Enter the length of the query sequence, the total number of lengths of all template sequences, and the bit score into the calculator to determine the E Value.

## E value Formula

The following formula is used to calculate an E-value in BLAST.

E = m*n*2^-S

- Where E is the e-value
- m is the length of the query sequence
- n is the total number of lengths of all template sequences in file
- S is the bit score

## Example Problem

**How to calculate E-Value? **

First, determine the length of the query sequence. For this example, the sequence length is found to be 10.

Next, determine the total number of lengths in all of the template sequences in the file. For this problem, this value is 50.

Next, determine the bit score. We will use 3.

Finally, calculate the e-value using the formula:

E=m*n*2^-S

= 10 *50*2^-3

= 62.5.