Investment Calculator
See what a starting balance and a monthly habit turn into over time. This is the same compound-growth engine that powers projections inside the WealthTrunk app.
For illustrative purposes only. Not financial, tax, or investment advice.
Real return after inflation: 4.4%. Results are shown in today's money. Set inflation to 0% for future dollars.
How much you raise your monthly amount each year above baseline inflation.
A projection is only as good as your real numbers. WealthTrunk tracks every account you own, projects them together, and shows your whole net worth in one place.
Try the appHow this calculator works
Growth is applied monthly
Your annual return is converted to a monthly rate — (1 + rate)1/12 − 1 — and applied to the whole balance each month. Compounding monthly rather than annually is what the app does, so the two agree.
Contributions land after growth
Each month's contribution is added after that month's growth is applied, so a fresh contribution doesn't earn a return in the month it arrives. It's the conservative convention.
Contributions can escalate
If you set a contribution increase, the monthly amount rises by that percentage every year and compounds. A 3% increase roughly tracks saving a constant share of a salary that rises with inflation.
The split is what matters
The two stat cards separate what you put in from what the market added. Over long periods the growth typically overtakes the contributions — the crossover point is the interesting part.
Investment calculator FAQ
How is the growth calculated?
Month by month. Each month your balance grows by one month's worth of your annual return — (1 + rate)^(1/12) − 1 — and then your contribution is added. That's the same order the WealthTrunk app uses, so the projection here matches what you'll see in the app for the same inputs.
Are the results adjusted for inflation?
Yes. The inflation slider converts your nominal return into a real return using the Fisher equation — real = (1 + nominal) ÷ (1 + inflation) − 1 — and the projection compounds at that real rate. A 10% return with 2.5% inflation compounds at roughly 7.3%, so the balance is in today's purchasing power. Set inflation to 0% to see future dollars instead.
What does the contribution growth setting do?
It raises your monthly contribution every year by the percentage you choose, on top of inflation. Because the projection is shown in today's money, leaving it at 0% already assumes you increase your contribution enough to keep its buying power — so 2% here models a real raise of 2% a year beyond that.
What return should I use?
That's your call, and it's the assumption that moves the result most. Historical long-run stock market returns have averaged in the 7–10% range before inflation, but any individual decade can be far higher or lower. Try a few rates to see how wide the range of outcomes is.
What does the dashed line show?
Your contributions alone, with no growth applied — your starting balance plus every dollar you put in. The gap between the two lines is the compounding.
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