How do I calculate buffer capacity?

There are several steps to follow to calculate buffer capacity. 

1. Find the initial pH and final pH using the Henderson-Hasselbalch equation
2. Subtract the final pH from the initial pH
3. Divide the number of moles of a base or acid added to the buffer solution by the change in pH. This step results in the buffer capacity 

In equation terms, it looks like the following: 

Buffer capacity = # mol/L (of an acid/base)  / final pH - initial pH