diff --git a/gallery_dl/extractor/common.py b/gallery_dl/extractor/common.py
index 048e0a34..2533ae5a 100644
--- a/gallery_dl/extractor/common.py
+++ b/gallery_dl/extractor/common.py
@@ -174,8 +174,7 @@ class Extractor():
         elif until:
             if isinstance(until, datetime.datetime):
                 # convert to UTC timestamp
-                epoch = datetime.datetime(1970, 1, 1)
-                until = (until - epoch) / datetime.timedelta(0, 1)
+                until = (until - util.EPOCH) / util.SECOND
             else:
                 until = float(until)
             seconds = until - now
diff --git a/gallery_dl/util.py b/gallery_dl/util.py
index 12896e6e..f6827f9f 100644
--- a/gallery_dl/util.py
+++ b/gallery_dl/util.py
@@ -145,6 +145,14 @@ def to_string(value):
     return str(value)
 
 
+def to_timestamp(dt):
+    """Convert naive datetime to UTC timestamp string"""
+    try:
+        return str((dt - EPOCH) // SECOND)
+    except Exception:
+        return ""
+
+
 def dump_json(obj, fp=sys.stdout, ensure_ascii=True, indent=4):
     """Serialize 'obj' as JSON and write it to 'fp'"""
     json.dump(
@@ -370,6 +378,8 @@ class UniversalNone():
 
 
 NONE = UniversalNone()
+EPOCH = datetime.datetime(1970, 1, 1)
+SECOND = datetime.timedelta(0, 1)
 WINDOWS = (os.name == "nt")
 SENTINEL = object()
 SPECIAL_EXTRACTORS = {"oauth", "recursive", "test"}
@@ -536,6 +546,7 @@ class Formatter():
     - "d": calls text.parse_timestamp
     - "U": calls urllib.parse.unquote
     - "S": calls util.to_string()
+    - "T": calls util.to_timestamü()
     - Example: {f!l} -> "example"; {f!u} -> "EXAMPLE"
 
     Extra Format Specifiers:
@@ -566,6 +577,7 @@ class Formatter():
         "c": str.capitalize,
         "C": string.capwords,
         "t": str.strip,
+        "T": to_timestamp,
         "d": text.parse_timestamp,
         "U": urllib.parse.unquote,
         "S": to_string,
diff --git a/test/test_util.py b/test/test_util.py
index d90d5adc..0b61d813 100644
--- a/test/test_util.py
+++ b/test/test_util.py
@@ -271,6 +271,7 @@ class TestFormatter(unittest.TestCase):
         "s": " \n\r\tSPACE    ",
         "u": "%27%3C%20/%20%3E%27",
         "t": 1262304000,
+        "dt": datetime.datetime(2010, 1, 1),
         "name": "Name",
         "title1": "Title",
         "title2": "",
@@ -295,6 +296,7 @@ class TestFormatter(unittest.TestCase):
         self._run_test("{n!S}", "")
         self._run_test("{t!d}", datetime.datetime(2010, 1, 1))
         self._run_test("{t!d:%Y-%m-%d}", "2010-01-01")
+        self._run_test("{dt!T}", "1262304000")
 
         with self.assertRaises(KeyError):
             self._run_test("{a!q}", "hello world")
@@ -601,6 +603,11 @@ class TestOther(unittest.TestCase):
         self.assertEqual(f(["a", "b", "c"]), "a, b, c")
         self.assertEqual(f([1, 2, 3]), "1, 2, 3")
 
+    def test_to_timestamp(self, f=util.to_timestamp):
+        self.assertEqual(f(util.EPOCH), "0")
+        self.assertEqual(f(datetime.datetime(2010, 1, 1)), "1262304000")
+        self.assertEqual(f(None), "")
+
     def test_universal_none(self):
         obj = util.NONE