$toInt (Convert to 32-bit Integer)

Last updated: 2026-10-09

$toInt (Convert to 32-bit Integer)

$toInt converts a value to a 32-bit signed integer (BSON int). It accepts numbers, numeric strings and booleans; null stays null. Typical uses: normalizing integer strings from external systems or rounding floats to integers. Values outside the 32-bit range (about 2.1 billion) throw — use $toLong for big integers. Strings must be integer literals; a fractional string like '4.5' throws. It is the $convert shortcut for to: int.

📝 Syntax

{ $toInt: <expression> }

⚙️ Parameters

Returns：An int; null when the input is null

▶ Example

Run the commands below in your local mongosh (requires a running mongod):

// $toInt: parse a quantity string into an integer
db.orders.aggregate([
  { $project: {
      qty: { $toInt: '$qtyStr' }
  } }
])

Output：

{ '_id': 1, 'qty': 3 }

📌 Notes

• 32-bit range is about 2.1 billion; beyond it throws, so use $toLong for big numbers
• Strings must be integer literals; '4.5' throws
• true becomes 1 and false becomes 0

🏷️ Related Tags

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❓ FAQ

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