MongoDB $lte Operator

Example 1 — Sample Data

Imagine three students: Asha (85), Ben (72), and Cara (80—exactly on the line). We save them in students.

db.students.insertMany([
  { _id: 1, name: "Asha", score: 85 },
  { _id: 2, name: "Ben", score: 72 },
  { _id: 3, name: "Cara", score: 80 }
]);

How the Data Is Stored in MongoDB

After the insert, MongoDB keeps three documents in students. Run find() to see them:

db.students.find()

[
  { _id: 1, name: "Asha", score: 85 },
  { _id: 2, name: "Ben", score: 72 },
  { _id: 3, name: "Cara", score: 80 }
]

Read those documents like this:

Threshold line at 80:

  Ben 72 ..... Cara 80 ..... Asha 85
                    |
              score ≤ 80 ?

  Ben  → yes
  Cara → yes  (equals count)
  Asha → no

How It Works

1. Insert once. insertMany adds three student documents to students.
2. Include the boundary. Cara’s score is exactly 80—key for $lte vs $lt.
3. find() shows all rows. The next example keeps scores at or below 80.

Example 2 — Filter with $lte

Goal: return students whose score is less than or equal to 80.

db.students.find({
  score: { $lte: 80 }
});

[
  { _id: 2, name: "Ben", score: 72 },
  { _id: 3, name: "Cara", score: 80 }
]

How It Works

1. Apply a filter. { score: { $lte: 80 } } means “score must be ≤ 80”.
2. Test each document. Ben 72 and Cara 80 pass; Asha 85 fails.
3. Equals count. Cara stays—that is the difference from $lt.

Example 3 — Boolean Expression

Same students, but keep every document and add an atOrBelow boolean with the aggregation form of $lte.

db.students.aggregate([
  {
    $addFields: {
      atOrBelow: {
        $lte: ["$score", 80]
      }
    }
  }
]);

[
  { _id: 1, name: "Asha", score: 85, atOrBelow: false },
  { _id: 2, name: "Ben", score: 72, atOrBelow: true },
  { _id: 3, name: "Cara", score: 80, atOrBelow: true }
]

How It Works

1. Same stored documents. Still using Asha, Ben, and Cara from Example 1.
2. Compare as an expression. { $lte: ["$score", 80] } returns a boolean per document.
3. Nothing is dropped. All three rows stay; only the atOrBelow flag differs.