As the saying goes, “failing to plan is planning to fail.” Preparation is a key step to any experiment and can help prevent future headaches. To help you plan PEI transfections for AAV packaging, considering using this PEI Calculator. AAV packaging typically requires transfecting three plasmids at specific molar ratios. To get these ratios right, you need to do a few calculations. This calculator can do the math for you and it’s simple to make adjustments for the type of tissue culture dish and number of dishes used. Here’s to making AAV packaging a little easier!