Choose the hose around airflow, length and the tool. A small hose is light and convenient. A larger hose creates less restriction when the tool needs a lot of air or the run is long.
1/4-inch hose
Light and easy to manage. It is common for trim nailers, staplers and short low-flow work where mobility matters more than maximum airflow.
3/8-inch hose
A good general-purpose step up when you want less restriction for longer runs, impact tools or other higher-air-demand equipment.
Length matters too
Pressure loss increases as air travels through a hose. If you need 50 or 100 feet of reach, hose diameter becomes more important than it is for a 10-foot whip.
Fittings can become the smallest hole in the system
A 3/8-inch hose feeding through tiny restrictive couplers can still choke flow. If you are trying to improve a high-flow setup, look at the complete path from regulator to tool.
For a small pancake compressor
A huge hose will not turn a 2.6-SCFM compressor into a high-volume machine. Choose enough hose to avoid needless restriction, then size the compressor itself to the tool.
Sources used for this answer
Back to class: Air Compressor Class.