If you’re receiving error Msg 8115, Level 16, Arithmetic overflow error converting expression to data type int in SQL Server, it could be that you’re performing a calculation that results in an out of range value.

This can happen when you use a function such as SUM() on a column, and the calculation results in a value that’s outside the range of the column’s type.

Example of the Error

Here’s an example of code that produces the error:

SELECT SUM(bank_balance) 
FROM accounts;

Result:

Msg 8115, Level 16, State 2, Line 1
Arithmetic overflow error converting expression to data type int.

In this case I used the SUM() function to get the sum of the bank_balance column, which has a data type of int.

The error occurred because the result of the calculation is outside the range of the int data type.

Here’s all the data in my table:

SELECT bank_balance 
FROM accounts;

Result:

+----------------+
| bank_balance   |
|----------------|
| 1300000000     |
| 1200000000     |
| 800500000      |
+----------------+

Those are some big bank balances… and adding the three of them results in a larger number than an int can handle (the int range is -2,147,483,648 to 2,147,483,647).

The Solution

We can deal with this error by converting the int column to a bigint when we run the query:

SELECT SUM(CAST(bank_balance AS bigint)) 
FROM Accounts;

Result:

3300500000

This time it worked.

You could also change the data type of the actual column for a more permanent solution.

In case you’re wondering, the bigint range is -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

Same Error in Different Scenarios

The same error (Msg 8115) can also occur (with a slightly different error message) when you try to explicitly convert between data types and the original value is outside the range of the new type. See Fix “Arithmetic overflow error converting int to data type numeric” in SQL Server to fix this.

The same error (Msg 8115) can also occur (with a slightly different error message) when you try to insert data into a table when its IDENTITY column has reached its data type’s limit. See Fix: “Arithmetic overflow error converting IDENTITY to data type…” in SQL Server for how to fix this.