GPS Speedometer for Your Car
GPS Speedometer turns your iPhone into an accurate car speedometer: real satellite-measured speed (typically within 1-2%), a big digital display, HUD windshield mode, and automatic speed limit alerts. It works when the dashboard gauge doesn't — broken clusters, classic cars, trailers, rentals. Free on the App Store.
Why Put a GPS Speedometer in Your Car?
The gauge in your dashboard reads what the wheels do. GPS reads what the car actually does. Six features built specifically for driving.
True GPS Speed
Speed measured from satellites, not tire rotations — unaffected by tire wear, wheel swaps, or the factory over-read built into every dash gauge.
Big Digital Display
A dashboard-sized readout you can check at a glance, day or night — in MPH or KPH, digital numbers or a classic dial.
HUD Windshield Mode
Flip the display and reflect it off the windshield for a head-up view — read your speed without looking down.
Automatic Speed Limit Alerts
The app knows the limit of the road you're on and warns you when you cross it — visual, voice, or haptic.
Trip Recording
Distance, max, average, and full route for every drive — exportable as a standard GPX file.
Works Offline
GPS is satellite-based and needs no internet. The speedometer keeps working in dead zones and abroad.
GPS vs Your Dashboard Speedometer
Factory speedometers are deliberately calibrated to over-read — regulations allow up to 10% plus 4 km/h high, and tire wear shifts the error further. GPS measures true ground speed, typically within 1-2%. Read why GPS beats the dash gauge, or check your own car with the speedometer calibration guide.
Your Dash Gauge Over-Reads
By design: regulations forbid a speedometer from ever showing less than true speed, so manufacturers aim 2-10% high. At a true 60 mph, many cars display 62-64.
GPS Reads True Speed
Satellite positioning measures your actual speed over the ground — independent of tires, gearing, and wheel size. Typical accuracy: within 1-2%.
Test It Yourself
Run the app next to your dash on a straight, open road — the gap you see is your speedometer's built-in error. Or try the online speedometer in your browser first.
Built for the Ways Drivers Actually Use It
- Instrument cluster dead or display blank
- Faulty speed sensor or blown fuse
- Accurate speed while you schedule the repair
- Mount the phone in the cluster's sightline
- Vintage gauges drift, bounce, or quit entirely
- No cutting, no rewiring, nothing permanent
- Discreet mount keeps the original interior
- Accurate speed in a 60-year-old car
- Mirrored display reflects off the windshield
- Read your speed without looking down
- Works best at night
- Combines with speed limit alerts
- Towing speed limits are often lower
- Longer braking distances — watch speed closely
- Big display readable across a truck cab
- Average speed for long hauls
- Automatic limit detection on every road
- Visual, voice, and haptic warnings
- Set your own alert tolerance
- Great in rentals and unfamiliar cars
Every Other Car You Drive
- Rentals and borrowed cars
- Motorcycles and scooters too
- One app, any vehicle
- No installation, no hardware
Set Up Your Car Speedometer in Two Minutes
Download the App
Free download from the App Store. Open it and grant location access — that's the only permission GPS speed needs.
Mount Your iPhone
Use a dashboard or windshield mount close to your eye line. Plug into a car charger for longer drives.
Pick Your Display
Big digital numbers or a classic dial, MPH or KPH. Enable HUD mode for night driving.
Drive
Your speed shows in real time. Turn on speed limit alerts and trip recording if you want them.
iPhone GPS vs Dashboard vs Aftermarket Gauge
| Feature | iPhone GPS Speedometer | Dashboard Speedometer | Aftermarket GPS Gauge |
|---|---|---|---|
| Cost | Free | Included with car | $40-300 |
| Accuracy | 1-2% | Over-reads 2-10% | 1-2% |
| Works with a broken cluster | |||
| HUD windshield mode | Rarely | ||
| Speed limit alerts | Some newer cars | ||
| Trip recording & GPX export | Rarely | ||
| Installation | None — mount the phone | — | Wiring or 12V socket |
| Switch MPH / KPH on demand | Fixed dial |
Our Recommendation: In a daily driver with a working gauge, the app adds speed limit alerts, HUD, and trip logs on top. With a broken, missing, or vintage speedometer, it's the fastest accurate replacement — no wiring, no workshop visit.
Car Speedometer FAQ
In practice, yes. Factory speedometers are required to never under-read, so manufacturers calibrate them 2-10% high — and tire wear, pressure, and non-stock wheels shift the error further. GPS measures your true speed over the ground from satellites, typically within 1-2%.
That's by design, not a fault. Regulations (such as UNECE R39 in Europe) forbid a speedometer from showing less than your true speed, and allow it to read up to 10% plus 4 km/h high. Carmakers build in that safety margin, so the dash almost always shows a few mph or km/h more than GPS. Both readings are "working correctly" — GPS is simply closer to your true speed.
No — and we'd rather tell you that straight. GPS measures road speed, not engine revolutions. Reading RPM requires a connection to the engine, e.g. an OBD-II adapter. Note that in many languages "tachometer" simply means speedometer — if that's what you're after, the app fully covers it: it's a complete GPS speedometer for your car.
Practically, yes — mount the phone in your sightline and you have an accurate speed display again within minutes, which is exactly what you need to drive to the workshop and while a repair is scheduled. Legally, most regions still require the car's own speedometer to work for roadworthiness inspections, so treat the app as the bridge, not the permanent fix.
GPS needs a view of the sky, so expect brief dropouts in tunnels and covered garages. The app reacquires the signal within seconds of coming back into the open — on normal roads, coverage is continuous.
Yes. GPS reads true ground speed regardless of load, which is exactly when it matters most: towing changes braking distances, many regions post lower limits for vehicles with trailers, and heavy loads make the factory gauge no more accurate.
Yes — the core GPS speedometer (live speed, max, average, distance) is free. The optional PRO upgrade unlocks speed limit alerts and other advanced features. No account required.
Continuous GPS is battery-intensive — expect several hours on a charge, so plug into a car charger on longer drives. Data usage is minimal: GPS itself needs no internet at all; only the speed limit lookup fetches small amounts of map data.
Keep Reading
Online speedometer
Test GPS speed right now in your browser — nothing to install.
Speedometer calibration
Check how far off your dash gauge really is, step by step.
Broken speedometer replacement
What to do when the cluster dies — causes, costs, and the GPS stopgap.
Classic-car speedometer
Accurate speed in vintage cars without touching the original gauges.
HUD speedometer guide
Project your speed onto the windshield — setup and tips.
Speed limit app
Automatic speed limit detection and alerts on every road.
Free vs PRO
Exactly what's free and what the optional upgrade adds.
Put an Accurate Speedometer in Every Car
Free download with core speed tracking. The optional PRO upgrade unlocks speed limit alerts and advanced features.
Works in any car — broken gauge, classic, rental, or trailer in tow