Wizkids Rules!

You can always pre-measure Range before committing to an Action or Attack of any kind.

However, as far as I can see, there isnt anything to confirm this in the offical FAQ or main rule book.

In the main rule book on page 11 it specifically states you can pre-measure before commiting to a target lock action, however I cannot find anything that confirms this for other card based range Actions.

Yes, you may pre-measure for actions to check if you are within range before using your action, unless a card specifically says you cannot.