See how a starting balance and monthly contributions grow over time.
Starting point
$
$
Growth assumptions
%
years
Projected outcome
Future value
$0
Total interest earned
$0
Total contributed$0
Of which, initial amount$0
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Choosing a return assumption
The default 7% reflects the S&P 500's long-run average after inflation (the index has returned closer to 10% per year nominally over the long term, but inflation eats a few points of that). A high-yield savings account or CD is a much lower but far more predictable 4–5% today. There's no "correct" number here — it's a long-term average, and any single year can vary wildly in either direction.
Common questions
What does "compounding frequency" actually change?
More frequent compounding means interest is calculated and added to your balance more often, so it starts earning its own interest sooner. The difference between monthly and annual compounding is real but modest — a bigger contribution or a longer time horizon matters far more to your outcome.
Is a 7% return guaranteed?
No. This is a planning estimate based on long-run historical averages for a diversified stock index. Actual returns are never smooth — some years are sharply negative, others far above average — and past performance never guarantees future results.
Why does starting early matter so much?
Compound growth is exponential, not linear. Money invested in your 20s has decades to compound, so it typically ends up contributing far more to your final balance than the same dollar amount invested a decade later — try changing the time horizon here to see the effect directly.