Free investment calculators are everywhere — so why use another one? Because most of them are black boxes: you type numbers, they hand you a result, and you have no idea how it was computed — or whether your data was quietly collected while you did it.
Caspenda works the other way. Every formula is published, everything runs in your browser, and nothing you type is ever stored. Here are five concrete things that actually give you.
1. Know your number — work backwards from any goal
Most people don’t start with “how much should I invest?” — they start with “I want to be comfortable.” The Savings Goal calculator inverts the question: tell it what you’re aiming for ($250k, $500k, $1M), your starting balance, time horizon and expected return, and it tells you the exact monthly contribution required. No guesswork, no “invest as much as you can” — a number you can actually act on. See how the math works in our guide to saving each month to reach a goal.
2. See where your money really comes from
Compounding is usually shown as one big number — which hides the most important insight: how much of your final balance came from what you saved, and how much from growth. The Compound Interest calculator splits the two. The Portfolio Growth calculator goes further, breaking your outcome into your contributions, investment growth, and the dollars lost to fees — so you see exactly where every dollar comes from, not just what it adds up to. Start with compound interest, explained if you want the underlying idea first.
3. Make smarter timing and cost decisions
Should you invest all at once or spread it out? The DCA vs Lump Sum calculator runs both under the same budget and time horizon so you can see the difference in plain numbers — and it’s honest about its limits: it uses a constant return to isolate the math, while real markets fluctuate. The Portfolio Growth calculator also shows the true dollar cost of fees over 20–30 years — a 0.5% fee quietly removes tens of thousands of dollars from a long-term balance, as we show in detail here.
4. Stay honest about inflation
A $1,000,000 balance in 2046 is not $1,000,000 in today’s money. Every Caspenda calculator that shows a future amount lets you check “Adjust for inflation” to see the result in today’s purchasing power. It’s the difference between a number that looks impressive and a number that tells you the truth about what you’ll actually be able to buy. The Inflation calculator shows it directly — and this look at what $100,000 will be worth in 20 years makes the point with real numbers.
5. Your numbers stay yours
Here’s the promise most calculator sites won’t make: no account, no email capture, no tracking scripts, and no data stored. Everything is calculated locally in your browser. You type, you calculate, you leave — and nothing you entered was ever sent anywhere. In an industry where the default is “input → tracking → signup”, that’s not a feature. It’s a principle. Read more about what Caspenda is and our privacy policy.
Try it in under a minute
Open any calculator, type your numbers, and the result appears instantly — with the formula and assumptions right below it. That’s the whole experience: transparent, private, and free. Start with the Compound Interest Calculator and see how your money grows.