Hi @Naif40, as explained by @ptrblck, you could use torchsummary for example, which will give you some estimate of gpu usage in MB.
Hence, you could multiply from your current image size (CMIIW, maybe what you mean is 64x64 or 3x64x64 with format Channel x Height x Width):

i.e. 3x 64 x 64, let’s say the output of torchsummary is 1000mb
to know your limit is: 8000 / 1000 =  8. It could be used to increase your image size into: 3x181x181 (sqrt of 8 is ~2.82).

But again, this is an estimation, and Pytorch should prevent you to use 100% of your gpu resources due to GUI utilization or other processes etc.
So, use it with keeping those things in mind. Hope it helps, cheers~