--- /dev/null
+++ b/app/api/service/ScaleDateTimeResponse.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace app\api\service;
+
+use app\common\database\Dm;
+
+/** Match the two scale services' MySQL DATETIME(0) measured_at response only. */
+final class ScaleDateTimeResponse
+{
+    public static function measuredAt($value, $connection)
+    {
+        if (!($connection instanceof Dm) || !is_string($value)
+            || !preg_match('/^([1-9]\d{3})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})\.0{1,6}$/D', $value, $parts)) {
+            return $value;
+        }
+
+        if (!checkdate((int)$parts[2], (int)$parts[3], (int)$parts[1])
+            || (int)$parts[4] > 23 || (int)$parts[5] > 59 || (int)$parts[6] > 59) {
+            return $value;
+        }
+
+        return substr($value, 0, 19);
+    }
+}
--- a/app/api/service/WellandScale.php
+++ b/app/api/service/WellandScale.php
@@ -326,7 +326,7 @@
 
         return [
             'session_id' => $sessionId,
-            'measured_at' => $session['start_time'] ?? null,
+            'measured_at' => ScaleDateTimeResponse::measuredAt($session['start_time'] ?? null, $db),
             'vendor' => $session['vendor'] ?? 'welland',
             'device_type' => $session['device_type'] ?? 'body_scale',
             'algorithm_vendor' => $algoVendor,
@@ -421,7 +421,7 @@
 
         return [
             'session_id' => $sessionId,
-            'measured_at' => $session['start_time'] ?? null,
+            'measured_at' => ScaleDateTimeResponse::measuredAt($session['start_time'] ?? null, $db),
             'vendor' => $session['vendor'] ?? 'welland',
             'device_type' => $session['device_type'] ?? 'body_scale',
             'algorithm_vendor' => $algoVendor,
--- a/app/api/service/YunkangbaoScale.php
+++ b/app/api/service/YunkangbaoScale.php
@@ -251,7 +251,7 @@
 
         return [
             'session_id' => $sessionId,
-            'measured_at' => $session['start_time'] ?? null,
+            'measured_at' => ScaleDateTimeResponse::measuredAt($session['start_time'] ?? null, $db),
             'vendor' => $session['vendor'] ?? 'yunkangbao',
             'device_type' => $session['device_type'] ?? 'body_scale',
             'algorithm_vendor' => $algoVendor,