The questions that come up most about how Future Worth calculates its numbers, and what they actually mean.
A free calculator that compares buying something — a car, a house, a subscription, or anything else — against investing that same money in the market instead. It shows what the item ends up being worth over time, side by side with what your money could have grown into if invested, in plain numbers and plain English.
No. Future Worth is an illustrative tool meant to help you think through a decision more clearly — not to tell you what to do with your money. For anything with real financial stakes, talk to a licensed financial advisor.
It's the gap between what your money could be worth if invested, and what you'd actually have from the purchase itself — both measured in today's dollars, so it's a fair comparison. If a $40,000 car would be worth $3,200 in 30 years, but that $40,000 invested instead would be worth $287,000 in today's dollars, the opportunity cost of buying is roughly the difference between those two numbers.
Two different reasons, depending on your inputs:
First, over short timeframes or with a low market return, investing genuinely might not have grown enough yet to beat the alternative — the tool shows the real, unrounded result rather than pretending a gain exists when there isn't one.
Second, this tool deliberately floors the figure at zero and never displays a negative number, even in extreme edge cases where the underlying math could technically favor buying (for example, a fast-appreciating house against a very low market return). That's a simplification we chose on purpose, to keep the result easy to read — see the How It Works page for the full explanation.
Nominal is the raw number that would actually appear on a future account statement — no inflation adjustment. Today's dollars (also called "real") takes that same number and discounts it by your inflation assumption, showing what it's actually worth in today's purchasing power. A dollar in 30 years won't buy what a dollar buys today, so the "today's dollars" figure is the more honest one for comparing decisions.
Roughly 15% of the car's value is assumed to be lost each year, floored at 8% of the original price so an old car is never modeled as worth literally nothing. It's a simplified average — your specific vehicle and local market can differ.
Using the same standard amortization formula every bank and mortgage lender uses — based on the amount financed, the interest rate, and the loan term. Full formula on the How It Works page.
Because the model assumes real discipline: whatever you'd save (a lump sum and/or a monthly amount) is invested and never touched — it's never redirected to actually fund the purchase. If your savings compound for years before you buy, and continue compounding afterward too, the total can end up well ahead of buying right away. It's a best-case scenario, not a guarantee.
No. Every number you type in stays in your own browser and disappears when you close or refresh the page. There's no account, no server-side storage, and no personal information required to use the tool. See the full Privacy Policy.
Yes, completely — no sign-up, no paywall, no limits on how many times you can use it.
The default 10% market return reflects the S&P 500's long-run historical average annual return before inflation. The default 3% inflation rate is a commonly used long-run average. Both are fully editable — the defaults are a reasonable starting point, not a prediction of future performance.
Down payment can be entered as either a dollar amount or a percentage — editing one updates the other automatically, using the current purchase price. If you're seeing something that looks off, try refreshing the page — every field recalculates live as you type.