PyTorch Guides

In-depth tutorials for fixing common PyTorch errors and understanding tensor shapes. Each guide includes code examples, debugging steps, and interactive tools.

Fix "mat1 and mat2 shapes cannot be multiplied"

Complete guide to fixing PyTorch RuntimeError: mat1 and mat2 shapes cannot be multiplied. 7 real-world causes with code fixes, interactive shape checker, and prevention tips.

About These Guides

Each guide covers a specific PyTorch error or concept in depth, with real-world code examples, step-by-step debugging processes, and links to the relevant HeyTensor tools. Use the Tensor Shape Calculator to verify shapes interactively as you follow along, or try the mat1/mat2 error debugger to paste your error message and get an instant fix.

Built by Michael Lip. All guides are free and open source.