Future Value Calculator
Calculate the future value of an investment with compound growth, initial lump sum, and optional monthly contributions.
About the Future Value Calculator
The future value of an investment answers a simple but powerful question: how much will my money be worth in the future if it grows at a given rate? This is the foundational concept behind compound interest — one of the most powerful forces in personal finance. Albert Einstein reportedly called compound interest the eighth wonder of the world, and the math bears that out: money that grows at 7% annually doubles approximately every 10 years.
Our future value calculator computes the projected value of an investment with three inputs: an initial lump sum, optional regular monthly contributions, and an assumed annual return rate. It compounds monthly (dividing the annual rate by 12), which is the most common compounding period for investment accounts. The year-by-year breakdown shows not just the final number but the trajectory of growth.
The return rate assumption is critical. A long-term stock market index fund has historically returned around 7% annually after inflation in the United States. A savings account might return 4–5% today but historically much less. Bonds return around 3–5%. Adjust the rate to match your expected investment vehicle and see how dramatically different rates compound over long horizons.
The Power of Compound Growth
Compound growth means that returns are calculated not just on the original principal but on the accumulated returns as well. A $10,000 investment at 7% earns $700 in year one. In year two, it earns 7% on $10,700 — that is $749. The extra $49 seems trivial, but compounding over 30 years turns $10,000 into over $76,000 without any additional contributions. Add $500 per month and the same $10,000 grows to over $650,000 over 30 years — illustrating how time, rate, and regular contributions interact to create wealth.
The Rule of 72 is a quick mental shortcut: divide 72 by your annual return rate to estimate how many years it takes for an investment to double. At 6%, money doubles every 12 years. At 9%, every 8 years. At 12%, every 6 years. This rule helps develop an intuition for how different rates translate to long-term outcomes without needing a calculator.
Two investors contribute the same total amount but at different stages of life. The early investor who contributes $5,000/year for 10 years starting at 25 — then stops — will typically end up with more at 65 than the late investor who contributes $5,000/year for 30 years starting at 35. This is the mathematical case for starting early: the first decade of compound growth is disproportionately valuable.