Compound annual growth rate is the constant yearly rate that would take a starting value to an ending value over a period. It smooths volatile individual years into one comparable number, which makes it useful for comparing companies and misleading whenever the underlying path was erratic.
Why not just average the years
Because averaging overstates growth whenever results swing. A business that gains 100% then loses 50% has an arithmetic average of +25% a year and has actually gone nowhere. CAGR reports 0%, which is the truth.
Worked example
Revenue goes from $100M to $200M over five years.
CAGR = (200 ÷ 100)1/5 − 1
= 1.1487 − 1 = 14.9% a year
That single figure is now comparable against any other company over any other period, which is the entire point of the measure.
What it deliberately hides
CAGR describes only the first and last points. Everything between them is discarded. Two companies can report an identical 15% CAGR while one grew steadily every year and the other fell 40% then tripled. The second is a far riskier business and the number cannot tell you so.
The fix is simple and almost nobody does it: look at the individual years alongside the CAGR. If they cluster near the CAGR, the growth is structural. If they scatter, the CAGR is arithmetic rather than description.
The endpoint problem
Because only two points matter, choosing them decides the answer. A company can present a flattering CAGR by starting from a recession trough or ending on a record year, and neither choice is dishonest on its own.
Two defences. Run the calculation over several different windows and see whether the answer holds. And check whether the start or end year was unusual for the industry rather than for the company, since a cyclical trough makes everyone look like a compounder.
Where it is most useful
Comparing companies of different sizes, since a rate normalises for scale. Testing a management claim, since "we have doubled revenue" says nothing without a period attached. And checking whether a reverse DCF is asking for something plausible: if the price implies a 20% CAGR for a decade, the relevant question is how many companies have ever managed that, and the answer is very few.
A growth rate means different things in different phases
A 30% CAGR is ordinary in hyper growth and remarkable in capital return. Phase Check places any US-listed company on the lifecycle so you know which reading applies before you judge the number.
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Frequently asked questions
Related
- The 5 lifecycle phases, what growth rate to expect at each
- Reverse DCF, the growth rate a price already assumes
- Operating leverage, why profit growth can outrun revenue growth
- Investing glossary, every term used above, defined in plain English