Map tools by question

Each tool answers one question about a place. Every one takes a place in its link, like ?q=Denver, and an account keeps what you make.

How big is it?

Map area calculator (Geo Measure) — outline a field, a roof or a lot and read its area in acres, hectares, square feet or meters, and its perimeter.
Try: Central Park
Acreage calculator — your land, lot or field on a satellite map, in acres with square feet and hectares underneath: for fencing, sod, a listing or a farm field.
Try: farmland near Ames, Iowa
GPS area measure — walk around a field, a farm or a plot with your phone and watch its area grow in acres, hectares and square meters; then straighten the corners on the satellite map.

Radius map — a circle of any distance around an address or a point, with its area and circumference, shared by link.
Try: 5 miles around Austin · 10 km around London
Distance between two places — the straight-line distance between two addresses or cities in km, miles and nautical miles, with bearing, midpoint and height difference.
Try: New York to London · Denver to Pikes Peak
Distance on a map (Geo Measure) — draw a line along a road, a trail or a shoreline and read its length.

Elevation finder — the elevation of any address or point in feet and meters, several points at once.
Try: Denver · Mount Everest
Elevation profile generator (Geo Elevation) — draw a route and get its elevation chart, total climb and descent, highest and lowest points.

3D terrain map — draw a rectangle anywhere and see it in 3D, shaded or with satellite imagery; add a GPX track, download an STL to 3D print it.
Try: Mount Rainier in 3D
Contour map generator — topographic contour lines for any area at the interval you choose; download GeoJSON or KML.
Try: Mount Rainier
Slope map — how steep the ground is, in degrees and percent grade, with avalanche angles (30°–45°).
Flood and sea level map — raise the water level and see which ground lies below it.
Try: Miami · New Orleans
Viewshed: what can I see from here — every place visible from a point at the height you choose, within up to 25 km.

Latitude and longitude finder (Geo Marker) — click any spot for its GPS coordinates in decimal degrees, DMS and DDM.
Try: the Eiffel Tower
Coordinate converter — decimal degrees, DMS, DDM, UTM and MGRS, from a click or a typed value.
Plot points on a map — paste or upload a list of coordinates and see them as markers; export GeoJSON.

GPX viewer — drop a GPX file to see its tracks, routes and waypoints, with elevation, heart rate and speed charts. The file stays in your browser.
GeoJSON editor — draw points, lines and polygons, edit their properties, download or share the GeoJSON.
Map file converter — GPX, KML, KMZ, GeoJSON and CSV to any of the others, with the file shown on a map first.
Common: GPX to KML · KML to GPX · GPX to CSV · CSV to KML · KML to GeoJSON
KML viewer — open a KML or KMZ file from Google Earth or My Maps and see its placemarks, paths and polygons.
GPS tracker (Geo Tracker) — record a GPS track with your phone in the browser, with time, distance, pace and climb, and keep it as GPX.

Five of the tools are also apps for iPhone, iPad and Mac: see the apps. How the site works and who makes it: About.