Standard Normal Distribution

z-Score Table

Here you can calculate the p-value for a given z-value.

Standard normal distribution table

z-score table

How to read the z-Table

The z-table, or p-value table for z tests, helps you find the cumulative probability associated with a specific z-score. By locating the z-score in the p-value table, you can determine the probability or p-value of observing values up to that point in a standard normal distribution.

Locate the Row for the First Decimal Place of the Z-Score

A z-score typically has two decimal places (e.g. -2.83). The z-table organizes z-scores with one decimal place in the leftmost column, representing the whole number and the first decimal place. For example: If your z-score is -2.83, find the row labeled "-2.8"

Locate the Column for the Second Decimal Place

The top row of the z-table contains the second decimal place of the z-score. For example for a z-score of -2.83, look for the column labeled "0.03" at the top of the table.

Now you just need to locate the cell where your row and column intersect. This cell contains the probability (area under the curve) for the z-score.

How to Use the Z Table for Positive Z-Scores

The z-table only shows negative values, but you can still find the probability for a positive z-score by using the symmetry of the normal distribution. For any positive z-score, the probability is the same as its negative counterpart, since the standard normal distribution is symmetric around zero.

Important: If you want the cumulative probability for a positive z-score starting from the far left, read the table at the corresponding negative z-score and calculate 1 − (table value) to obtain the correct probability for the positive z-score.

Interpret the Value

The value in the cell represents the cumulative probability up to that z-score, or the area under the normal curve from the far left up to that point.

If you're interested, take a look at the t-table, which provides probabilities for given t-values based on degrees of freedom. Alternatively, you can use our statistics calculator to directly calculate p-values for various types of hypothesis tests. tests.