This is where learning to use different knots comes into play. A Windsor knot uses more tie length than a half Windsor. I used to buy all my ties longer as I tied in a Windsor...with a kilt these ties are too long but the excess is easily hidden by tucking into the waistband of the kilt or into the shirt.

As many have already stated, tie should just touch the waistband or top of the belt buckle. A waistcoat is very effective at hiding a 'too short' tie.

Rondo