diff --git a/app/models/ticket_purchase.rb b/app/models/ticket_purchase.rb
index 07fb7e16..d1c370c4 100644
--- a/app/models/ticket_purchase.rb
+++ b/app/models/ticket_purchase.rb
@@ -18,6 +18,8 @@ class TicketPurchase < ActiveRecord::Base
   scope :by_conference, ->(conference) { where(conference_id: conference.id) }
   scope :by_user, ->(user) { where(user_id: user.id) }
 
+  after_create :set_week
+
   def self.purchase(conference, user, purchases)
     errors = []
     ActiveRecord::Base.transaction do
@@ -59,3 +61,10 @@ class TicketPurchase < ActiveRecord::Base
     purchase
   end
 end
+
+private
+
+def set_week
+  self.week = created_at.strftime('%W')
+  save!
+end
diff --git a/db/migrate/20170419132148_add_week_to_ticket_purchases.rb b/db/migrate/20170419132148_add_week_to_ticket_purchases.rb
new file mode 100644
index 00000000..0862eb16
--- /dev/null
+++ b/db/migrate/20170419132148_add_week_to_ticket_purchases.rb
@@ -0,0 +1,15 @@
+class AddWeekToTicketPurchases < ActiveRecord::Migration
+  class TmpTicketPurchase < ActiveRecord::Base
+    self.table_name = 'ticket_purchases'
+  end
+
+  def change
+    add_column :ticket_purchases, :week, :integer
+
+    TmpTicketPurchase.reset_column_information
+    TmpTicketPurchase.find_each do |purchase|
+      purchase.week = purchase.created_at ? purchase.created_at.strftime('%W') : 0
+      purchase.save!
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index ab95b4dc..5d74950a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170302145716) do
+ActiveRecord::Schema.define(version: 20170419132148) do
 
   create_table "ahoy_events", force: :cascade do |t|
     t.uuid     "visit_id",   limit: 16
@@ -447,6 +447,7 @@ ActiveRecord::Schema.define(version: 20170302145716) do
     t.integer  "quantity",      default: 1
     t.integer  "user_id"
     t.integer  "payment_id"
+    t.integer  "week"
   end
 
   create_table "tickets", force: :cascade do |t|