Future Value Calculator

Future value is the central question of long-term investing: what will my money be worth if I let it grow? The answer depends on three forces — the starting amount, the return rate, and time — but regular contributions turn a modest portfolio into a substantial one through compounding. This calculator handles both a one-time lump sum and ongoing monthly additions simultaneously, letting you model a realistic scenario like funding a retirement account or college fund. Choose monthly, quarterly, or annual compounding to match your investment vehicle, and the calculator shows your projected future value, total amount invested, and how much of the growth came from compound returns rather than direct contributions.

Two formulas are combined. FV of principal: P × (1 + r/n)^(n×t), where P is the starting balance, r is the annual rate as a decimal, n is the compounding frequency, and t is years. FV of contributions: PMT_period × ((1 + r/n)^(n×t) − 1) / (r/n), where PMT_period converts the monthly contribution to per-period by multiplying by 12 then dividing by n. For example, a $200 monthly contribution with quarterly compounding becomes $600 per period. The two future values are summed. When rate is zero, contributions grow linearly without compounding. Total invested = principal + (monthly contribution × 12 × years). Total growth = future value − total invested.