diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 460fb54da9..28d7d76de5 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -37,6 +37,7 @@ Yii Framework 2 Change Log
 - Bug #19655: Fix `LinkPager::getPageRange` when `maxButtons` is 2 (max-s-lab)
 - Enh #20539: Update minimum PHP version requirement from `7.3` to `7.4` (terabytesoftw)
 - Bug #20541: Remove deprecated caching components: `XCache` and `ZendDataCache`, and update related tests and documentation (terabytesoftw)
+- Enh #19526: Add the `convertIniSizeToBytes` method to `BaseStringHelper` (max-s-lab)
 
 
 2.0.53 June 27, 2025
diff --git a/framework/helpers/BaseStringHelper.php b/framework/helpers/BaseStringHelper.php
index 5854e29766..a1ed907e98 100644
--- a/framework/helpers/BaseStringHelper.php
+++ b/framework/helpers/BaseStringHelper.php
@@ -52,6 +52,30 @@ class BaseStringHelper
         return mb_substr((string)$string, $start, $length, '8bit');
     }
 
+    /**
+     * Converts php.ini style size to bytes.
+     *
+     * @param string $string php.ini style size. Examples: `512M`, `1024K`, `1G`, `256`.
+     * @return int the number of bytes equivalent to the specified string.
+     * @since 2.0.54
+     */
+    public static function convertIniSizeToBytes($string)
+    {
+        switch (substr($string, -1)) {
+            case 'M':
+            case 'm':
+                return (int) $string * 1048576;
+            case 'K':
+            case 'k':
+                return (int) $string * 1024;
+            case 'G':
+            case 'g':
+                return (int) $string * 1073741824;
+            default:
+                return (int) $string;
+        }
+    }
+
     /**
      * Returns the trailing name component of a path.
      * This method is similar to the php function `basename()` except that it will
diff --git a/framework/validators/FileValidator.php b/framework/validators/FileValidator.php
index 28a2df0fa3..4d5a5dfd26 100644
--- a/framework/validators/FileValidator.php
+++ b/framework/validators/FileValidator.php
@@ -325,8 +325,8 @@ class FileValidator extends Validator
     public function getSizeLimit()
     {
         // Get the lowest between post_max_size and upload_max_filesize, log a warning if the first is < than the latter
-        $limit = $this->sizeToBytes(ini_get('upload_max_filesize'));
-        $postLimit = $this->sizeToBytes(ini_get('post_max_size'));
+        $limit = StringHelper::convertIniSizeToBytes(ini_get('upload_max_filesize'));
+        $postLimit = StringHelper::convertIniSizeToBytes(ini_get('post_max_size'));
         if ($postLimit > 0 && $postLimit < $limit) {
             Yii::warning('PHP.ini\'s \'post_max_size\' is less than \'upload_max_filesize\'.', __METHOD__);
             $limit = $postLimit;
@@ -351,29 +351,6 @@ class FileValidator extends Validator
         return !($value instanceof UploadedFile) || $value->error == UPLOAD_ERR_NO_FILE;
     }
 
-    /**
-     * Converts php.ini style size to bytes.
-     *
-     * @param string $sizeStr $sizeStr
-     * @return int
-     */
-    private function sizeToBytes($sizeStr)
-    {
-        switch (substr($sizeStr, -1)) {
-            case 'M':
-            case 'm':
-                return (int) $sizeStr * 1048576;
-            case 'K':
-            case 'k':
-                return (int) $sizeStr * 1024;
-            case 'G':
-            case 'g':
-                return (int) $sizeStr * 1073741824;
-            default:
-                return (int) $sizeStr;
-        }
-    }
-
     /**
      * Checks if given uploaded file have correct type (extension) according current validator settings.
      * @param UploadedFile $file
diff --git a/tests/framework/helpers/StringHelperTest.php b/tests/framework/helpers/StringHelperTest.php
index 5f222ec4e7..8c28a4d561 100644
--- a/tests/framework/helpers/StringHelperTest.php
+++ b/tests/framework/helpers/StringHelperTest.php
@@ -536,4 +536,25 @@ class StringHelperTest extends TestCase
             ['من صالح هاشمی هستم', 'من ', ' هستم', 'صالح هاشمی'], // other languages
         ];
     }
+
+    /**
+     * @dataProvider provideConvertIniSizeToBytesData
+     */
+    public function testConvertIniSizeToBytes(string $string, int $expectedResult): void
+    {
+        $this->assertEquals($expectedResult, StringHelper::convertIniSizeToBytes($string));
+    }
+
+    public static function provideConvertIniSizeToBytesData(): array
+    {
+        return [
+            ['1024', 1024],
+            ['512K', 524288],
+            ['512k', 524288],
+            ['128M', 134217728],
+            ['128m', 134217728],
+            ['2G', 2147483648],
+            ['2g', 2147483648],
+        ];
+    }
 }
diff --git a/tests/framework/validators/FileValidatorTest.php b/tests/framework/validators/FileValidatorTest.php
index 9e05edf4d2..0009db6dbf 100644
--- a/tests/framework/validators/FileValidatorTest.php
+++ b/tests/framework/validators/FileValidatorTest.php
@@ -9,6 +9,7 @@ namespace yiiunit\framework\validators;
 
 use Yii;
 use yii\helpers\FileHelper;
+use yii\helpers\StringHelper;
 use yii\validators\FileValidator;
 use yii\web\UploadedFile;
 use yiiunit\data\validators\models\FakedValidationModel;
@@ -78,7 +79,11 @@ class FileValidatorTest extends TestCase
 
     public function testGetSizeLimit()
     {
-        $size = min($this->sizeToBytes(ini_get('upload_max_filesize')), $this->sizeToBytes(ini_get('post_max_size')));
+        $size = min(
+            StringHelper::convertIniSizeToBytes(ini_get('upload_max_filesize')),
+            StringHelper::convertIniSizeToBytes(ini_get('post_max_size'))
+        );
+
         $val = new FileValidator();
         $this->assertEquals($size, $val->getSizeLimit());
         $val->maxSize = $size + 1; // set and test if value is overridden
@@ -91,23 +96,6 @@ class FileValidatorTest extends TestCase
         $this->assertSame($_POST['MAX_FILE_SIZE'], $val->getSizeLimit());
     }
 
-    protected function sizeToBytes($sizeStr)
-    {
-        switch (substr($sizeStr, -1)) {
-            case 'M':
-            case 'm':
-                return (int) $sizeStr * 1048576;
-            case 'K':
-            case 'k':
-                return (int) $sizeStr * 1024;
-            case 'G':
-            case 'g':
-                return (int) $sizeStr * 1073741824;
-            default:
-                return (int) $sizeStr;
-        }
-    }
-
     public function testValidateAttributeMultiple()
     {
         $val = new FileValidator([
@@ -370,7 +358,7 @@ class FileValidatorTest extends TestCase
             } else {
                 $size = isset($param['size']) ? $param['size'] : random_int(
                     1,
-                    $this->sizeToBytes(ini_get('upload_max_filesize'))
+                    StringHelper::convertIniSizeToBytes(ini_get('upload_max_filesize'))
                 );
             }
             $type = isset($param['type']) ? $param['type'] : 'text/plain';