> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# $center (query predicate operator)

## Definition

The [`$center`](https://www.mongodb.com/docs/manual/reference/operator/query/center.md#mongodb-query-op.-center) operator specifies a circle for a [`$geoWithin`](https://www.mongodb.com/docs/manual/reference/operator/query/geowithin.md#mongodb-query-op.-geoWithin) query. The query returns legacy coordinate pairs that are within the bounds of the circle. The operator does *not* return GeoJSON objects.

To use the [`$center`](https://www.mongodb.com/docs/manual/reference/operator/query/center.md#mongodb-query-op.-center) operator, specify an array that contains:

- The grid coordinates of the circle's center point, and

- The circle's radius, as measured in the units used by the coordinate system.

```javascript
{
   <location field>: {
      $geoWithin: { $center: [ [ <x>, <y> ] , <radius> ] }
   }
}
```

**Important: If you use longitude and latitude, specify longitude first.**

## Behavior

The query calculates distances using flat (planar) geometry.

Applications can use [`$center`](https://www.mongodb.com/docs/manual/reference/operator/query/center.md#mongodb-query-op.-center) *without* having a geospatial index. However, geospatial indexes support much faster queries than the unindexed equivalents.

Only the [2d](https://www.mongodb.com/docs/manual/core/indexes/index-types/geospatial/2d.md#std-label-2d-index) geospatial index supports [`$center`.](https://www.mongodb.com/docs/manual/reference/operator/query/center.md#mongodb-query-op.-center)

## Example

The following example query returns all documents that have coordinates that exist within the circle centered on `[ -74, 40.74 ]` and with a radius of `10`:

```javascript
db.places.find(
   { loc: { $geoWithin: { $center: [ [-74, 40.74], 10 ] } } }
)
```