title: Displaying Radius in Meters with Folium
body: <p>I am having trouble understanding how the radius option works with Folium.  </p>
  
  <p>I have the following code:</p>
  
  <pre><code>import folium
  
  lat = 40.7787006
  lon = -73.9654842
  
  map = folium.Map(location=[lat, lon], zoom_start=20)
  folium.Marker([lat, lon]).add_to(map)
  folium.CircleMarker([lat, lon],
                      radius=40
                     ).add_to(map)
  
  map
  </code></pre>
  
  <p>I have seen a number of places where it states that <code>radius=40</code> should show a 40 meter radius around the marker.</p>
  
  <p>The result of this code is:</p>
  
  <p><a href="https://i.stack.imgur.com/iIwwv.png" rel="noreferrer"><img src="https://i.stack.imgur.com/iIwwv.png" alt="enter image description here"></a></p>
  
  <p>But if I change the zoom to <code>zoom_start=5</code> I get a wider view but a circle of the same size.  This is not a 40 meter radius around the point.</p>
  
  <p><a href="https://i.stack.imgur.com/o3gpI.png" rel="noreferrer"><img src="https://i.stack.imgur.com/o3gpI.png" alt="enter image description here"></a></p>
  
  <p>Any idea how this works?  How do I show a 40m radius?</p>