Recess Sizes:- The tight size from side to side and top to bottom. If recess sizes are quoted we take the appropriate allowance off the blind before manufacture.

Blind/Exact Size :- The exact size which you require the blind to be manufactured.

Fabric/Material size:- Usually used for roller blinds for doors e.g. if your glass size is 27 inches wide you would require the material to cover at least 1/2 inch each side therefore your fabric size would be 28 inches by the drop. 

Always quote the width by the drop.

When measuring your blinds always allow for the fitting point, so the blinds don't hit handles or other objects.