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Compound Monthly Growth Rate Calculator

Compound monthly growth rate, the standard measure for early-stage growth. Multiplying a monthly rate by twelve badly understates the annual figure, because monthly compounding is fast.

Also called: monthly growth rate, startup growth calculator.

Compound monthly growth rate
8.99%

8.99% a month, which annualises to 180.95% rather than 107.88%. At this rate the value reaches 331,523.81 in 12 months and doubles every 8.1 months.

Annualised rate
180.95%
Monthly rate times twelve
107.88%
Projected value
331,523.81
Months to double
8.1
Growth multiple
2.81
On sustaining this
A strong growth rate that is demanding but achievable for a period.
How this is calculated

An estimate, not an offer or a guarantee. Projected returns assume the rate you entered holds for the whole term, which no market does.

Method and background

How this is calculated

CMGR is the constant monthly rate that would take the starting value to the ending value. Annualising it means compounding twelve times, not multiplying by twelve: nine percent a month is 181 percent a year, not 108. That gap is why monthly compounding at startup growth rates produces numbers that look implausible and are simply what the arithmetic gives. The doubling period is often the more intuitive statement of the same rate.

the monthly rate that compounds to the observed growth, which annualises by compounding not by multiplying
n
Months

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

growth over a year

Starting value
42,000
Ending value
118,000
Months
12
Project forward
12

Compound monthly growth rate8.99%

(118/42)^(1/12) - 1; note 8.985 x 12 is only 107.8

Open this example

no growth is a zero rate

Starting value
42,000
Ending value
42,000
Months
12
Project forward
12

Compound monthly growth rate0%

boundary

Open this example

Method and limits

What it assumes

  • Constant growth, which no real business sustains for long.

What it deliberately does not model

  • Two points ignore everything in between, including whether growth is accelerating or decaying.
  • High CMGR is almost never sustainable, and projecting it forward far is a modelling error rather than a forecast.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why not multiply the monthly rate by twelve?
Because each month compounds on the last. Nine percent monthly compounds to 181 percent a year, and the multiplication gives 108, which is wrong by a wide margin.