The Countess® II FL Automated Cell Counter is a three-channel (brightfield and two optional fluorescence channels) benchtop assay platform with state-of-the-art optics and image analysis software to automate cell counting. This instrument allows researchers to analyze cells in suspension for a range of characteristics, including cell viability (live, dead, and total cell counts), cell cycle phase, apoptotic stage, and fluorescent protein expression. For a typical cell count, the Countess® II FL Automated Cell Counter takes less than 10 seconds per sample, using autofocusing to enable fast, accurate counts of cells in a population. The cell counting assay is compatible with a wide variety of eukaryotic cells-including clumpy samples -using the standard trypan blue exclusion method to determine cell viability in the brightfield channel.