JoseFitani
🗂️ Map Generators

Circle Map

Draw circles on a map with any radius. Useful for coverage analysis and planning.

This page explains how the circle map works, the data and formulas behind it, and how to interpret the result. Map tiles come from OpenStreetMap, contributed by volunteers worldwide under the Open Database License. Leaflet is an open-source library for interactive maps that works on desktop and mobile. The tool is one of 329 free, open tools on JoseFitani for maps and geography. It runs in your browser with no sign-up needed. Use the search field or click the map to drop a pin - the tool uses Leaflet-based rendering with OpenStreetMap tiles and returns the result in seconds. Below you'll find a step-by-step guide, real use cases, the methodology, FAQs, and data sources.

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How to use this tool

1
Enter your input

Type your query, paste coordinates, or click on the map. The tool uses Leaflet-based rendering with OpenStreetMap tiles to process your input locally in the browser.

2
View the result

The result appears instantly with the map showing your location. You can adjust by clicking elsewhere or searching a new place.

3
Copy or share

Click Copy to save to clipboard, or Share to send a direct link with the exact inputs.

What people use this tool for

Visualising transmitter coverage zones

Radio amateurs, event crews, and small wireless ISPs can draw circles directly on the map to sketch where a signal should reach. Dragging the circle into place over the actual streets and landmarks makes the coverage plan concrete for the whole team. It is a sketching aid for discussion, not a propagation model.

Example: A community radio station draws a circle over its town to show volunteers the neighbourhoods the new antenna should cover.
Comparing store catchment areas

Retail planners can draw circles around existing and proposed store locations to see where catchments overlap and where gaps remain. Overlapping circles flag cannibalisation risk between two branches, while empty map space highlights underserved areas. The visual comparison beats a spreadsheet of distances.

Example: A coffee chain draws circles around its three downtown shops to decide whether a fourth location would steal customers or serve a new pocket.
Marking safety exclusion perimeters

Construction managers and event safety officers can draw a circle around a hazard — a crane, a fireworks launch site, a fuel store — to mark the keep-out zone on a shared map. Crews see the same boundary on their phones, which beats describing 'about fifty metres from the gate' over the radio. The circle can be resized as the hazard or the regulations change.

Example: A site manager draws a 100-metre circle around a demolition zone so subcontractors know exactly where hard hats and exclusion rules apply.
Sketching search areas for missing persons

Volunteer search teams can draw a circle around the last known position to define the initial search area on a shared map. As clues come in, the circle can be moved or resized and new sectors drawn inside it. Everyone works from the same picture instead of conflicting verbal descriptions.

Example: A mountain rescue team draws a 2 km circle around a hiker's last phone ping to assign search sectors to arriving volunteers.

How it's calculated

A circle on a sphere is drawn as an equidistant polygon from the center point.

The calculation runs in your browser - no data is sent to our servers. Map tiles come from OpenStreetMap (ODbL license), geocoding uses Nominatim (1 request/second limit), and elevation uses the Open-Elevation API backed by SRTM data. All are free, open services.

All calculations use the WGS84 datum (EPSG:4326), the same as GPS. For other datums (NAD27, NAD83, ETRS89), a separate conversion is needed. The difference is typically under 1 metre - negligible for most uses but important for survey-grade work.

The formulas match those in professional GIS software (QGIS, ArcGIS, Global Mapper), just in a browser-friendly form. For sub-metre accuracy, use professional software with ellipsoidal calculations. Results are shown in multiple units: km and miles for distance, km²/m²/hectares/acres for area, metres and feet for elevation. Conversion factors are exact (1 mile = 1.609344 km), so the only error source is input precision.

Related tools and resources

For more tools in this category, explore the related tools listed below. Each tool includes full documentation, examples and FAQs. Explore related tools in our Maps category for complementary functionality. See the Tools index for all 329 tools, or read our blog for in-depth articles on geography and maps.

Frequently asked questions

Can I add multiple circles?

Yes - each click adds a new circle.

What is the difference between Circle Map and Radius Map?

Circle Map is for drawing and positioning circles freely on the map as a visual sketching aid, which suits coverage plans and search areas you adjust by eye. Radius Map centres a circle on a chosen point with a typed numeric radius, which suits zones defined by an exact distance. Choose the one that matches whether you think in pictures or in numbers.

Are the circles true circles on the Earth's surface?

The tool draws geodesic circles, meaning every point on the edge is the same ground distance from the centre. On the flat map display, very large circles can look slightly distorted because of map projection. For the sizes most people use — metres to tens of kilometres — what you see is a faithful circle.

Can I draw several circles on one map?

Yes, you can add multiple circles to compare overlapping zones side by side. This is how planners spot cannibalisation between store catchments or gaps between transmitter sites. Keep the count reasonable so the map stays readable; label each circle if the tool allows.

Does the circle account for terrain blocking a signal?

No, it is a geometric shape that ignores hills, buildings, and other obstacles. A hill between a transmitter and a neighbourhood can block a signal that the circle says should arrive. Treat the circle as a starting sketch and validate real coverage with field measurements or a proper propagation model.

How do I resize a circle after drawing it?

Select the circle and drag its edge handle, or edit its radius value if the tool shows one. The map updates live as you drag, which makes it easy to fit the circle to visible landmarks. Releasing the handle locks the new size in place.

Can I move a circle without changing its size?

Yes, dragging the centre of the circle repositions it while keeping the radius the same. This is handy when a proposed mast location shifts by a street or two. The circle keeps its exact size, so comparisons before and after the move stay valid.

Is this suitable for drawing legal exclusion zones?

It works well for planning and communicating zones, but a drawn circle is not a legal instrument on its own. Regulated exclusion zones need formal documentation, signage, and often survey-grade coordinates. Use this tool to draft the zone, then formalise it through the proper channel.

Does the tool save my circles?

Circles exist in your current browser session and are not stored on a server. Screenshot the map or record each circle's centre and radius to recreate it later. For persistent shared maps, export the data to a proper mapping platform.

Data sources & methodology