Men's wear in the 1920s is not very different from men's business attire today. A good suit, tie, hat, and shoes were all a man needed to dress in the day. Evening events were much more formal will full tuxedos even for a dinner party with friends.
To dress like a man from the 1920's you will need the following:
Suit – Suit jackets were usually single breasted, with minimal buttons, and had an overall loose appearance. Pants were held high on the waist with pleats at the top and cuffs at the bottom. In cool seasons suits were dark gray, blue or brown wile summer colors were white, ivory, pastels and occasionally pink (Gatsby was a pink suit in novel The Great Gatsby.)
Vest-A daywear vest, if not designed to match the suit, would be a similar shade of color such as tan with an off-white suit, or pastel color with a darker suit.
Shirt- A typical button down dress shirt in white would be most fashionable and comfortable. Collars were "club" style mean they had rounded edges instead of pointed. These can be very difficult to find today.
Tie- Bow ties were more common then neck ties. Bright solid colors or patterns of geometric shapes were the height of fashion. Ties were thinner and a bit longer in the 20's then they are today.
Pocket Square- Also known as a handkerchief, the Pocket Square matched the bow tie in color if not in pattern as well. Pocket Squares were folded in the men's front jacket pocket.
Suspenders- They not only held up men's pants but were a fashion accessory. Belts started to be popular only in the late 1920's.
Hat- Men do not wear hats today as they did in the 1920s. Winter hats included the bowler, flat cap (also known as a cab driver hat), panama (felt), or its cousin the Fedora. Summer hats were made of straw, such as the straw Boater (aka Skimmer) or the Optimo Panama hat. Top hats were still used for formal wear.
Shoes – The final clearance element of a man's dress was his shoes. Two toned spectator dress shoes were the most appropriate. Fringed tongues and wingtips on Oxfords and Brogues were seen repeatedly.