For the Minimalist Comfort-Truss: If you are between sizes, you may want to consider going with the smaller size. When you first receive the Comfort-Truss, it will be a little tight (as it should be). You might have to stretch the waist strap up to 5" to get the velcro fastened. After wearing it for a few days it will start to break in and stretch out a bit. For the Comfort-Truss HD: The HD stretches much less than the Minimalist due to the thickness of the material, so if you are between sizes on the chart, consider going with the next size up.