Depth decides what fits, not width
Most people compare the width of a satchel and ignore the depth. A wide, shallow bag takes a laptop and a notebook and nothing else. Three or four centimetres more depth takes a charger, a lunch and a folded jacket, without looking bigger from the outside.
If you carry a laptop, the models here are specified from 12 to 17 inches. As always, the padded sleeve is the number that matters, not the main compartment.
Leather or canvas
Roughly half this section is leather, the rest canvas or coated. Leather holds its shape and ages into something; canvas is lighter, takes rain better and washes. For a bag that gets set down on train floors and café chairs, canvas is the honest choice and leather the pleasant one.
My take
A satchel is a good bag for a fixed routine and a poor one for an unpredictable day. If you know what you carry and it does not change much, it is the most comfortable format there is on one shoulder. If your load varies, a backpack will treat you better.
Questions we get
What is the difference between a satchel and a messenger bag?
A satchel has a structured flap and usually holds its shape. A messenger bag is softer and built to be swung round to the front while worn.
Can I fit a laptop?
Yes on the models specified for it, from 12 to 17 inches. Check the padded sleeve rather than the outer size.
Does it work with a suit?
Leather with a slim profile does. A wide canvas satchel will read as casual whatever else you are wearing.