and does not model sequence-of-returns risk, taxes, Social Security, or changing contribution levels. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Retirement Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How much do I need to retire?
A common benchmark is 25 times your annual spending, which corresponds to the 4% withdrawal rule. If you expect to spend $60,000 a year, that implies a target of roughly $1,500,000. Adjust upward for early retirement or a longer expected lifespan.
What is the 4% rule?
A guideline from the Trinity Study suggesting that withdrawing 4% of your initial portfolio in the first year, then adjusting for inflation, historically survived 30-year retirements in most scenarios. It is a planning heuristic, not a guarantee, and many now argue for 3% to 3.5% given current valuations.
What return should I assume?
Long-run diversified portfolios have historically returned roughly 7% to 10% nominal. Being conservative is prudent: assuming 6% and being pleasantly surprised is far safer than assuming 10% and falling short with no time left to correct.
How does inflation affect my retirement number?
Substantially. At 3% inflation, purchasing power halves in about 24 years. The real value output shows your projected balance in today's money — that figure, not the nominal one, is what your spending should be planned against.
Am I saving enough?
A frequent rule of thumb is 15% of gross income including any employer match. The more reliable test is the one this calculator performs: does the projected sustainable income cover your expected expenses?
What is sequence of returns risk?
The risk that poor market returns arrive early in retirement, forcing withdrawals from a shrinking portfolio and permanently impairing it. Two retirees with identical average returns can have very different outcomes based purely on the order those returns arrived.
Should I include Social Security?
This engine does not model it. Social Security or a state pension will typically reduce the income your portfolio must supply, so treat the sustainable income here as the private-savings component of a larger total.
What if I retire early?
Early retirement compounds two problems: fewer contributing years and more withdrawal years. Most planners recommend a lower withdrawal rate — often 3% to 3.5% — for retirements expected to exceed 30 years.
Does this account for taxes?
No. Withdrawals from traditional 401(k) and IRA accounts are taxed as ordinary income, while Roth withdrawals are generally tax-free in retirement. Your after-tax income will differ depending on the mix of account types you hold.
How often should I revisit this projection?
At least annually, and after any major change in income, expenses or market conditions. A long-range projection is a planning baseline to be corrected repeatedly, never a one-time answer.
What if my employer matches contributions?
Include the match in the monthly contribution figure — it is part of what actually goes into the account. An employer match is an immediate guaranteed return and should generally be captured in full before any other investing.
Should contributions increase over time?
Ideally yes, at least with inflation. This engine models a level contribution, so if you plan to escalate them, re-run the projection periodically with your updated figure rather than trying to average it.
Is this retirement calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.
Which currency does it use?
Amounts display in US$ accounting format, but the underlying mathematics is currency-agnostic. The result is identical in any currency, so simply read the figures in your own.
Why does a result show an em-dash?
An em-dash indicates the calculation is not defined for the inputs given — typically a division by zero or a value outside the valid domain. We show a dash rather than a misleading number.
How do I report an error?
Email apexconverter.praxiscalc@gmail.com with the tool URL, your exact inputs, the output received and the output you expected. Verified mathematical errors are patched within 72 hours.