HowTall: Measure anyone's height in real time with iPhone LiDAR

Hey Product Hunt! I built HowTall because I kept reaching for a measuring tape and not having one. The iPhone Pro already has every sensor you need: ARKit gives 3D body keypoints, the LiDAR scanner gives a real floor plane. Combine them and you can read someone's height in about a second. The trick I'm most proud of: don't trust the skeleton's z depth directly — it drifts with clothing and pose. Instead I cast camera rays through the head and foot pixels and intersect them with the LiDAR scene depth. That keeps the measurement floor-anchored even when the body tracking wobbles. A small temporal smoother on the readout kills jitter without adding noticeable lag. Everything runs on-device. No accounts, no analytics, no servers. Camera + depth frames are processed in memory and discarded. App Privacy is "Data Not Collected" and you can verify in the App Store listing. Free, no IAP. Built solo over the past few months. Requires an iPhone with LiDAR (12 Pro or later, any Pro / Pro Max), iOS 17+. Would love feedback on accuracy edge cases — especially kids (I've only tested adults), sloped floors, and unusual stances. I'll be in the comments all day.