Every garment brand has its own sizing. A medium from Gildan fits differently than a medium from Bella+Canvas, which fits differently than a medium from Next Level. Assuming uniformity across brands is the most common ordering mistake.

The key measurements to request and compare: chest width (measured across the chest, armpit to armpit), body length (shoulder to hem), and sleeve length. These three numbers tell you more than "S/M/L/XL" ever will.

Gildan sizes run large and boxy. Great for budget orders but the cut isn't flattering for everyone. The G500 is a workhorse but reviewers consistently note it runs wide through the chest.

Bella+Canvas sizes run true-to-size with a more contemporary, fitted cut. Their 3001 is a top-tier consumer option. Better for retail-style programs.

Next Level sizes also run slim. Ideal for younger demographics who expect a modern fit.

The safest approach for large orders: request a sample pack of S/M/L/XL in your chosen garment, have a few people try them before you place the full run. A $40 sample investment can prevent a $2,000 return.

For mixed groups where you can't know exact body types (event apparel, community programs), use Gildan: the extra room is more forgiving than too small.