You are behind the wheel of an imported Skyline, and the cluster only shows kilometers per hour. Traffic is moving, and your attention belongs on the road, not on mental math.

That is exactly why I built eyeSpeed’s unit switching. Whether you drive a JDM import, verify an older speedometer, or just prefer one unit over another, switching between MPH and KPH is immediate.

How Unit Switching Works

eyeSpeed displays speed in either MPH or KPH, and you can switch with a single tap on the unit label. No menus. No digging through settings.

On first launch, eyeSpeed checks your device’s regional settings and chooses the default unit accordingly. Metric regions see KPH. Regions that use miles see MPH.

This happens entirely on-device using your locale settings. No server calls, no data collection.

The Unit Lock Feature

I learned quickly that accidental unit changes while driving are annoying and unnecessary.

That is why eyeSpeed includes unit lock. When it is enabled, tapping the unit label does nothing until you unlock it in Settings.

You can toggle it in Settings or via Siri and iOS Shortcuts.

KPH vs km/h: Choose Your Label

Different regions display kilometers per hour differently. Some prefer “KPH” while others expect “km/h.”

eyeSpeed lets you choose either label. Same measurement, different convention.

Privacy-First Unit Switching

Every conversion happens on your device. Your speed is calculated from GPS data, converted locally, and displayed instantly. No server knows which unit you prefer.

That is part of the larger eyeSpeed architecture: local processing, local preferences, and no cloud sync for something this simple.

Shortcuts and Siri Integration

eyeSpeed’s unit switching works with iOS Shortcuts and Siri, so you can control it hands-free:

“Hey Siri, set unit in eyeSpeed to MPH” - Switch to miles per hour without touching your phone
“Hey Siri, set unit in eyeSpeed to KPH” - Switch to kilometers per hour
Create automation shortcuts - Switch units when you connect to CarPlay, change Focus modes, or enter a different region

That makes eyeSpeed easier to use when unit switching actually matters.

Technical Details for the Curious

Under the hood, eyeSpeed uses iOS’s Locale system and Locale.current.prefersMetricSpeed to choose a sensible default.

The conversion itself is straightforward: MPH to KPH multiplies by 1.60934, and KPH to MPH divides by the same value.

Your unit preference and lock state persist between launches without any network sync.

Driving It Home

Unit switching sounds simple until you actually need it. For import owners, international drivers, and anyone verifying an older cluster, getting it right matters. eyeSpeed keeps it fast: tap to switch, automatic defaults, optional unit lock, and your choice of metric label.

And like everything in eyeSpeed, it happens locally on your device. No tracking, no extra complexity.