diff --git a/classes/admin.php b/classes/admin.php
index e0f38e9e..366490fb 100644
--- a/classes/admin.php
+++ b/classes/admin.php
@@ -1,6 +1,7 @@
 <?php
 namespace Grav\Plugin;
 
+use DateTime;
 use Grav\Common\Data;
 use Grav\Common\File\CompiledYamlFile;
 use Grav\Common\GPM\GPM;
@@ -1013,11 +1014,72 @@ class Admin
         return $lookup;
     }
 
+    /**
+     * Guest date format based on euro/US
+     *
+     * @param $date
+     * @return string
+     */
+    public function guessDateFormat($date)
+    {
+        static $guess;
+
+        if (!$guess) {
+            if (Utils::contains($date, '/')) {
+                if ($this->validateDate($date, 'm/d/Y H:i')) {
+                    $guess = 'm/d/Y H:i';
+                } elseif ($this->validateDate($date, 'm/d/y H:i')) {
+                    $guess = 'm/d/y H:i';
+                } elseif ($this->validateDate($date, 'm/d/Y G:i')) {
+                    $guess = 'm/d/Y G:i';
+                } elseif ($this->validateDate($date, 'm/d/y G:i')) {
+                    $guess = 'm/d/y G:i';
+                } elseif ($this->validateDate($date, 'm/d/Y h:ia')) {
+                    $guess = 'm/d/Y h:ia';
+                } elseif ($this->validateDate($date, 'm/d/y h:ia')) {
+                    $guess = 'm/d/y h:ia';
+                } elseif ($this->validateDate($date, 'm/d/Y g:ia')) {
+                    $guess = 'm/d/Y g:ia';
+                } elseif ($this->validateDate($date, 'm/d/y g:ia')) {
+                    $guess = 'm/d/y g:ia';
+                }
+            } elseif (Utils::contains($date, '-')) {
+                if ($this->validateDate($date, 'd-m-Y H:i')) {
+                    $guess = 'd-m-Y H:i';
+                } elseif ($this->validateDate($date, 'd-m-y H:i')) {
+                    $guess = 'd-m-y H:i';
+                } elseif ($this->validateDate($date, 'd-m-Y G:i')) {
+                    $guess = 'd-m-Y G:i';
+                } elseif ($this->validateDate($date, 'd-m-y G:i')) {
+                    $guess = 'd-m-y G:i';
+                } elseif ($this->validateDate($date, 'd-m-Y h:ia')) {
+                    $guess = 'd-m-Y h:ia';
+                } elseif ($this->validateDate($date, 'd-m-y h:ia')) {
+                    $guess = 'd-m-y h:ia';
+                } elseif ($this->validateDate($date, 'd-m-Y g:ia')) {
+                    $guess = 'd-m-Y g:ia';
+                } elseif ($this->validateDate($date, 'd-m-y g:ia')) {
+                    $guess = 'd-m-y g:ia';
+                }
+            } else {
+                $guess = 'd-m-Y H:i';
+            }
+        }
+
+        return $guess;
+    }
+
+    public function validateDate($date, $format)
+    {
+        $d = DateTime::createFromFormat($format, $date);
+        return $d && $d->format($format) == $date;
+    }
+
     /**
      * @param string $php_format
      * @return string
      */
-    function dateformatToMomentJS($php_format)
+    public function dateformatToMomentJS($php_format)
     {
         $SYMBOLS_MATCHING = array(
             // Day
diff --git a/themes/grav/templates/forms/fields/datetime/datetime.html.twig b/themes/grav/templates/forms/fields/datetime/datetime.html.twig
index e93d4409..657c35d2 100644
--- a/themes/grav/templates/forms/fields/datetime/datetime.html.twig
+++ b/themes/grav/templates/forms/fields/datetime/datetime.html.twig
@@ -1,17 +1,18 @@
 {% extends "forms/field.html.twig" %}
 
-{% set default_php_dateformat = "d-m-Y H:i" %}
-
-{% if not config.system.pages.dateformat.default and value %}
-    {% if value|split('/')|count %}{% set default_php_dateformat = 'm/d/Y H:i' %}{% endif %}
-{% endif %}
-
-{% set php_dateformat = config.system.pages.dateformat.default ?: default_php_dateformat %}
+{% set default_php_dateformat = admin.guessDateFormat(value) %}
+{% set php_dateformat = admin.page.dateformat ?: config.system.pages.dateformat.default ?: default_php_dateformat %}
 {% set js_dateformat = admin.dateformatToMomentJS(php_dateformat) %}
 {% set value = (value is null ? field.default : value) %}
 {% set value = (value is null ? value : value|date(php_dateformat)) %}
 
 {% block input %}
+    {{ dump(default_php_dateformat) }}
+    {{ dump(admin.page.dateformat) }}
+    {{ dump(config.system.pages.dateformat.default) }}
+    {{ dump(php_dateformat) }}
+    {{ dump(js_dateformat) }}
+    {{ dump('======') }}
 <div class="form-input-wrapper datetime-picker-wrapper {{ field.size }}">
     <input
             name="{{ (scope ~ field.name)|fieldName }}"