Calculate how many years remain until your target retirement age

Why the time-to-retirement number matters more than the age

Most retirement planning conversations fixate on the retirement age — 60, 65, 67, early, late. The useful number is actually the years remaining, because that is the variable your contributions and compounding act on. Two 40-year-olds targeting retirement at 65 have 25 years of runway, but a 40-year-old targeting 55 has only 15 — enough of a difference that the required savings rate roughly doubles. Framing the question as years-remaining rather than age-targeted reorients planning around the lever you can actually move.

How the math works

Years to retirement = target age − current age. That is the trivial part. The more interesting output is the projection: Balance at retirement = current savings × (1 + r)^n + monthly × ((1 + r/12)^(12n) − 1) / (r/12), where r is the annual return rate and n is years. The tool runs both calculations so you can see the time horizon and what it compounds to given your current savings pace.

Why the last 10 years contribute disproportionately

Compound returns are back-loaded. On a 30-year horizon at 7% annual return, roughly 60-65% of the final balance accumulates in the last 10 years. This is the geometric reality of compounding, and it has two implications. First, extending your career by even a few years late in life can add substantial balance because each year is working on the largest base. Second, a market crash in the final 5 years can erase a material share of a portfolio that looked comfortable a decade earlier — sequence-of-returns risk is highest near retirement, which is why many planners recommend a glidepath into more conservative allocations in the final decade.

What the calculator ignores

Several variables the tool does not model: inflation (the real spending power of the future balance is less than the nominal number), variable returns (a single expected return understates the range of possible outcomes), tax treatment of different account types (retirement accounts compound differently than taxable accounts), and contribution escalation (if your contributions grow with income, final balances can be dramatically higher than flat-contribution projections). Use the result as a direction and rough magnitude, not a forecast.

How to interpret the gap

If the projected balance is well below what the retirement would need to be funded, three levers adjust it: contribute more monthly, extend the working years, or accept a smaller retirement spend. The first two compound the result meaningfully over long horizons. The third is what most households end up doing implicitly through decisions like downsizing, relocating, or working part-time past the nominal retirement age. None of these is failure — most retirement plans require adjustment as real returns and life events diverge from the 25-year-old's spreadsheet.