The size of branches that a wood chipper/shredder can handle will vary depending on the model and brand. Electric chippers generally have a smaller chipping capacity, typically up to 1-1/2 inches in diameter, while gas-powered chippers typically have a larger chipping capacity, up to 3 inches in diameter or more. However, some models can handle up to 4 or even 6 inches in diameter. It's important to check the manufacturer's specifications to determine the maximum branch diameter the machine can handle. It's important to note that feeding branches that are too large for the machine can cause damage to the blades, or even clog the machine, so it's always a good idea to stick to the recommended size range. Additionally, always check the manual or the specifications of the machine, as some models may have different chipping capacity depending on the type of wood or other materials you are using.