Heat Map
This tool turns a list of coordinates into a density visualization on an interactive map. Paste one latitude,longitude pair per line — or upload a CSV or text file — and click Generate heat map to plot every point.
Each point is drawn as a large, highly translucent red circle, so areas where many points cluster appear progressively darker — the classic heat-map effect, built from overlapping markers rather than a raster heat layer. The tool reports how many points were plotted, how many lines were skipped as invalid, and the bounding box of the data. Everything is computed in your browser; nothing is uploaded.
Dense areas appear darker where the translucent markers overlap. Everything is computed in your browser — no data is uploaded.
How to use this tool
Paste one latitude,longitude pair per line into the text box, or upload a CSV/TXT file with the same format.
Click Generate heat map. Valid points are plotted as translucent circles and the map zooms to fit them.
Check the plotted-point count, the number of skipped invalid lines, and the bounding box of your dataset.
What people use this tool for
Plot delivery addresses as coordinates to see at a glance which neighborhoods generate the most orders.
Plot reported incidents to reveal hotspots that deserve attention, such as potholes or outages by area.
Check whether field observations cover the study area evenly or leave gaps before analysis begins.
How it's calculated
Each input line is matched against a numeric lat,lng pattern (comma, space or semicolon separated); lines that do not match or fall outside valid ranges are counted as skipped and reported honestly. Valid points render as Leaflet circleMarkers with radius 14 px, no stroke, red fill at 0.22 opacity — overlap darkens dense regions. The bounding box is the min/max latitude and longitude of the plotted points. All processing is client-side.
Related tools and resources
Frequently asked questions
How is the 'heat' effect created?
Each point is drawn as a large translucent red circle. Where circles overlap, the color builds up and dense clusters look darker. It is a visual density technique, not a statistical kernel-density computation.
What format do the points need to be in?
One coordinate pair per line: latitude first, then longitude, separated by a comma, space or semicolon — for example 40.7128, -74.0060. Lines that don't match are skipped and counted in the summary.
Is there a limit on the number of points?
There is no hard-coded limit, but thousands of DOM markers can slow older devices. For very large datasets (tens of thousands of points), a desktop GIS tool will perform better.
Is my data uploaded anywhere?
No. Parsing and rendering happen entirely in your browser. Only the OpenStreetMap base tiles are fetched; your coordinate list never leaves your device.
Data sources & methodology
- OpenStreetMap — Base map tiles.
- Leaflet — Interactive map rendering library.