what is the average gauss of a hard drive magnet?

I just was wondering 'cause I have three#

This table, from the Wikipedia article titled "Rare-earth magnet",
says the remanant field, Br
of a sintered NdFeB magnet is in the range of 1.0 to 1.4 tesla,  or  10 000 to 14 000 gauss.

I am guessing Br is  the field strength inside such a magnet, and the magnitude of B measured at the surface of this magnet would be little smaller, and B at just a few centimeters from the magnet would be even smaller than that.
It will depend on the size of the HDD and how many platters it has. 2.5" drives have much smaller magnets. Some 3.5" only have a single magnet and others have 2. The size of the magnet used may be different from one manufacture to the next. I have several different sized magnets here from various 3.5" drives. Some are larger in surface area then others while some have the same surface dimensions as other but are twice as thick. I've noticed drives with multiple platters have larger magnets then those with a single platter. Of course the larger magnets are stronger then the smaller ones.

The strength of the magnet is dependent on the shape, size and weight of the magnet. The only way to know how strong then are is to use a gauss meter.