Use this free compound interest calculator to see how your money grows over time. Enter your principal, interest rate, compounding frequency, and an optional monthly contribution to see your final value, total interest earned, and year-by-year growth.
| Year | Balance | Interest Earned |
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Compound interest is interest earned on both your original principal and on the interest already accumulated. Unlike simple interest, which only ever applies to the principal, compounding creates a snowball effect: each period\'s interest joins the principal and earns interest itself. Over time, this produces exponential rather than linear growth.
Two levers make compounding powerful: time and frequency. The longer the money compounds, the more dramatic the curve becomes — most of the growth happens in the later years. More frequent compounding (daily vs annually) also increases the final amount, though the effect is smaller than people expect. Adding regular contributions turns compounding into a genuine wealth- or reserve-building engine, which is why it matters for both personal savings and business cash reserves.
A = P × (1 + r÷n)^(n×t)P = principal, r = annual rate, n = compounds per year, t = years
$10,000 at 6% compounded monthly for 10 years (no contributions):
Compounding is not just for personal savings. It shapes how business cash reserves grow, how debt balances balloon if unpaid, and how reinvested profits build value over time. Understanding the math helps you decide where to park reserves, how aggressively to pay down compounding debt, and how reinvestment compounds into long-term growth.
If you want help deciding how to deploy your business\'s cash — reserves, debt paydown, or reinvestment — our fractional CFOs can model the trade-offs against your specific situation. That is the kind of decision a free call can clarify quickly.
Our Ex-PwC Chartered Accountants help US startups and small businesses turn calculations like this into real financial strategy — pricing, cash flow, fundraising, and growth decisions.
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