Runs in your browser — nothing is uploaded
—m
- Lowest
- —
- Highest
- —
- Vertical accuracy
- —
How to use Altimeter
Press Start and allow location. Altitude is shown only when your device’s GPS reports it — the page never estimates or invents a value.
- Press Start outdoors and allow location access.
- Wait for a few fixes; GPS altitude is less precise than horizontal position.
- Switch metres and feet, and watch the range between your lowest and highest points.
Formula & assumptions
- Readings come straight from your device’s sensors and stay on this device. Phone sensors are approximate; use a dedicated instrument where accuracy matters.
Questions
Why does it say altitude is not available?
Many laptops and some browsers report only latitude and longitude. Phones with GPS usually provide altitude once they have a good satellite fix outdoors.
How accurate is GPS altitude?
Typically ±10–20 m, worse than horizontal accuracy. The reported accuracy is shown with every reading.