In this table, the size label used on the ExplorerHats.com website listed in the top row. Corresponding measurements for these sizes are listed underneath each label.
| Label | S | M | L | XL | 2XL | 3XL |
| Size | 6 3/4 to 6 7/8 | 7 to 7 1/8 | 7 1/4 to 7 3/8 | 7 1/2 to 7 5/8 | 7 3/4 to 7 7/8 | 8 |
| inches | 21 1/4 to 21 5/8 | 22 to 22 3/8 | 22 3/4 to 23 1/8 | 23 1/2 to 24 | 24 3/8 to 24 3/4 | 25 1/8 |
| cm | 54 to 55 | 56 to 57 | 58 to 59 | 60 to 61 | 62 to 63 | 64 |
Head Measurements: Use a tape measure or a non-stretch piece of string to measure the circumference of your head in inches or centimeters. This measurement should be made where the hat will sit on your head – typically just above the ears. Once you have the measurement, find the measurement on the chart above and note the size label it is listed under and this will match the sizes listed with each product.
If your measurement is in the middle of two sizes, it is recommended to chose the larger size. In most cases where a hat is just slightly too large, a reducing tape may be used to make it more snug. This tape is placed behind the sweatband and is essentially just an adhesive backed foam. This can also be found in hardware stores sold as door and window seal. Since the smallest size for many hats is Medium, those with a size small head can consider a much larger selection if using a size-reducing tape. Please feel free to ask advice on this option for any particular hat. Those with large heads in the 2x and 3x size may be able to use a hat-stretcher on some hats – although once you stretch a hat, keep in mind, it cannot be returned if it still doesn’t fit.
Other Types of Sizing: Some hats are “one size” or “adjustable” – the “one size” hats feature an elastic band and typically fit S-L heads. The “adjustable” hats often fit S-2XL. Occasionally hats have a S/M and L/XL designation. These have some elastic stretch, but not as much stretch as a “one size” hat.