What is the general difference in sea level for high and low tides?

[Oisterman]

I believe there is no "average", as the moon is constantly in different places, so each day it is different.

I suppose if you wanted an average over an amount of months or years, you could...but not an average of over one month. That information wouldn't be very accurate comparing month to month.

[Ronin]

http://en.wikipedia.org/wiki/Tide_table

[lhsmith]

I checked wiki and this what i get

"Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth."

[V-Opolis]

from my expereince not sure if its valid or not it can be several feet to several tens of feet.