The most powerful wealth-building habit is not a big starting sum — it's a regular monthly contribution left to compound for years. This calculator combines both: a starting amount plus fixed monthly deposits, growing at your expected annual return.
Como funciona
Your starting principal compounds monthly, and each monthly contribution starts compounding from the month it's deposited. The calculator sums both streams and shows the future value, the total you actually put in, and the pure investment gain.
A fórmula
P is the starting amount, C the monthly contribution, i the monthly rate (annual ÷ 12), and n the number of months. The second term is the future value of an ordinary annuity.
Exemplo resolvido
5,000 to start, 300 per month, 7% annual return, 15 years: the future value is about 109,330. You contributed 59,000 in total (5,000 + 180×300) — meaning roughly 50,330, nearly half the final amount, is compound growth.
Perguntas frequentes
What annual return should I assume?
Broad stock-market index funds have historically averaged 7–10% per year over long periods before inflation, but past returns guarantee nothing. Running the calculator at 5%, 7%, and 9% gives you a realistic range instead of a single guess.
Which matters more — starting amount or monthly contribution?
Over long horizons, the contribution usually wins. In the example above, the 300 monthly deposits produce about 95,000 of the final value versus 14,000 from the initial 5,000.
Does this account for inflation or fees?
No — results are nominal. To think in today's purchasing power, subtract expected inflation from your return (7% return − 3% inflation → use 4%), and remember fund fees reduce returns one-for-one.