Architects and designers
A 3D site base for massing studies and early design in SketchUp, Revit or Rhino before a survey is ordered.
Contour map DXF examples
Plots of the contours behind each DXF, rendered by the tool's own code in the coordinate system named on the sheet. Open one to load the area; the layer preview under DXF for CAD shows what the file will contain.
How to get contour lines into CAD
- Choose the site. Search the address, draw a rectangle or polygon, or import the property boundary as a KML or GeoJSON polygon. For a single lot, keep the area small so a 1 or 2 m interval stays readable.
- Pick the data and interval. Free Terrain Tiles cover the world. For a US site, choose USGS 3DEP 1 m lidar (Pro) and a 1 ft to 1 m interval. Units can be meters or feet.
- Set coordinates and drawing units. Under DXF for CAD, choose the UTM zone or the State Plane zone your project uses, and meters, feet or US survey feet. The preview lists the layers and the coordinate system.
- Download the DXF. Pro builds the file on our server in memory from the contours on your map and sends it straight back. Nothing is stored.
- Open it in your CAD program. Open or insert it in AutoCAD, Civil 3D, BricsCAD or SketchUp Pro. Layers come in as CONTOUR_ plus the elevation, index layers in orange and the rest in light brown.
What is inside the DXF
The file is DXF release 12 (AC1009), the version every CAD reader opens, from current AutoCAD and Civil 3D to LibreCAD, QGIS and GDAL. Each contour line is one POLYLINE entity with its elevation as the Z value, so the drawing is 3D from the start. Closed rings such as hilltops come in as closed polylines; lines that cross the edge of your area stay open.
| Part | What you get |
|---|---|
| Layers | One per elevation: CONTOUR_1600, CONTOUR_1602_5, CONTOUR_-20 for sea-floor lines |
| Colors | Index layers in AutoCAD color 30 (orange), others in 33 (light brown) |
| Elevation | Polyline elevation and the Z of every vertex, in your drawing units |
| Coordinates | WGS84 longitude/latitude, the UTM zone of the area, or a NAD83 State Plane zone |
| Units | Meters, international feet or US survey feet, set in $INSUNITS so CAD scales on insert |
| Notes | Coordinate system, units, interval and data credit as comments at the top of the file |
AutoCAD and Civil 3D
In AutoCAD, open the DXF on its own or insert it into your project drawing. Because the units are set in the file, AutoCAD scales it on insert. In Civil 3D, use the polylines as surface data: create a TIN surface, open its definition in Prospector, right-click Contours, choose Add and select the lines. The surface picks up the elevations directly. Index layers make it easy to freeze the intermediate lines on a plotted sheet.
SketchUp
SketchUp Pro imports DXF under File, Import, AutoCAD Files. Set the import units to match the drawing units you chose, import, then select the contours and run Sandbox, From Contours to build a terrain mesh you can place a model on. A small area with a 1 or 2 m interval keeps the mesh light. SketchUp Free cannot import DXF.
QGIS and other GIS
QGIS opens the DXF as a vector layer, but GIS users are usually better served by the GeoJSON (free) or the zipped Shapefile (Pro), which carry the elevation as an ELEV attribute and, for the Shapefile, a .prj file with the coordinate system.
Lidar contour map for US sites
Free contours come from Terrain Tiles: about 10 m data in the US and about 30 m elsewhere, resampled to about 15 m for small areas. That is enough for the shape of a hill but not for a lot line, a driveway or a drainage swale. With Pro, choose USGS 3DEP 1 m lidar as the data source and the browser downloads the bare-earth model straight from the USGS National Map service. The comparison above shows the difference on Queen Anne Hill in Seattle: 260 lines against 83 over the same square kilometer.
- Coverage: the United States, where 3DEP has flown 1 m lidar. Where it has not, USGS fills the gap with its 1/3 arc-second (about 10 m) data.
- Resolution: 1 m for areas up to 10 km²; larger areas, up to 2,000 km², are sampled coarser so the browser can hold the grid, and the label says so.
- Accuracy: quality level 2 lidar is specified at 10 cm RMSEz, enough for contours of about 1.1 ft by the 1947 accuracy standard. The free 10 m data supports about 5 m. The elevation contour map guide shows the full table and sources.
Who downloads contour DXF files
Civil engineers
Feasibility surfaces in Civil 3D for road alignments, pads and earthwork estimates, replaced later by survey data.
Landscape architects
Contours on the right layers for grading concepts, planting on slopes and drainage sketches. The land contour map guide covers reading drainage.
Model makers and students
Contours with real heights for site models, studio projects and laser-cut terrain.
How to choose a contour interval
For CAD, the interval should match what the data supports: 1 to 2 ft or 0.5 m with US lidar, and 5 m or more with the free data. Find your area and relief below, and check the data column.
| Area you select | Terrain | Relief | Interval, m | Interval, ft | Data that supports it |
|---|---|---|---|---|---|
| House lot or building site, under 0.1 km² (25 acres) | Gentle to hillside | 5–25 m | 0.5 | 1–2 | 3DEP 1 m lidar (Pro, US) for survey-grade lines; free data shows the shape |
| Small farm or acreage, 0.1–2 km² | Rolling | 20–100 m | 0.5–2 | 2–10 | 3DEP 1 m lidar (Pro, US) for survey-grade lines; free data shows the shape |
| Farm, ranch or park, 2–10 km² | Hilly | 100–300 m | 2–10 | 10–20 | 3DEP 1 m lidar (Pro, US) for survey-grade lines; free data shows the shape |
| Town or valley, 10–50 km² | Hills to foothills | 300–800 m | 10–20 | 20–80 | Free data in the US; elsewhere use 20 m or more |
| Mountain area, 50–100 km² (free limit) | Mountains | 800–2,000 m | 20–50 | 80–200 | Free data, worldwide |
| Range or region, 100–2,000 km² (Pro) | High mountains | 1,500–4,000 m | 50–100 | 100–500 | Free data, worldwide |
Relief is the highest minus the lowest elevation in your selection (the tool shows both under Map data). Interval = relief ÷ 50, rounded up to 0.5, 1, 2, 5, 10, 20, 25, 50, 100 or 200 m (1, 2, 5, 10, 20, 40, 50, 80, 100, 200, 250 or 500 ft). The last column applies the 1947 National Map Accuracy Standard, interval ≥ 3.29 × the data's vertical RMSE: about 0.3 m for lidar, 5.1 m for the US 10 m data and 18 m for SRTM.
Frequently asked questions
Do the contours in the DXF have elevations?
Yes. Every contour is a 3D polyline whose elevation is its height, repeated as the Z value of each vertex, so AutoCAD, Civil 3D and SketchUp place the lines at their real heights. Each elevation is also on its own layer named CONTOUR_ followed by the height, for example CONTOUR_1600.
Which coordinate system is the DXF in?
You choose: WGS84 longitude and latitude, the UTM zone of your area in meters, or a NAD83 State Plane zone in the US. Drawing units can be meters, international feet or US survey feet. The choice, the units and the interval are written as comments at the top of the file.
Can I get a DWG file?
The tool writes DXF, which AutoCAD, Civil 3D, BricsCAD and SketchUp Pro open directly. To get a DWG, open the DXF in AutoCAD or BricsCAD and save it as DWG, or convert it with the free ODA File Converter.
How do I make a Civil 3D surface from the DXF contours?
Open or insert the DXF, create a TIN surface, then in Prospector expand the surface definition, right-click Contours and choose Add. Select the contour polylines and keep weeding and supplementing at their defaults. The polylines already carry their elevations, so the surface builds without editing.
Does the DXF work in SketchUp?
SketchUp Pro imports DXF through File, Import with the AutoCAD Files type. Choose the matching units in the import options, then use the Sandbox tool From Contours on the imported lines to build a terrain mesh. SketchUp Free on the web does not import DXF; export the SVG instead for a flat plan.
What is a lidar contour map and where is it available?
A lidar contour map is drawn from a laser-scanned ground model rather than a satellite one. With Pro, choose USGS 3DEP 1 m lidar as the data source for an area in the United States. Areas up to 10 km² are sampled at 1 m; larger areas are sampled coarser and say so. Outside the US, use the worldwide Terrain Tiles data.
Is a DXF from this tool good enough for a site plan?
It is a good base for planning, feasibility and design concepts. It is not a survey: the contours come from public elevation data with the accuracy listed on this page, and permit drawings, grading plans and boundary work need a licensed surveyor.
More contour tools and guides
Contour map generatorAny area and interval, with free PNG, GeoJSON, SVG and KML downloads.Topographic map generatorElevation tints, labeled index lines and print sheets with a scale bar.Contour map SVGVector contours for posters, laser cutting, Figma and Illustrator.Google Earth contour linesKML and KMZ contour overlays that sit on Google Earth terrain.Elevation contour map guideWhere the elevation data comes from, its accuracy and how to pick an interval.Land contour map guideRead slope, ridges, valleys and drainage on a property or farm.