This future value calculator projects growth three ways: a lump sum invested today, a stream of monthly deposits, or both together — the forward-looking twin of present value.
Monthly deposits compound monthly; the lump sum rides the same monthly clock here so both streams are comparable. Inflation is not deducted — at 3% inflation, divide the result by (1.03)^years mentally for today’s-dollar terms, or run the reverse trip on our Present Value Calculator.
The Two Engines of Growth
A lump sum grows as PV × (1+r)^t — compounding on everything, every period. A deposit stream grows as an annuity: PMT × ((1+r)^n − 1) ÷ r — each deposit compounds for whatever time it personally has left, which is why early deposits outweigh later ones so dramatically. The comparison that sells investing: in the example below, the depositor puts in 4.8× the lump sum’s money yet ends with a portfolio where the growth is the largest slice. Time in the market is the input no one can buy later. The lump-sum-only view with a savings-account flavor is our Savings Calculator. Part of our Finance Calculators collection.
Worked Examples (Verified)
- Lump only: $10,000 at 7% for 20 years (annual compounding) = $38,697 — the money nearly quadruples without a single addition
- Deposits only: $200/month at 7% for 20 years: you contribute $48,000 and end with ≈ $104,185 — growth contributed $56,185, more than you did
- The defaults together land around $144,600: check the Growth card — by year 20 the portfolio earns more each year than the $2,400 you deposit into it
- The cost of waiting 5 years: the deposits-only plan started 5 years later reaches only ≈ $63,400 by the same end date — a ~$40,800 tuition for procrastination, on just $12,000 of skipped deposits
Assumptions to Argue With
- Smooth returns are fiction: real markets deliver the average in lumpy, sometimes terrifying order. The projection is a planning scaffold, not a promise.
- Fees and taxes skim the rate: a 1% annual fee on the combined default plan costs roughly $19,000 of the ending value. Run the rate 1% lower to see your own fee drag.
- Inflation: 7% nominal at 3% inflation is 4% real — halve the horizon’s drama accordingly when planning in today’s dollars.
Related Tools
- Present Value Calculator — the reverse direction
- Savings Goal Calculator — deposits needed for a target
- Finance Calculators — the full collection
Frequently Asked Questions
What is future value?
What a sum or stream of payments will be worth at a future date given a growth rate. FV = PV × (1+r)^t for a lump sum; deposits add the annuity term PMT × ((1+r)^n − 1)/r.
How much will $10,000 grow to in 20 years at 7%?
$38,697 with annual compounding — the Rule of 72 sanity-checks it: money doubles about every 10.3 years at 7%, so two doublings ≈ $40,000, and compounding details trim it slightly.
Is it better to invest a lump sum or monthly?
Mathematically, lump-sum-now wins whenever the money exists (more time compounding — historically about two-thirds of periods). Monthly investing wins psychologically and when the money arrives monthly, which for most humans is the actual constraint.
What return should I assume?
Long-run US stock market nominal returns have averaged ~10% (about 7% after inflation); balanced portfolios less; savings accounts are printed on your statement. Conservative planning uses 5–7% nominal for diversified portfolios — and stress-tests at less.
Does this calculator include inflation?
No — results are nominal (future dollars). For today’s-dollar terms, either lower the return by your inflation assumption (7% − 3% = 4% real) or discount the answer with the Present Value Calculator.
Is this future value calculator free?
Yes — free, instant, no sign-up.