How we measure hats
Every hat gets the same protocol: up to ten measurements in millimeters and grams, seven photos, the fit on a measured head and a dated log of every session it was worn for. Every spec table on the site links here.
By Fitness Hats Editorial Team, published October 21, 2026
Equipment
- Digital kitchen scale with 0.1 g resolution
- Flexible tailor’s tape in millimeters
- 30 cm steel ruler
- Phone on a tripod at a fixed distance, with a plain gray or white backdrop
- A 10 cm scale bar in every profile photo
Two readings, every time
We take every measurement twice. If the two readings differ by 2 mm or more, we take a third and record the median. Weight is the average of two readings, dry, with tags removed.
The measurements
Visors skip the crown measurements; bucket hats skip brim width and curve.
| Measurement | Unit | How |
|---|---|---|
| Weight | g | Dry, tags removed, on a 0.1 g kitchen scale. Average of two readings. |
| Inside circumference, smallest | mm | Tape inside the hat along the lower edge of the sweatband, closure fully tight. Fitted hats: the one value. Stretch-fit: relaxed. |
| Inside circumference, largest | mm | Same line, closure fully open. Fitted hats: same as smallest. Stretch-fit: gently stretched. |
| Crown height (front seam) | mm | Front center seam, outside, from the lower edge of the sweatband to the base of the button, tape following the curve. |
| Back seam | mm | Back center, from the top of the closure (or the sweatband on a closed back) to the button. |
| Side arc | mm | Inside, from the sweatband edge above one ear, over the button, to the same point on the other side. |
| Brim length | mm | Center front, from the crown seam straight out to the brim edge. |
| Brim width | mm | Tip to tip in a straight line. |
| Brim curve | mm | Ruler across both brim tips; the largest gap at center between ruler and the underside. Flat is 0. |
| Sweatband width | mm | Height of the sweatband at center front, inside. |
Low, mid and high crowns
Brands call a crown low, mid or high without saying what that means. We do not pick the cut points in advance: once we have measured 30 caps, the lowest third of front seam heights is low, the highest third is high, and the numbers are published here. Until then, profiles show the front seam in millimeters and no label.
Photos
Seven per hat, same tripod distance and light, cropped 4:5, at least 1200 px on the long edge. Our own photos only, never a brand's product shots.
- Front. Camera at crown-center height.
- Left profile. At 90 degrees, with the 10 cm scale bar in frame (shows crown height and brim length).
- Back. Shows the closure.
- Top down. Shows the brim shape.
- Inside. Underside with the sweatband and the size label legible.
- Detail. Close-up of vents, reflective trim or fabric.
- On head. On the tester, front or profile. The caption gives the tester head circumference.
Fit
Fit is recorded on a measured head: the tester's head circumference, taken with the same tape, sits next to every fit note, so you can compare it with yours. We record whether the hat felt snug, good, loose or did not fit, whether it sat low, normal or high, and whether an adjustable back left a gap. We never say a hat fits a head size nobody tried. For other heads we give the measured inside range instead.
Wear log
Every session a hat is worn for gets a dated entry: the activity (run, lift, hiit, walk, other), minutes, temperature, whether sweat reached the eyes, and notes. A hat needs at least 3 logged sessions before its profile carries a verdict, and before it can appear in any best-of list.
Manufacturer claims, prices and size charts
Fabric, UPF and sweatband materials are the brand's claims, not our findings. We quote them with a link to the page they came from and the date we read it. Prices come from the brand's own site with the date checked, and disappear after 60 days. Size charts are copied exactly from each brand's own site, dated, and re-checked at least every 180 days (see the hat size chart and its calculator).
What we never do
- Give scores, stars or rankings that a measurement does not support.
- Say a hat was tested, worn or washed unless the log shows it.
- Estimate a number we did not measure, or round a brand's chart.
- Accept payment for a placement. If a brand sends a hat for free, its profile says so.
The first hats measured with this protocol will publish as profiles, each linking back here.