A tool to quickly calculate probabilities in a normal distribution from a z-score table. You can either use the slider or enter a z-score value in the input field to find, among other things, the percentage of values below or above this value in a standard normal distribution. You can also: - Compute probabilities between two z-scores. - Calculate a z-score by entering a test value, a mean value and a standard deviation. - Read and understand how to use a positive and negative z-table.