Is there a rule of thumb?

[Dick Sylvan]

For the proper placement of two hinges on a door?

[Lee Schierer]

I usually go for what looks good. I don't believe there are any hard and fast rules. Generally I put them 1/4 the distance of the overall length of the door in from each end of the door.

[Tom Veatch]

Like Lee said, what looks good. If there's no other considerations such as extreme weight or size of the door, spacing from the top and bottom somewhere around 25% to 30% of the overall length should give the best appearance. 27.6% would give you the "Golden Ratio" of the shorter end spaces to the longer central space.

[Mark Singer]

If you use 2 hinges they act as the resisting couple to the torsion generated by the door and the moment forces. It is good to have the hinges separated .