While there are barbells which are built to a certain specification, majority of the barbells available on the market feature different grip diameter. Most common barbell diameters are: 1. Powerlifting – 29 mm grip diameter. 2. Olympic Weightlifting – 28 mm grip diameter. 3. Hybrid barbells – 28.5 mm grip diameter. 4. General Strength Training barbells – 30-32mm grip diameter. 5. Women’s Bars – 25 mm grip diameter. 6. Strongman/Fat Grip Barbells – 50 mm grip diameter. 7. Specialty Deadlift Barbells – 27 mm grip diameter. 8. Specialty Squat Barbells – 32 mm grip diameter Specialty Barbell Grip Diameter (EZ Curl, Super Curl, Triceps Bar, Multi-Grip Bar) – grip diameter can range from 25 mm all the way up to 32 mm. For powerlifting, bodybuilding, and general strength training, I would recommend choosing a barbell which has a diameter of 29-30 mm. Barbells with thinner grips will be whippier (has more flex). While barbells with THICKER SHAFTS can be more difficult to hold on to.