What is strtotime() in PHP?

• strtotime() converts an English textual date/time description into a Unix timestamp (i.e., a number of seconds since January 1, 1970).
• It’s very useful when you want to manipulate or format dates easily.

Syntax:

strtotime(string $datetime, int|null $baseTimestamp = null): int|false

• $datetime → The date/time text you want to parse.

• $baseTimestamp → (Optional) A timestamp to base the calculation on.

• Returns: the timestamp on success, or false if parsing fails.

Simple Examples

Example 1: Current time

echo strtotime("now");
// Outputs: Current timestamp (e.g., 1714162812)

Example 2: Specific date

echo strtotime("15 August 2025");
// Outputs: 1755235200

Example 3: Relative dates

echo strtotime("+1 day");      // Tomorrow
echo strtotime("+1 week");     // Next week
echo strtotime("+1 month");    // Next month
echo strtotime("-2 days");     // Two days ago

Example 4: Combine with date()

echo date('Y-m-d', strtotime("+5 days"));
// Outputs: 2025-05-02 (if today is 2025-04-27)

Example 5: Using a base timestamp

$base = strtotime('2025-01-01');
echo date('Y-m-d', strtotime('+10 days', $base));
// Outputs: 2025-01-11

Common use cases:

• Add or subtract days from a date.
• Convert a string input to a date for comparison.
• Schedule events.
• Format user inputted dates.

Important Points

• If strtotime() cannot understand the input, it returns false.
• Always validate the result before using it:

$timestamp = strtotime('invalid date');
if ($timestamp === false) {
    echo "Invalid date!";
} else {
    echo date('Y-m-d', $timestamp);
}