MongodbHow-ToBeginner · 3 min read

How to Use $lt and $lte in MongoDB Queries

In MongoDB, use $lt to find documents where a field's value is less than a specified value, and $lte to find documents where the field's value is less than or equal to a specified value. These operators are used inside query objects to filter data based on numeric or date comparisons.

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Syntax

The $lt and $lte operators are used in MongoDB queries to compare field values.

$lt: Matches values less than the specified value.
$lte: Matches values less than or equal to the specified value.

They are used inside a query object with the field name as the key.

json

{
  "field": { "$lt": value }
}

{
  "field": { "$lte": value }
}

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Example

This example shows how to find products priced less than 50 and products priced less than or equal to 50 in a collection named products.

javascript

db.products.insertMany([
  { name: "Pen", price: 20 },
  { name: "Notebook", price: 50 },
  { name: "Backpack", price: 80 }
])

// Find products with price less than 50
const lessThan50 = db.products.find({ price: { $lt: 50 } }).toArray()

// Find products with price less than or equal to 50
const lessThanOrEqual50 = db.products.find({ price: { $lte: 50 } }).toArray()

print('Products with price < 50:', JSON.stringify(lessThan50))
print('Products with price <= 50:', JSON.stringify(lessThanOrEqual50))

Output

Products with price < 50: [{"_id":"...","name":"Pen","price":20}] Products with price <= 50: [{"_id":"...","name":"Pen","price":20},{"_id":"...","name":"Notebook","price":50}]

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Common Pitfalls

Common mistakes when using $lt and $lte include:

Using them outside of a field query object, which causes syntax errors.
Confusing $lt (less than) with $lte (less than or equal to).
Applying these operators on non-comparable data types like strings without understanding lexicographical order.

javascript

/* Wrong: Using $lt without field key */
db.products.find({ $lt: 50 })

/* Right: Use $lt inside field query */
db.products.find({ price: { $lt: 50 } })

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Quick Reference

Operator	Meaning	Example
$lt	Less than	{ price: { $lt: 100 } }
$lte	Less than or equal to	{ price: { $lte: 100 } }

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Key Takeaways

Use $lt to find documents where a field is less than a value.

Use $lte to find documents where a field is less than or equal to a value.

Always place $lt and $lte inside the field's query object.

Be careful not to confuse $lt (less than) with $lte (less than or equal).

These operators work well with numbers and dates but be cautious with strings.