MySQL TIMESTAMPDIFF() Function

Syntax

TIMESTAMPDIFF(unit, datetime_expr1, datetime_expr2)

TIMESTAMPDIFF returns the integer difference between two datetime values in the requested unit.

Basic Example

SELECT TIMESTAMPDIFF(DAY, '2026-05-10', '2026-05-17') AS days_between;
-- Result: 7

Practical query example

SELECT session_id,
       TIMESTAMPDIFF(MINUTE, login_at, logout_at) AS session_minutes
FROM user_sessions;

Commonly used units

YEAR, MONTH, DAY, HOUR, MINUTE, SECOND

TIMESTAMPDIFF vs DATEDIFF

• Use DATEDIFF for day-level date comparisons.
• Use TIMESTAMPDIFF for hour/minute/second precision and explicit unit control.

When to use it

Use TIMESTAMPDIFF for session duration, SLA response windows, aging calculations, and elapsed-time analytics.

Common mistakes

• Forgetting the first unit argument.
• Reversing datetime arguments and getting negative results unexpectedly.
• Expecting decimals. TIMESTAMPDIFF returns whole integers in the selected unit.

Troubleshoot MySQL TIMESTAMPDIFF problems

Related SQL Functions

• MySQL DATEDIFF() Function
• MySQL DATE_ADD() Function
• MySQL DATE_SUB() Function
• MySQL DATE_FORMAT() Function
• MySQL NOW() Function
• MySQL CURDATE() Function

FAQ

Why is TIMESTAMPDIFF negative?

The function computes datetime_expr2 - datetime_expr1 in the unit you provide. Swap arguments if needed.

Does TIMESTAMPDIFF return fractional values?

No. It returns whole integers in the requested unit.

Can TIMESTAMPDIFF be used in WHERE clauses?

Yes, but test index-friendly alternatives for large tables if performance becomes a concern.