Combine a starting lump sum with an optional monthly contribution to see your projected balance, total contributed, and total growth.
Future value (FV) is what a sum of money today — plus any regular contributions you add along the way — grows to by a future date, once you apply an assumed annual rate of return and let compounding work over the full period. It's the mirror image of present value, which instead discounts a future amount back to today; see the Present Value Calculator, a companion tool, for that direction.
A lump sum alone only compounds on the money you start with. Regular monthly contributions add fresh principal every month, and each new contribution then gets its own remaining years to compound. Over long horizons this matters a lot — consistent contributions can end up producing more total growth than the original lump sum did, especially when the lump sum is modest relative to the monthly amount and the time horizon is long.
There's no guaranteed number to plug in. A diversified stock/bond portfolio has historically returned roughly 5-8% annually over long multi-decade periods (before inflation and fees), while a savings account or CD might return far less but with far less risk. It's worth running the calculator at a few different rates — say 5%, 7%, and 9% — to see how sensitive your final number actually is to the assumption, rather than anchoring on a single optimistic figure.
The underlying math is functionally the same — both grow a starting principal plus periodic contributions at a compounding rate. This tool is framed around total future value and splits the result into total contributed vs. total growth; the Compound Interest Calculator presents a similar breakdown with its own layout, so it's worth comparing both if you want to double-check a number or prefer one tool's presentation over the other.
Worked example: starting with a $10,000 lump sum, contributing $200/month, at a 7% annual return for 20 years: future value comes out to roughly $144,572.72. Total contributed over that time is $10,000 + ($200 × 240 months) = $58,000.00, meaning growth alone accounts for the remaining $86,572.72 — nearly 60% of the final balance came purely from compounding, not from money you put in.