this link provides different values for std https://github.com/keon/3-min-pytorch/issues/26 in the case of Fashion Mnist, and I think it is because you are computing std per batch. The code that appears on the link is

transforms.ToTensor()
])

dataset = torchvision.datasets.FashionMNIST(root = './.data', train = True,
download = True, transform = transform)

FashionMNIST_mean = dataset.data.numpy().mean(axis = (0, 1, 2))
print(FashionMNIST_mean / 255)
FashionMNIST_std = dataset.data.numpy().std(axis = (0, 1, 2))
print(FashionMNIST_std / 255) ```