Orpheus

Compound Interest Calculator

What regular saving actually turns into, and how much of it is growth.

Inputs
$
$
6%
years
Compounds
Final balance
132,061.25$
Mostly yoursCompoundingGrowth-ledMostly growth
You put in
65,000.00$
Growth earned
67,061.25$
Growth as share of the total
50.8%
Contributions
240 monthly
A = P(1+i)ⁿ + C·((1+i)ⁿ − 1) ÷ i

Assumes a steady return and ignores tax, fees and inflation. Real returns vary year to year.

Every tool runs entirely in your browser. Your files are never uploaded to a server.

Compound interest earns returns on previous returns, so growth accelerates over time. This shows the final balance and splits it between what you put in and what compounding added, which is where the effect becomes obvious.

How to use the Compound Interest Calculator

  1. Enter what you start with. Zero is fine if you are starting from nothing.
  2. Add your monthly contribution. Regular contributions usually matter more than the starting amount over long periods.
  3. Set return, term and frequency. Then read the split between contributions and growth beneath the balance.

About compound interest

Compound interest is usually explained with a lump sum left alone for decades, which makes for a striking chart and describes almost nobody. Most people save gradually, and that changes the shape of the outcome: the first years are dominated by your own contributions, and growth only takes over once the balance is large enough for returns on it to exceed what you are adding. That crossover is the moment worth aiming for, and it arrives sooner with a higher rate but much more reliably with more time. The split shown here — what you put in versus what growth added — is deliberately more prominent than the headline balance, because it is the part that actually demonstrates the effect. Two caveats keep the number honest. Real returns are not steady; a portfolio averaging six percent will not deliver six percent each year, and the order of good and bad years matters when you are contributing throughout. And fees compound against you exactly as returns compound for you, so a one percent annual charge over thirty years costs far more than one percent of anything.

Frequently asked questions

What is the difference between simple and compound interest?
Simple interest is earned only on the original amount. Compound interest is earned on the balance including previous interest, so each period starts from a larger base and growth accelerates.
Does compounding frequency make much difference?
Less than most people expect. At 5% over ten years, monthly rather than annual compounding turns $1,000 into $1,647 rather than $1,629 — real, but far smaller than the effect of rate or time.
Why does the growth share rise so sharply later on?
Because returns compound on a balance that includes all previous returns. Early on the balance is mostly your own money; given enough years, growth can exceed everything you contributed.
Does this account for inflation, tax or fees?
No. It shows nominal growth. Subtract inflation for real purchasing power, and remember that fees are charged on the whole balance, so they compound against you the same way returns compound for you.

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