Figuring Out Your Nike Size Without Guessing
Nike N Lock is their foot scanning system built into the Nike app. You hold your phone over each foot, it takes a few photos, and then it gives you a recommended Nike size along with 22 measurements of your foot. It exists because people were buying the wrong size online and returning shoes at an alarming rate. I set this up on my phone about two years ago when I started buying running shoes exclusively online. The whole scan takes maybe 30 seconds per foot if you're doing it right. You put your phone flat on the ground, slide each foot into the frame, and follow the prompts. After that you get a size recommendation and a breakdown of whether the shoe runs true to size, large, or small.
Unlock Your Potential The Ultimate Guide To Nike N Lock For Performance Fit
Here is how you actually get it working. Open the Nike app, go to the search bar, and type "N Lock" or "Nike Fit." Tap the result and you'll see the scanner interface. Stand on a flat hard surface with good lighting. Natural light works best. The scanner needs to clearly see the outline of your foot from above and the side. Carpet textures confuse it sometimes, so tile or hardwood is better. Place your phone screen down on the ground. Put one foot into the guide on your screen, keeping your weight evenly distributed. Hold still for three seconds while it captures the top view. Then angle the phone to capture the side profile. Repeat for the other foot. The app compiles both and gives you a Nike size with a confidence percentage. The measurements it provides include length, width, instep height, and arch type. Those last two matter more than people realize. I wore a size 10 in Nike trainers for years without checking. N Lock told me my right foot was 27.4 centimeters and my left was 27.2. It recommended a 10.5 for both with an 87 percent confidence score. I ordered the 10.5s. They fit correctly. My old approach had me dealing with a tight left foot and a sloppy right foot every single time.
There are some edge cases the app does not handle well. If you have a very high arch or a wide forefoot, the scan sometimes underestimates your width. I ran into this with my second pair of Pegasus. The scanner gave me a 10.5, but the toe box felt pinched. I measured my foot manually with a ruler and found my actual length was closer to 28 centimeters. I went up half a size and that fixed it. For people with unusually wide or narrow feet, the N Lock recommendation should be treated as a starting point, not gospel. Another thing nobody mentions is that the technology works differently depending on your phone. iPhones with LiDAR scanners, like the iPhone 12 Pro and newer, produce noticeably more accurate results than older cameras or Android devices without depth sensors. I tried it on my partner's older Samsung and the width measurements were off by nearly a half size compared to the same scan on my iPhone. If your phone is more than three or four years old, expect less reliable data. The biggest limitation is that N Lock only works within the Nike ecosystem. It will not tell you your Adidas or New Balance size. It also does not account for the specific shoe model you are buying. The recommendation is based on Nike's general last, which means you might still need to adjust if you know a particular model runs narrow like the Vaporfly or roomy like some of the older Air Max designs.
Get the Full Details
For performance use, I recommend pairing the N Lock output with a manual measurement. Grab a piece of paper, trace your foot, measure the longest toe to the heel, and compare it to Nike's size chart. If the N Lock recommendation matches your manual measurement within half a size, trust the scan. If they diverge, go with the larger size. A shoe that is slightly too big is easier to live with than one that is too tight, especially for running where your feet swell during activity. Use it. Save the results in the app. Next time you order, check whether your foot measurements have changed. They do, slowly, especially if you gain or lose weight. I checked mine again after a six month training block and my size recommendation shifted from 10.5 to 11 based on the swelling from increased mileage. That was useful information I would have missed otherwise.
Common Mistakes That Ruin Your Scan
Wearing thick socks during the scan throws off the measurements. Do it barefoot. Standing on a rug creates shadows that the camera interprets as part of your foot outline. Use a hard flat floor. Having someone else hold the phone instead of placing it on the ground themselves leads to angle errors. The app expects a specific overhead and side angle. Stick to that. Also do not use this immediately after a long run when your feet are maximally swollen. You will get a larger reading than you normally need, and then your daily shoes will feel loose. Scan in the morning when your feet are at their standard size, or late afternoon for a middle ground. The Nike Fit feature is free to use with no download required beyond the standard Nike app. It is available in most markets where Nike sells shoes directly. Check your app version first. Older versions of the Nike app did not include the N Lock scanner, and if you have not updated in a while, that could be why you cannot find it. Go to your app store and make sure you are running the latest version.
I have used this for running shoes, basketball shoes, and casual sneakers. It works across all of them, though the confidence score tends to be higher for running and training shoes since Nike has more data on those lasts. For specialized footwear like climbing shoes or racing flats, the scan is less reliable because those categories have smaller sample sizes in Nike's database. If you are buying Nike products regularly, this is worth five minutes of your time. If you buy once a year, probably not worth the effort to set up. The accuracy gain diminishes if you are only making one purchase a year because you will forget the results anyway and end up guessing again.
