Finding the elevation of an address
Type the address into the search box and press Look up. The page finds the address on OpenStreetMap, reads the ground height at that point from the elevation model, and shows it on the brown sign with the city, county and ZIP code. You do not need to share your own location to use it.
After a lookup, tap anywhere on the map to read the elevation of a different spot, such as the back of a lot, the bottom of a driveway or a nearby hilltop. Each tap is a new lookup, so you can walk across a property point by point.
Coordinates work too. Paste a latitude and longitude, for example 39.7392, -104.9903, and the page reads the elevation at that exact point.
Why people look up the elevation of a property
- Buying a home: a lot that sits a few feet above its neighbours drains better and floods less. Comparing points around a property shows which way the ground falls.
- Flood insurance: in a FEMA flood zone, the premium depends on the height of your lowest floor compared with the base flood elevation. Only a licensed surveyor's Elevation Certificate counts for insurance, but a quick check tells you whether it is worth ordering one.
- Gardening and landscaping: the lowest part of a yard is where water collects and frost settles.
- Canning and baking: recipes and processing times depend on the elevation of your kitchen.
- Radio and antennas: height above the surrounding terrain decides line of sight.
- Planning a route: comparing the start and end of a hike or bike ride shows the total climb.
Where the elevation data comes from
The heights come from an open elevation dataset, AWS Terrain Tiles, which combines the best public sources for each area. In the United States that is mainly the USGS 3D Elevation Program, a bare-earth model that in many areas is built from airborne lidar, the laser scanning that maps the ground under trees and buildings. Elsewhere it uses global datasets such as the Shuttle Radar Topography Mission.
The page reads the value at zoom level 15, where each cell is about 5 metres across at the equator and smaller at US latitudes. That is fine enough to tell the top of a levee from the field beside it, but not the step up to a front porch.
The number is the height of the ground, not the top of a building. For the height of your floor, add the height of the foundation and any floors below.
Comparing points and working out slope
To estimate the slope between two points, look up both, subtract the lower elevation from the higher, and divide by the horizontal distance between them. A rise of 1 metre over 20 metres is a 5 percent grade. For accessibility ramps in the US, the ADA limit is 1 in 12, about 8.3 percent.
Keep in mind that each reading can be off by a metre or so, so slope estimates over very short distances are rough. Over longer distances, such as the length of a street or a trail, the errors matter much less.