Key takeaway
ROI hides time and CAGR reveals it, so annualize before comparing any two investments.
Key takeaway
ROI tells you the total gain or loss on an investment as a percentage; CAGR tells you the smooth yearly rate that produced it. ROI hides the time it took; CAGR reveals it. Use both and you stop comparing a one-year win to a ten-year win.
ROI is the score; CAGR is the pace
Return on Investment (ROI) is the simplest measure:
ROI = (gain − cost) ÷ cost × 100
Put in $1,000, get out $1,300, and your ROI is 30%. Clean, but silent on time. A 30% ROI in one month is spectacular; in ten years it is mediocre. That silence is ROI's flaw.
Compound Annual Growth Rate (CAGR) fixes it by spreading the return evenly across the years:
CAGR = (ending value ÷ starting value)^(1 / years) − 1
It answers: "what steady yearly rate would get me from start to finish?" That makes different investments comparable.
A worked example
You invest $10,000 and it grows to $16,105 over five years.
- ROI = ($16,105 − $10,000) ÷ $10,000 = 61% total.
- CAGR = ($16,105 ÷ $10,000)^(1/5) − 1 ≈ 10% per year.
Now compare: Investment A returns 61% over 5 years (10% CAGR). Investment B returns 30% over 1 year (30% CAGR). ROI alone makes A look better (61% > 30%), but B grew far faster per year. CAGR tells the truth the ROI hides.
The ROI Calculator gives the total return; the CAGR Calculator annualizes it so you can compare across holding periods.
The mistake everyone makes: comparing ROIs across different time spans
A common error is ranking investments by ROI without checking the years. A 50% ROI over a decade is about 4.1% a year—barely ahead of inflation. A 20% ROI over one year is 20% a year. Side by side, the "smaller" ROI wins.
Other errors:
- Ignoring costs and taxes: ROI should use what you actually keep, not the headline gain.
- Treating CAGR as a guarantee: it smooths bumps; real years were up and down.
- Forgetting the start point: CAGR is sensitive to a particularly high or low starting value.
- Mixing it with yield: dividends are part of return but are not the same as price growth.
How to read returns
- Compute ROI for the total gain on a deal—use the ROI Calculator.
- Annualize with CAGR before comparing to anything held a different length—use the CAGR Calculator.
- Subtract costs and taxes so the comparison is real, not paper.
- Compare like periods: only line up CAGRs, never raw ROIs.
- Check the risk: a high CAGR from a wild ride is not the same as a steady one.
Related next steps
Find the total return with the ROI Calculator and annualize it with the CAGR Calculator. To project a steady rate compounding over time, the Compound Interest Calculator shows the buildup, and the Investment Growth Calculator models a plan.