I've been asked many times, how to calculate percentage change. So here is a handy calculator for your convenience, and a permalink to any changes you make below.

VariableDefinitionValue
Value 1 
Value 2 
% change, 1 → 2 (V2 - V1) / |V1|
% change, 2 → 1 (V1 - V2) / |V2|
% ratio, 1 : 2 V1 / V2
% ratio, 2 : 1 V2 / V1
% difference|V1 - V2| / ((|V1| + |V2|)/2)

One needs to be careful when interpreting or phrasing the above results.
For example, if v1 and v2 are benchmark times, one can either say that:

The percentage difference value can be used where there is no directionality implied, and one just wants the relative difference between two values.

© Apr 9 2011