Retirement Calculator

How to Use the Retirement Calculator

1. Enter your current age - use your age in whole years. A 37-year-old checking on their 37th birthday gets the same projection as one checking six months later; the tool rounds to whole years.
2. Enter your retirement age - the age at which contributions stop and you expect to begin withdrawals. Full Social Security retirement age is 67 for anyone born in 1960 or later; early retirement at 62 cuts benefits by about 30%.
3. Enter current savings - the combined balance of everything earmarked for retirement: 401(k), 403(b), Thrift Savings Plan, traditional and Roth IRAs, HSA (if used as a stealth retirement account), and any taxable brokerage reserved for retirement.
4. Enter monthly contribution - everything you add each month, including employer match. If you contribute 10% of salary and your employer matches 5%, the combined monthly amount is the right figure.
5. Enter expected annual return - a long-term average. Seven percent is a common planning figure that represents roughly the S&P 500's real (inflation-adjusted) return over the past 50 years. Use 5% for a conservative plan, 9-10% for a more optimistic one.
6. Review the projection - the output shows projected retirement fund, total contributions, and total interest earned. Click "Show Year-by-Year Projection" for an annual table that lets you spot the inflection where compound growth outruns contributions.

The Math: Future Value of an Annuity Due Plus a Lump Sum

The projection combines two Time Value of Money formulas. The lump-sum piece grows your current balance: FV = PV × (1 + r)n. The contribution piece is the future value of an ordinary annuity: FV = PMT × ((1 + r)n - 1) / r, where PMT is the monthly contribution and r is the monthly rate (annual rate / 12). Adding the two produces total projected value. This is the same math taught in finance programs, used by Fidelity, Vanguard, and Empower retirement projections, and encoded in Excel as FV(rate, nper, pmt, pv).

The calculation runs as a Preact island that iterates month-by-month so it can produce the year-by-year table. Inputs use parseFloat; Math.pow handles exponentiation; output formatting goes through Intl.NumberFormat in USD. No contribution amount, current balance, or target age is transmitted - everything lives in component state and disappears on tab close. The math assumes contributions happen at the end of each month (ordinary annuity); switching to annuity-due (start of month) raises the projection by roughly one month of growth.

Who This Is For

• Someone in their 20s or 30s checking whether their current savings rate is on track, or whether they need to raise 401(k) contributions.
• A mid-career worker evaluating the impact of a raise - what happens to the 65-year-old number if the new monthly goes up by $500.
• A spouse building consensus with their partner about whether to retire together at 62 or one at 65 and one at 67.
• Someone comparing a pension-only employer with a no-pension employer that offers a 6% 401(k) match.
• A career-changer deciding whether a 2-3 year drop in income will meaningfully hurt long-term net worth (usually less than you fear).
• A parent modeling the cost of funding a 529 plan while simultaneously maxing retirement contributions.

Where Simple Projections Break Down

The largest simplification is the constant return rate. Real markets deliver sequences of returns - a couple of bad years early in retirement have much more damaging effects than the same years in the middle, a phenomenon called sequence-of-returns risk. A 7% expected return with a standard deviation of 15% (typical for a US equity-heavy portfolio) produces a wide distribution of outcomes; the median outcome is often far lower than the mean. Monte Carlo simulators in Fidelity Planner, Vanguard's Retirement Nest Egg, and free tools like FIRECalc address this by running thousands of simulated lifetime paths. The second simplification is that the projection is in nominal dollars: if you assume 7% returns and inflation runs 3%, the real purchasing power of the projection is roughly 3.9% growth, and $1 million at 65 buys what $411,987 buys today if you are 30 now. Contribution limits also change the plan: 401(k) contributions in 2024 max at $23,000 (plus $7,500 catch-up at 50+), IRA limits at $7,000 ($8,000 catch-up), and those limits rise roughly with inflation over time.

How People Actually Use Retirement Numbers

Two mental models dominate. The 4% rule (or "safe withdrawal rate"), drawn from the 1998 Trinity Study, says that a retiree withdrawing 4% of their starting balance each year, adjusted for inflation, has historically had a very high probability of not running out over a 30-year retirement. Twenty-five times your annual expenses is therefore the minimum "retirement number" - $50,000 annual spending implies $1.25 million saved. The second model is replacement income: target saving enough that your portfolio plus Social Security produces roughly 70-80% of your pre-retirement income. Both approaches matter: the 4% rule frames total net worth, while replacement income frames cash flow. This calculator produces the nominal portfolio value, which you can then compare against either target. Actual retirement planning requires accounting for Social Security (ssa.gov offers a personalized estimator), pensions, healthcare before Medicare eligibility at 65, Roth versus traditional tax treatment, state income tax in retirement residence, and required minimum distributions starting at 73 under the SECURE 2.0 Act.

How This Compares to Fidelity, Vanguard, and Personal Capital

Fidelity's Retirement Planner and Vanguard's Retirement Nest Egg are Monte Carlo simulators that produce probability-of-success percentages rather than single-point projections; they are more accurate for variable returns but require account linking or manual detail entry. Empower (Personal Capital) Retirement Planner pulls actual balances via Plaid and runs similar Monte Carlo, with the tradeoff of data sharing and advisor solicitation. NewRetirement and ProjectionLab are subscription tools with much finer-grained modeling (separate tax buckets, Social Security optimization, healthcare cost modeling). Excel's FV function reproduces this calculator's math directly. This tool's value is a quick estimate with zero account linking - useful when you want to see roughly where a contribution change lands before diving into a detailed planner. The result is informational and should not replace advice from a CFP, CPA, or fee-only fiduciary who can account for your full tax picture and specific account types.