diff --git a/app/__init__.py b/app/__init__.py
index 967d05efe..af0b5253d 100644
--- a/app/__init__.py
+++ b/app/__init__.py
@@ -7,7 +7,6 @@ from time import monotonic
 
 import dateutil
 import itertools
-import pytz
 import ago
 from flask import (
     Flask,
@@ -58,6 +57,8 @@ from app.notify_client.organisations_client import OrganisationsClient
 from app.notify_client.models import AnonymousUser
 from app.notify_client.letter_jobs_client import LetterJobsClient
 
+from app.utils import gmt_timezones
+
 login_manager = LoginManager()
 csrf = CsrfProtect()
 
@@ -215,12 +216,6 @@ def syntax_highlight_json(code):
     return Markup(highlight(code, JavascriptLexer(), HtmlFormatter(noclasses=True)))
 
 
-def gmt_timezones(date):
-    date = dateutil.parser.parse(date)
-    forced_utc = date.replace(tzinfo=pytz.utc)
-    return forced_utc.astimezone(pytz.timezone('Europe/London'))
-
-
 def format_datetime(date):
     return '{} at {}'.format(
         format_date(date),
diff --git a/app/utils.py b/app/utils.py
index 62daaeab9..b4aafc0d9 100644
--- a/app/utils.py
+++ b/app/utils.py
@@ -1,10 +1,12 @@
 import re
 import csv
+import pytz
 from io import StringIO
 from os import path
 from functools import wraps
 import unicodedata
 from datetime import datetime, timedelta, timezone
+from dateutil import parser
 
 import dateutil
 import ago
@@ -324,3 +326,25 @@ def get_time_left(created_at):
 
 def email_or_sms_not_enabled(template_type, permissions):
     return (template_type in ['email', 'sms']) and (template_type not in permissions)
+
+
+def get_estimated_delivery_date_for_letters(upload_time):
+
+    # shift anything after 5pm to the next day
+    processing_day = gmt_timezones(upload_time) + timedelta(hours=(7))
+
+    return tuple(
+        processing_day + timedelta(days=days)
+        for days in {
+            'Wednesday': (3, 5),
+            'Thursday': (4, 5),
+            'Friday': (5, 6),
+            'Saturday': (4, 5),
+        }.get(processing_day.strftime('%A'), (3, 4))
+    )
+
+
+def gmt_timezones(date):
+    date = dateutil.parser.parse(date)
+    forced_utc = date.replace(tzinfo=pytz.utc)
+    return forced_utc.astimezone(pytz.timezone('Europe/London'))
diff --git a/tests/app/test_utils.py b/tests/app/test_utils.py
index e1fa0e4f3..abced152a 100644
--- a/tests/app/test_utils.py
+++ b/tests/app/test_utils.py
@@ -11,7 +11,8 @@ from app.utils import (
     generate_notifications_csv,
     generate_previous_dict,
     generate_next_dict,
-    Spreadsheet
+    Spreadsheet,
+    get_estimated_delivery_date_for_letters,
 )
 
 from tests import notification_json, single_notification_json
@@ -154,3 +155,45 @@ def test_generate_notifications_csv_calls_twice_if_next_link(mocker):
     # mock_calls[0][2] is the kwargs from first call
     assert mock_get_notifications.mock_calls[0][2]['page'] == 1
     assert mock_get_notifications.mock_calls[1][2]['page'] == 2
+
+
+@pytest.mark.parametrize('upload_time, expected_estimate', [
+
+    # BST
+    # ==================================================================
+    #  First thing Monday
+    ('2017-07-10 00:00:01', ('Thursday', 'Friday')),
+    #  Monday at 16:59 BST
+    ('2017-07-10 15:59:59', ('Thursday', 'Friday')),
+    #  Monday at 17:00 BST
+    ('2017-07-10 16:00:01', ('Friday', 'Saturday')),
+    #  Tuesday before 17:00 BST
+    ('2017-07-11 12:00:00', ('Friday', 'Saturday')),
+    #  Wednesday before 17:00 BST
+    ('2017-07-12 12:00:00', ('Saturday', 'Monday')),
+    #  Thursday before 17:00 BST
+    ('2017-07-13 12:00:00', ('Monday', 'Tuesday')),
+    #  Friday anytime
+    ('2017-07-14 00:00:00', ('Wednesday', 'Thursday')),
+    ('2017-07-14 12:00:00', ('Wednesday', 'Thursday')),
+    ('2017-07-14 22:00:00', ('Wednesday', 'Thursday')),
+    #  Saturday anytime
+    ('2017-07-14 12:00:00', ('Wednesday', 'Thursday')),
+    #  Sunday before 1700 BST
+    ('2017-07-15 15:59:59', ('Wednesday', 'Thursday')),
+    #  Sunday after 17:00 BST
+    ('2017-07-16 16:00:01', ('Thursday', 'Friday')),
+
+    # GMT
+    # ==================================================================
+    #  Monday at 16:59 GMT
+    ('2017-01-02 16:59:59', ('Thursday', 'Friday')),
+    #  Monday at 17:00 GMT
+    ('2017-01-02 17:00:01', ('Friday', 'Saturday')),
+
+])
+def test_get_estimated_delivery_date_for_letter(upload_time, expected_estimate):
+    assert tuple(
+        day.strftime('%A')
+        for day in get_estimated_delivery_date_for_letters(upload_time)
+    ) == expected_estimate