PHP filesize Function
PHP filesize function tutorial shows how to get file sizes in PHP. Learn filesize with practical examples.
PHP filesize Function
last modified April 3, 2025
The PHP filesize function returns the size of a file in bytes. It’s useful for checking file sizes before processing or displaying them.
Basic Definition
The filesize function returns the size of the specified file. It takes one parameter: the filename or path to the file.
Syntax: filesize(string $filename): int|false. Returns file size in bytes or false on failure. The result is cached; use clearstatcache() for updated results.
Basic filesize Example
This shows the simplest usage of filesize to get a file’s size.
basic_filesize.php
<?php
declare(strict_types=1);
$filename = “example.txt”; $size = filesize($filename);
echo “File size: $size bytes”; // Outputs size in bytes
This gets the size of “example.txt” in bytes. The function requires the file to exist and be accessible to work properly.
Formatting File Size
We can format the raw byte count into a human-readable format.
format_size.php
<?php
declare(strict_types=1);
function formatSize(int $bytes): string { $units = [‘B’, ‘KB’, ‘MB’, ‘GB’, ‘TB’]; $index = 0;
while ($bytes >= 1024 && $index < 4) {
$bytes /= 1024;
$index++;
}
return round($bytes, 2) . ' ' . $units[$index];
}
$filename = “largefile.zip”; $size = filesize($filename);
echo “File size: " . formatSize($size);
This converts bytes to appropriate units (KB, MB, etc.). The function handles files of any size by dynamically selecting the best unit.
Checking File Existence
It’s good practice to check if a file exists before getting its size.
check_existence.php
<?php
declare(strict_types=1);
$filename = “nonexistent.txt”;
if (file_exists($filename)) { $size = filesize($filename); echo “File size: $size bytes”; } else { echo “File does not exist”; }
This prevents errors when trying to get the size of non-existent files. Always verify file existence before operations to avoid warnings.
Remote File Size
For remote files, we need a different approach as filesize doesn’t work with HTTP URLs.
remote_file.php
<?php
declare(strict_types=1);
function getRemoteFileSize(string $url): ?int { $headers = get_headers($url, true);
if ($headers && isset($headers['Content-Length'])) {
return (int)$headers['Content-Length'];
}
return null;
}
$fileUrl = “https://example.com/largefile.pdf"; $size = getRemoteFileSize($fileUrl);
echo $size ? “Remote file size: $size bytes” : “Size unavailable”;
This uses HTTP headers to get remote file sizes. Note that not all servers provide Content-Length headers for all files.
Directory Size Calculation
We can calculate total size of all files in a directory recursively.
directory_size.php
<?php
declare(strict_types=1);
function getDirectorySize(string $path): int { $size = 0; $files = new RecursiveIteratorIterator( new RecursiveDirectoryIterator($path) );
foreach ($files as $file) {
if ($file->isFile()) {
$size += $file->getSize();
}
}
return $size;
}
$dir = “/path/to/directory”; $totalSize = getDirectorySize($dir);
echo “Directory size: " . formatSize($totalSize);
This recursively calculates the total size of all files in a directory. It uses PHP’s SPL iterators for efficient directory traversal.
Best Practices
-
Error Handling: Always check if files exist and are readable.
-
Caching: Use clearstatcache() if file sizes might change.
-
Memory: Be careful with very large files on 32-bit systems.
-
Permissions: Ensure proper file permissions for access.
Source
This tutorial covered the PHP filesize function with practical examples showing its usage in different scenarios.
Author
My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.
