That all depends on the block size of the host volume. When set at its largest, the largest virtual disk you can present is 2 TB which is the largest volume size that most OSs can address anyway.
This is a good document for VI3.5 http://www.vmware.com/pdf/vi3_35/esx_3/r35u2/vi3_35_25_u2_config_max.pdf
I didnt find a similar document for vSphere. But you dont mention which one you are using. And I dont imagine the maximums have reduced with vSphere, if anything they are higher than with VI3.5