Measurement accuracy
98.7% refers to how closely a phone capture reproduces the same foot measured under controlled conditions on average in our data set.
The Fit Process · 30 Seconds · No App · No Shoe Sizes
No shoe sizes.1,500,000+ scans.Just your phone.
Your phone measures your feet more precisely, with 98.7% accuracy. This page is the whole procedure — what we capture, how accurate it is, what happens to the data afterward, and what we do if we get it wrong.
- 30Seconds
- To scan both feet
- 98.7%
- Fit accuracyMeasurement accuracy
- 18
- Feet measurements
- 0
- Scan data kept
in your browser, not an app.
vs 68% buying shoe sizes online.
extracted with every scan.
after processing.
01 — The Science
What Our Scanner is Capturing
You scan both feet with a card from your wallet in the middle of your feet. The camera does not measure anything — our machine learning models do. Our machine learning models use lidar to reconstruct a three-dimensional surface from the frames, then extract the same fixed set of landmarks from that surface every single time.
- Foot length
- Determines the base of the shoe — the only dimension a shoe size describes.
- Forefoot width
- The most common point of contention in footwear sizing.
- Ball girth
- Determines the upper volume. This is what a width letter crudely approximates.
- Instep height
- Decide the height of the foot and the volume needed for the area near your ankle.
- Arch
- Helps us understand how high your feet are and the depth, similar to the in-step height.
- Toe-Joint Length
- Also called heel-to-ball length, measures the distance from the heel to the ball of the foot (the first metatarsophalangeal joint).
- Left and right, separately
- Your two feet are not the same. We measure both independently.
02 — The Process
Five steps. Thirty Seconds Needed.
#1
Open your order
After purchasing, go to Your Orders under the account menu and select the order you just placed.
#2
Start the scan
Press SCAN NOW. The tool opens in your phone browser. Nothing installs and nothing is added to your home screen. Our website app will give you step-by-step instructions.
#3
Scan your feet
Bare feet, hard floor, phone at knee height. Place a card from your wallet in the middle of your feet.
#4
Review and confirm
Your measurements come back on the screen. Read them, then choose the name we etch into the shoe.
#5
We build your pair
Once we confirm the scan, your pair enters the production queue. Track it from the same order page.
03 — Accuracy
98.7% of what, exactly?
A percentage with no denominator is decoration. Here is the denominator.
Fit outcome
The number that matters commercially is different: the share of scanned orders that needed no exchange for fit.
What it does not mean
A precise measurement is not a diagnosis. The scan will not find neuropathy, a stress fracture or a structural deformity. If your feet hurt in ways footwear should not be causing, see a podiatrist.
04 — Your Data
The Scan is Deleted Immediately After Processing.
Photographs of your feet are the most sensitive information we can ask for, so we delete the images immediately after processing your scan. We also encrypt photos during transfer, so your privacy is our top priority.
Your Measurements
The resulting measurements are stored in our database, so you never have to scan again. Order a second pair in two years, and we already know your feet.
What We Never Do
Your measurements are not sold, and are not shared with third parties for advertising. Aggregate, anonymized morphology informs how we design lasts — nothing that identifies you leaves us.
05 — If We Get It Wrong
Thirty Days on Your Feet.Not Thirty Minutes on a Carpet.
A made-to-order pair cannot be tried on in a shop, so the trial happens after delivery instead of before it. Wear them for thirty days. If they are wrong, we will either remake them for free or offer a free return label.
- 30 days
- Free Wear Trial
- Free
- Return Shipping
- 3.85%
- Our Return Rate
30 days to decide if Walking On Air Shoes are right for you.
No restocking fee on a fit-related return.
Against an industry average of 18.5% on footwear bought online.
Find Your Perfect Fit
Pick a pair. Scan from your account. We build to your measurements, not to a size that was invented for a factory.