This is the simplest honest version of the retirement savings question: start where you are, add what you add each year, compound at your assumed net return, and see the year-by-year table. No hidden target math, no verdict — just the accumulation, fully auditable, so you can test what actually moves the number.
How this projection works
Each year, your balance grows by the net return you enter (expected return minus fund fees — do the subtraction yourself, honestly), and then your annual contribution is added. That's the entire model. The power is in repeating it for 20 or 30 years and watching the growth line overtake the contributions line.
Two levers dominate the outcome: the contribution amount and time. The return assumption matters too — drop it from 7% to 5% and the ending balance falls sharply — which is why you should plan on a range, not a point.
balance[n] = balance[n-1] × (1 + netReturn)
+ annualContributionIf you want a verdict on whether the ending number is enough, that's the next question — the retirement calculator layers your spending and a withdrawal rate on top of this same math.
The sample, end to end. You start with $50,000, add $12,000 a year for 20 years, and earn 7% net of fees. You end with $$685,430. You put in $240,000 — growth did the other $445,430. The crossover is the story: by year 20, growth has out-contributed you.
Terms & definitions
Net return
Annual return minus fund fees. The rate your balance actually compounds at — which is why the field asks you to subtract fees yourself.
Expense ratio
The annual fee a fund charges, as a percentage of assets. Charged against the whole balance every year.
Compounding
Growth earning growth. Over long horizons it out-earns contributions — the crossover the year-by-year table shows.
Cumulative contributions
Everything you put in, added up, ignoring growth. The baseline the balance must beat.
Frequently asked questions
Is this different from the retirement calculator?
Yes — by design. This page is pure accumulation: it projects what your savings become and stops. The retirement calculator starts where this one stops, comparing the projected balance against a spending-based target. If you just want to watch a number grow, you're in the right place; if you want the funded verdict, use that one.
What return should I use?
We default to 7% — roughly a blended long-run stock/bond average before fees. Enter it net: subtract your blended expense ratio first. And it is an assumption, not a prediction — stress-test by dropping it to 5% and watching the ending balance move.
Can I enter monthly contributions instead?
Multiply by 12 and enter the annual total — a $1,000 monthly contribution is $12,000 a year. The math compounds annually, so very large monthly amounts introduce small rounding differences; for planning purposes they're immaterial.
Does this account for raises or increasing contributions?
Not in this version — contributions stay flat in nominal dollars. If you expect steady raises, run the projection at your current contribution to see a floor, then again at your contribution five years from now to see the slope. Both numbers are more useful than one optimistic one.
References
- IRS — retirement topics and plan basics: irs.gov/retirement-plans
- Investor.gov — compound interest calculator and fundamentals: investor.gov
- U.S. Department of Labor — a look at 401(k) fees: dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/a-look-at-401k-plan-fees