What size pancake compressor do I need for a brad or finish nailer?

A standard 6-gallon, 150-PSI pancake with around 2.6 CFM at 90 PSI is sufficient for 18-gauge brad nailers, 16-gauge finish nailers, and most trim work. Across the reviewers we read, this is the dominant use case these compressors are designed for. For framing or roofing nailers run continuously, look for higher CFM (around 4 CFM at 90 PSI) and 200 PSI tanks like Metabo HPT's 'The Tank.'