Written by Sarah Mitchell · Reviewed by Alex Chen · August 1, 2026
Project the future value of your investments with compound interest and regular contributions.
Enter your investment details and click Calculate.
Feed it four numbers — a starting lump sum, a monthly contribution, an expected annual return, and a holding period in years — and it projects what the pot would be worth at the end if that return arrived steadily every year. It suits someone comparing savings plans, a parent rough-sizing a college fund, or anyone who wants to see what time alone does to a fixed deposit. Everything runs in the browser: no account, no upload, nothing leaves the page.
The core engine is the compound interest formula FV = P(1 + r/n)nt, where P is the starting balance, r is the annual rate written as a decimal (8% becomes 0.08), n is how many times a year interest gets credited, and t is the number of years. The monthly contribution field rides the same schedule: instead of sitting as a flat pile, each deposit grows under the same compounding path, which is why the contribution term matters more over long horizons.
The frequency dropdown maps n to a real calendar: 12 for monthly, 4 for quarterly, 2 for semi-annual, 1 for annual. That choice is not cosmetic — it changes how early interest starts earning its own interest, and the results table separates what you put in from what the account produced on its own.
Start with $10,000, add nothing each month, expect 7% per year, and hold for 20 years with annual crediting. Plug the values into the formula: FV = 10,000 × (1 + 0.07/1)1 × 20 = 10,000 × 1.0720. Raising 1.07 to the 20th power gives 3.8697, so the projection lands at $38,696.84. Of that total, $28,696.84 is interest — the original $10,000 produced nearly three times itself with no extra deposits.
Switch the dropdown to monthly compounding and the identical inputs return $40,387.39. Nothing changed except how often interest is credited, yet the balance is about 4.4% higher, which is the cleanest demonstration on this page of what the frequency setting actually buys.
The output is nominal: it ignores inflation, taxes, and account fees, and it assumes one fixed rate for the entire holding period. Markets do not pay a constant 7%; the projection is a straight line drawn through a bumpy road, so read it as a planning range, not a promise. The tool refuses to calculate when the rate is zero or negative, or when the starting amount is negative, because the formula quietly produces nonsense in those cases. The answer is also only as honest as the expected return you type in — an assumption, not a guarantee.
Interest credited monthly begins earning on itself sooner than interest credited annually. The gap looks small over a few years and widens with the period. On $10,000 at 8% over 10 years with no deposits, annual crediting yields $21,589.25, quarterly yields $22,080.40, and monthly yields $22,196.40.
Yes. The monthly contribution is grown along the same compounding schedule rather than added as a flat total, and the results panel splits the future value into the contributions you made versus the interest the account earned on top of them.
No. The result is the nominal balance — not its purchasing power, and not what you would keep after the tax authority takes a share of taxable gains. For a rough real-world figure, subtract your expected inflation rate from the annual return before entering it; for tax-aware planning, use an account-appropriate rate instead.
The tool refuses to calculate. A zero or negative rate is treated as invalid input, and the results panel asks for valid details rather than printing a number that looks plausible but means nothing.
Each row shows the balance at the start of the year, the deposits made during it, and the interest earned that year. Later rows out-earn early ones because they compound a larger base — the table is the visual proof of why holding periods matter more than timing.
Use it when comparing scenarios — larger contributions versus a longer horizon, or one crediting frequency versus another — because it isolates a single variable cleanly. Skip it when the decision hinges on taxes, inflation, fees, or the order in which bad years arrive, since none of those are modeled. And keep it away from debt: loans and mortgages belong in the EMI calculator, which works the opposite direction. If a real purchase is on the line, take the rounded figure from this page to a financial planner rather than treating it as a commitment.