Coast number calculator
There is a balance that reaches your target on its own, without another dollar added. Knowing where it sits changes how the next ten years feel.
Your coast number
$341,307
Reach this and it grows to $1,200,000 by 65 with no further contributions.
If you stopped contributing today
$632,862
what $180,000 becomes over 33 years
You are $161,307 short of coasting. At $1,000 a month you reach the coast point in about 18.9 years — at age 51.
This uses a real return — nominal minus inflation — so the target stays in today’s dollars. It assumes steady returns, which no market delivers, and ignores taxes and fees. A coast number is a milestone worth knowing, not a plan on its own.
What a coast number is
It is the amount that, left completely alone, compounds to your retirement target by the age you pick. Reach it and further contributions stop being required — the target is already funded by time.
This is not the same as retiring. You still work, still earn, still pay for your life. What changes is that money going into retirement accounts becomes a choice rather than a necessity.
Why it arrives earlier than the full number
The coast number is much smaller than the target, and the gap is entirely time. Money invested at 32 has three decades to compound; money invested at 60 has almost none. That is the same back-loading that makes compounding feel slow early on — read from the other direction.
Which is why the coast point can arrive surprisingly early for someone who started young, and why starting late is expensive in a way that no amount of later intensity fully fixes.
Why this uses a real return
The calculator subtracts inflation from the nominal return and works in today’s dollars. A target of a million in forty years does not buy what a million buys now, and a projection that ignores that is quietly flattering.
Using a real return means the target you type is what it appears to be: purchasing power in money you understand today.
What reaching it actually lets you do
The useful part is not stopping. It is that the option exists:
- Take work that pays less but suits you better.
- Drop to four days, or take a long break, without derailing anything.
- Redirect saving toward something nearer — a house, education, a business.
- Absorb a layoff without it becoming a crisis.
Most people who reach a coast number keep contributing anyway, and that is fine. Knowing you do not have to is worth something on its own.
The honest caveats
It assumes a steady real return, which no market delivers — the sequence of returns matters enormously, as the withdrawal stress test shows. It ignores taxes and fees. And it rests on a target figure that is itself a guess about a life you have not lived yet.
Treat it as a milestone worth knowing rather than a finish line to plan around. Recalculate it occasionally, because the inputs change.
Related: the point where saving becomes optional
Educational only. This explains how these products and accounts work in general. It is not financial, tax, or legal advice, and not a recommendation to buy anything. Your situation is specific to you — check with a licensed professional before acting.