Compound Interest Calculator

Most compound interest calculators ask you to type in an annual return rate. That's a guess that wildly affects the projection. Ours pulls the real 5-year CAGR for any of 70+ assets — Apple, Bitcoin, S&P 500, gold, GBP/USD — straight from Yahoo Finance. We also compare against M2 money supply growth, which we haven't found on any other compound interest calculator. Free, no signup, no email.

M2 is the broadest commonly-tracked measure of money supply: physical cash, checking deposits, savings deposits, and money market funds. Globally it has grown roughly 7% per year over the past 25 years (faster post-2020). If your investment grows at less than M2, your money is losing wealth in real terms even when the nominal balance rises. The M2 comparison answers a single question: am I actually building wealth, or just keeping pace with money printing?

We pull the asset's closing price 5 years ago and today from Yahoo Finance, and compute the compound annual growth rate that gets you from one to the other. Five years captures roughly one full market cycle without overweighting decades-old bull runs. The number is cached briefly to keep the calculator responsive.

Five years is roughly one full market cycle (bull → correction → recovery), so it captures both upside and downside without overweighting decades-old conditions that may not apply now (zero interest rates, no internet, different inflation regime). Shorter windows (1-3 years) are too noisy and can be dominated by a single rally or crash. Longer windows (10+ years) drag in conditions that may no longer be relevant. Five years is the balance most professional analysts use.

A little. Daily vs. annual compounding at 10% per year over 30 years differs by about 6% in the final number — meaningful but not life-changing. Most stocks and crypto effectively compound continuously, so daily is the most realistic setting. Bonds and savings accounts typically compound monthly or quarterly.

Any projection that long is a rough sketch, not a forecast. Markets, currencies, and even asset classes can change beyond recognition over decades. Use the calculator to run scenarios at the bookends — pessimistic 4%, realistic 7-8%, optimistic 10%+ — and plan around the range, not a single number. The further out the horizon, the wider the range you should treat as plausible.

No calculator can. Past returns don't predict the future. What our 5-year CAGR gives you is a much better starting estimate than guessing a number out of thin air. For long horizons, run multiple scenarios — pessimistic, realistic, optimistic — to see the range. The point of the calculator is not certainty; it's framing.

No — the projection is gross, before any capital gains or dividend tax. Tax depends heavily on your jurisdiction and account type (taxable vs. ISA / Roth / SIPP / TFSA / equivalent shelter). For an after-tax estimate, run the result through our Capital Gains Tax calculator with the appropriate jurisdiction selected, or assume a 10-25% drag depending on your tax bracket and how often you realise gains.