Retirement Calculator — nest egg and the income it supports

How it works

Accumulation first: the nest egg is the starting balance grown at the pre-retirement return, plus the contribution stream accumulated by the savings-annuity formula — N = P(1+r)^y + d·((1+r/12)^(12y) − 1)/(r/12), over the years from your current age to retirement. Decumulation second: the nest egg becomes a payout annuity, and the sustainable monthly income is the level draw that exhausts it exactly at the end of the retirement years while the balance still earns the retirement return — the same amortization formula a loan uses, read from the other side. The outputs split the nest egg into what you contributed and what growth added; on a long horizon, growth is the larger share. The retirement-age sweep prices the single biggest lever: each extra year worked compounds the balance longer and funds fewer retirement years, so both figures climb steeply. This page is the general engine; its jurisdictional children price the specific vehicles — 401(k), IRA, Roth, RMDs, Social Security.

Worked example

Each phase rests on a published pair. Accumulation is the savings annuity: $300 a quarter at 5.75% for four years grows to $5,353.89 (LibreTexts §8.04) — the formula this page runs on your contributions. Decumulation is the amortization pair reversed: a $250,000 nest egg at 6% over 30 years supports $1,498.88 a month (LibreTexts §8.05, the published mortgage payment read as a withdrawal). On the default plan — age 35 to 67, $50,000 saved plus $500 a month at 7% — this calculator grows a nest egg near $1.15 million and, at a 4% retirement return over 25 years, supports about $6,070 a month: its own composition of the two published primitives.

Frequently asked questions

How much will I have saved by retirement?

The nest-egg output: your current balance compounded to retirement plus every contribution accumulated along the way. It grows with three levers — how much you start with, how much you add, and the return — and time amplifies all three, which is why starting at 25 versus 35 changes the result so much.

How much monthly income will my savings provide?

The sustainable-income output: the level monthly withdrawal that draws the nest egg to zero over your retirement years while the balance keeps earning. It is the same math as a loan payment, with you as the lender — so a bigger nest egg, a higher retirement return, or fewer retirement years each raise it.

Why does retiring a few years later help so much?

Two compounding effects at once: each extra working year lets the balance grow another year AND removes a year you have to fund. The sweep shows both — the gap between retiring at 62 and 67 is far larger than five years of contributions alone, because the last years before retirement are when the compounding is largest.

What return should I assume?

A pre-retirement return reflecting your investment mix and a usually more conservative retirement return, since portfolios often de-risk with age. Both are assumptions, not promises — the result scales sharply with them over decades, so run a cautious and an optimistic figure and treat the spread as the plan.

Does this include inflation, taxes, or Social Security?

No — the figures are pre-tax, in future dollars, and exclude Social Security. A nest egg in 30-year dollars buys less than the same number today; the investment calculator shows the real-terms view, and the Social Security calculator estimates that separate income stream to add on top.

How is this different from the 401(k) or IRA calculators?

They are this engine applied to specific vehicles with their statutory contribution limits and tax treatment; this page is the vehicle-agnostic projection. Use it for the whole-picture nest egg, and the account-specific pages to see how much each tax-advantaged vehicle can hold.

How accurate is this, and what does it exclude?

The two-phase math is exact for constant returns and level contributions. It excludes inflation, taxes, fees, variable returns and sequence-of-returns risk (a bad early-retirement market is harsher than the average implies), Social Security, pensions, and required minimum distributions. Treat it as a structural projection, not a guarantee.