torch.Size

Created On: Apr 19, 2024 | Last Updated On: Jun 18, 2025

torch.Size is the result type of a call to torch.Tensor.size(). It describes the size of all dimensions of the original tensor. As a subclass of tuple, it supports common sequence operations like indexing and length.

Example:

    >>> x = torch.ones(10, 20, 30)
    >>> s = x.size()
    >>> s
    torch.Size([10, 20, 30])
    >>> s[1]
    20
    >>> len(s)
    3

class torch.Size(iterable=(), /)

count(value, /)

Return number of occurrences of value.

index(value, start=0, stop=9223372036854775807, /)

Return first index of value.

Raises ValueError if the value is not present.

numel() → int

Returns the number of elements a torch.Tensor with the given size would contain.

More formally, for a tensor x = tensor.ones(10, 10) with size s = torch.Size([10, 10]), x.numel() == x.size().numel() == s.numel() == 100 holds true.

Example:

>>> x=torch.ones(10, 10)
>>> s=x.size()
>>> s
torch.Size([10, 10])
>>> s.numel()
100
>>> x.numel() == s.numel()
True

Warning

This function does not return the number of dimensions described by torch.Size, but instead the number of elements a torch.Tensor with that size would contain.