Here, you calculate the doubling time of your cells online. It's helpful to manage cell culture.
Two Time Points 
Several Time Points

Do you like this tool?
Does it help you? 


Would you recommend this tool ? 

EXAMPLE: Doubling Time = 21.86=ln(2)/0.0317 Growth Rate = 0.0317 Growth Rate = number of doublings that occur per unit of time Equation : amount=0.5288*e^{0.0317*time} At t=0, calculated cell concentration = 0.5288


How to cite Doubling Time ?
Cite this website as following:
Roth V. 2006 <http://www.doublingtime.com/compute.php>
Reference for exponential regression
Weisstein, Eric W. "Least Squares FittingExponential."
From MathWorldA Wolfram Web Resource. http://mathworld.wolfram.com/LeastSquaresFittingExponential.html
Tips
The doubling time equation works for any kind of exponentially growing object.
I didn't mention any unit for time and concentrations. It's not necessary.
Keep in mind that the doubling time unit is the same than the one you used for the duration.
Instead of using concentration of cells, you can use the number of cells.