diff --git a/booking/models.py b/booking/models.py
index 42f7e45..5501e0f 100644
--- a/booking/models.py
+++ b/booking/models.py
@@ -50,6 +50,15 @@ class Duck(models.Model):
 
         return self.name
 
+    def age(self):
+        seconds_d = timezone.now() - self.donated_at
+        seconds = seconds_d.total_seconds()
+
+        if seconds < 0:
+            return -1
+
+        return seconds
+
 class DuckName(models.Model):
     """Model to hold name suggestions for Ducks"""
 
diff --git a/booking/tests.py b/booking/tests.py
index cb08550..ca8c133 100644
--- a/booking/tests.py
+++ b/booking/tests.py
@@ -1,4 +1,9 @@
 from django.test import TestCase, Client
+from django.utils import timezone
+
+import datetime
+
+from .models import Duck
 
 class FrontTest(TestCase):
     def setUp(self):
@@ -15,3 +20,8 @@ class FrontTest(TestCase):
     def test_disclaimer_page(self):
         response = self.client.get('/disclaimer.html')
         self.assertEqual(response.status_code, 200)
+
+class DuckAgeTest(TestCase):
+    def test_duck_is_from_the_future(self):
+        future_duck = Duck(donated_at = timezone.now() + datetime.timedelta(days = 2))
+        self.assertEqual(future_duck.age(), -1)