A wet test is a simple at-home method for determining your foot arch type. You wet the bottom of your foot, step onto a flat surface like cardboard or a paper bag, and examine the footprint left behind. The shape of that print, specifically how much of your midfoot makes contact, tells you whether you have a low, neutral, or high arch. Runners and shoe shoppers use it as a quick starting point for understanding their foot structure.
How to Do the Wet Test
You need water, a flat absorbent surface (a piece of cardboard, a brown paper bag, or even a dark-colored piece of construction paper), and a hard floor. Dip the bottom of your bare foot in a shallow pan of water or step onto a wet towel. Then place your foot firmly on the cardboard while standing normally. Don’t press down harder than you would if you were just standing in place. Lift your foot and look at the print.
Do both feet. It’s common for your left and right arches to differ slightly, and knowing that can matter when choosing shoes or insoles.
Reading Your Footprint
Your footprint will fall into one of three general categories based on how much of the midfoot (the area between the ball of your foot and the heel) shows up in the print.
- Flat or low arch: The print shows nearly the entire sole of the foot with little or no curve along the inner edge. The midfoot area is almost as wide as the forefoot. This corresponds to a high “arch index,” a measurement researchers use to describe the ratio of midfoot contact area to total foot contact area. Values above 0.28 indicate a flatter foot.
- Neutral or medium arch: The print shows a distinct curve inward along the midfoot, but you can still see a band of contact connecting the forefoot and heel. The midfoot band is roughly half the width of the forefoot. The average arch index in healthy adults falls around 0.24.
- High arch: The print shows a very thin strip of contact along the outer edge of the midfoot, or the forefoot and heel may appear almost completely disconnected. Arch index values below 0.21 fall into this category.
What Your Arch Type Suggests About Gait
Foot arch type loosely correlates with how your foot rolls when you walk or run. People with low arches tend toward overpronation, meaning the foot rolls inward more than usual after the heel strikes the ground. This extra inward motion can place stress on the ankles, knees, and shins over time. People with high arches tend toward supination (also called underpronation), where the foot doesn’t roll inward enough, leaving the outer edge of the foot absorbing more impact than it should.
Neutral arches generally distribute force more evenly, though plenty of people with neutral arches still develop gait-related problems from other factors like hip weakness or tight calves. Arch shape alone doesn’t determine injury risk.
Where the Wet Test Falls Short
The wet test captures a static snapshot of your foot while you’re standing still. Your arch behaves differently under the stress of walking, running, or jumping. Research comparing static arch measurements to dynamic foot behavior found poor correlation between the two. In one study, the statistical relationship between standing arch shape and arch function during movement was essentially negligible (correlation values of -0.138 and -0.070). The researchers concluded that static and dynamic arch data should be interpreted separately.
This matters because the forces that cause injuries happen during movement, not while standing on cardboard. A person with a seemingly normal static footprint might still overpronate significantly at mile five of a run. Conversely, someone with a flat-looking wet test print might have perfectly functional mechanics when their muscles are engaged during activity.
There are also practical accuracy issues. How much water is on your foot, how hard the cardboard is, how long you stand, and how you distribute your weight all affect the print. Researchers have noted that pressure-sensitive materials (like carbon paper used in clinical settings) record gradations of contact that a simple wet footprint does not. With a wet test, light midfoot contact can look the same as no contact, which tends to skew results toward a higher-looking arch than you actually have.
How Professionals Assess Foot Type
Podiatrists and sports medicine specialists use more reliable tools. The Foot Posture Index (FPI-6) is a six-item clinical scoring system that evaluates foot posture from multiple angles, not just a bottom-up print. It has 100% consensus among podiatry experts as a preferred assessment method. Clinicians also measure resting and neutral heel position, observe how the arch changes between sitting and standing, and in some cases use pressure-sensing platforms that record exactly how force moves through the foot during walking.
These methods capture what the wet test cannot: how your foot actually functions in three dimensions under real loads.
Using Wet Test Results for Shoe Selection
The traditional advice links arch type to shoe category. Low arches are paired with stability or motion-control shoes that limit inward rolling. High arches are matched with neutral, well-cushioned shoes that allow more natural foot motion. Neutral arches get the broadest range of options.
This framework is a reasonable starting point, but it’s an oversimplification. Your wet test result tells you something about your foot’s resting structure, but it doesn’t account for your body weight, running form, weekly mileage, the surfaces you train on, or the dozens of muscles and tendons that influence how your foot actually moves. Many specialty running stores now use treadmill gait analysis or pressure mapping instead of (or alongside) a static footprint to recommend shoes.
If the wet test points you toward a shoe category and those shoes feel comfortable and keep you injury-free, the test served its purpose. If you’re dealing with recurring pain in your feet, shins, knees, or hips, a more thorough assessment will give you better answers than a footprint on cardboard.