We investigate the variability properties of 84 of the brightest blazars detected by the Fermi LAT using 44 months of Fermi LAT gamma-ray data. We generated light curves with the recently-developed adaptivebinning method (ABM) using constant flux relative uncertainties as well as with fixed binnings. The ABM light curves are free of upper limits and enable more accurate assesments of different parameters, e.g, the duty cycle, the flares’ rise and fall times and the correlation between flux and spectral hardness.