Use d3.geo.area

js/id/core/entity.js

@@ -36,11 +36,6 @@ iD.Entity.key = function(entity) {
     return entity.id + 'v' + (entity.v || 0);
 };
 
-iD.Entity.areaPath = d3.geo.path()
-    .projection(d3.geo.mercator()
-        .scale(12016420.517592335)
-        .precision(0));
-
 iD.Entity.prototype = {
     tags: {},
 
@@ -107,12 +102,9 @@ iD.Entity.prototype = {
             resolver.parentRelations(this).length > 0;
     },
 
-    // Returns the (possibly negative) area of the entity in square pixels at an
-    // arbitrary unspecified zoom level -- so basically, only useful for relative
-    // comparisons.
     area: function(resolver) {
         return resolver.transient(this, 'area', function() {
-            return iD.Entity.areaPath.area(this.asGeoJSON(resolver, true));
+            return d3.geo.area(this.asGeoJSON(resolver, true));
         });
     },