Retirement calculator with Social Security and pensions
Guide · By Kevin Lan · Updated September 2026
Social Security and pensions don't start on day one, so they change your plan in a specific way: once that income begins, your portfolio only has to cover the gap — which can move your retirement date earlier.
Why the timing matters
Social Security and most pensions begin years after an early retirement, so they only offset your expenses from their start year onward. Before then, your portfolio carries the full load; after, it carries what's left. A calculator that simply subtracts Social Security from your expenses gets the early — and most demanding — years wrong.
Time-phased income is the accurate way
The correct approach models each income stream with a start year and an amount, and reduces the required withdrawal only from that year forward. Because the portfolio no longer has to fund those later years alone, your FIRE number can fall and your date can move sooner — often meaningfully, since later income is exactly what a long retirement leans on.
Approximating it yourself
Without time-phased inputs you can still get close: plan primarily for the bridge — the portfolio-only years between retiring and the year your Social Security or pension starts — and treat later income as a cushion. It's a rougher estimate; a model that phases the income in by year is more precise.
Add it in the app
The calculator below sizes your FIRE number and date from your investments for free. The iPhone app's pension and Social Security planning is time-phased — each stream starts in the year you choose — so the projection reflects income that arrives later.
FIRE calculator
Runs in your browser — nothing is sent anywhere.
Frequently asked questions
Should I include Social Security in a FIRE plan?
Yes, but phased in at its start age rather than assumed from day one. For an early retirement, the demanding years are before Social Security begins; modeling it from the correct year keeps those years honest and can lower the total you need.
How does Social Security change my FIRE number?
It reduces the spending your portfolio must cover from the year it starts, so the portfolio needs to fund mainly the bridge years plus any remaining gap afterward. That can lower your FIRE number and pull your retirement date earlier.
When does Social Security start?
In the U.S. you can claim reduced benefits as early as 62, full benefits at your full retirement age (67 for those born in 1960 or later), and the maximum by delaying to 70. A pension's start age is set by its plan.
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Find your date, then count down to it
See your number free above, then put the countdown on your iPhone home screen.