Investment Calculator
Project your investment growth, or solve for the contribution, rate, starting amount, or time needed to reach a goal.
About this calculator
Project how a starting amount and regular contributions grow under compound interest — or flip it around and solve for the contribution, return rate, starting amount, or time needed to hit a savings goal.
Most investment calculators only run in one direction: enter your numbers, get an end amount. This one has five tabs so you can solve for whichever variable you don't know yet. "End Amount" works forward like a typical projection. The other four tabs work backward from a goal: "Additional Contribution" tells you how much you'd need to add regularly, "Return Rate" tells you what growth rate you'd need, "Starting Amount" tells you what lump sum you'd need today, and "Investment Length" tells you how long it would take — all to reach the same target End Amount.
How to use
- Choose a tab for the value you want to solve for — the other four become your known inputs.
- Enter your starting amount, investment length, return rate, and compounding frequency as applicable.
- Enter an additional contribution amount, and whether it's contributed monthly or yearly, at the beginning or end of each period.
- On any tab other than "End Amount", enter your target End Amount goal instead.
- Press Calculate to see the solved value, the balance breakdown, and the full accumulation schedule.
Tips
- More frequent compounding (e.g. daily vs. annually) grows a balance slightly faster for the same nominal rate.
Formula
Future Value = Starting Amount × (1 + i)ⁿ + Contribution × [(1 + i)ⁿ − 1] / i
where i = the periodic growth rate implied by the compounding frequency, n = number of periods
The "Return Rate" and "Investment Length" tabs solve this in reverse using bisection; "Additional Contribution" and "Starting Amount" solve it directly since both terms are linear.