The standard definition of equivalent weight is that - it is defined as the mass of an element/compound/ion which combines or displaces 1 part of hydrogen or 8 parts of oxygen by mass. 

It is calculated as -

Eq wt = Mol wt/valency.

For example, consider the equation - 

2H2O + 2e- → H2 + 2OH-

These two wlwctrons are required for the formation of 1 molecule of hydrogen gas. So, we can say, 2 faraday of electricity is needed to produce one mole of hydrogen gas.

Therefore, equivalent mass = Mol mass of hydrogen/2

= 2.016/2

= 1.008 is the equivalent weight of hydrogen in the reaction.