The normal distribution calculator works just like the TI 83/TI 84 calculator normalCDF function. It takes 4 inputs: lower bound, upper bound, mean, and standard deviation. You can use the normal distribution calculator to find area under the normal curve. Then, use that area to answer probability questions. You can also use the normal distribution calculator to find the percentile rank of a number. Do this by finding the area to the left of the number, and multiplying the answer by 100.

The lower bound is the left-most number on the normal curve’s horizontal axis. For negative infinity enter -1E99. The upper bound is the right most number on the normal curve’s horizontal axis.

For positive infinity enter 1E99. Then, enter the mean and standard deviation. If you are using z-scores for the lower and upper bounds, make sure you enter a mean of 0, and a standard deviation of 1.

If you want to learn how to find the area under the normal curve using the z-table, then go and check out How to Use the Z-Table to find Area and Z-Scores.