A high inland plateau
- Input
- Elevação do terreno
- Expected output
- Cerca de 760 m
At that altitude water boils near 97.5 °C instead of 100 °C.
Carregando ferramenta… / Loading tool…
what is my altitude right now
Finding the altitude of the exact spot where you are standing sounds trivial, but it is the measurement GPS does worst. Combining the satellite reading with a digital elevation model solves the problem and also explains why two phones show different numbers.
At that altitude water boils near 97.5 °C instead of 100 °C.
Near sea level, GPS can even return negative values because of the ellipsoidal reference.
Geometry. The receiver computes position from the intersection of spheres centred on the satellites, and every visible satellite sits above the horizon, never below. That makes the vertical component far more sensitive to small timing errors than the horizontal ones. In practice vertical error runs two to three times the horizontal, so a fix with five metres of accuracy on the map can be fifteen metres off in height.
Most likely because it is reporting height above the WGS84 ellipsoid, and along many coastlines the geoid sits twenty or thirty metres below the ellipsoid. The device is not wrong: it is measuring against a mathematical surface that there passes above the real sea. The tool terrain reading corrects for this.
GPS usually fails inside buildings, because the satellite signal is weak and does not pass well through concrete and masonry. Move near a window or step outside. Once a position is obtained, terrain elevation depends only on the coordinate, so it stays correct even if you go back inside.
Tap to turn on GPS. Your location is used only to compute the result on this screen and is never sent to our servers.
These three values are computed from the altitude using the International Standard Atmosphere, not measured. No browser exposes a barometer, so the real pressure right now can differ by tens of hPa as weather fronts pass.
The geolocation specification defines altitude as height above the WGS84 ellipsoid, but operating systems disagree. Android passes through the raw ellipsoidal height, while iOS already converts to height above mean sea level. The difference between the two is the geoid undulation, which across Brazil runs roughly 10 to 30 metres negative. That is why this tool leads with terrain elevation, which is orthometric by definition, rather than the GPS number.
Your position is used only on this screen. Coordinates are rounded before the elevation lookup, and that request goes straight from your browser to the public API without passing through our servers. Nothing is stored.