diff --git a/app/models/card.rb b/app/models/card.rb
index fb1025d4d..a509b4ff2 100644
--- a/app/models/card.rb
+++ b/app/models/card.rb
@@ -3,7 +3,7 @@ class Card < ApplicationRecord
     Golden, Mentions, Multistep, Pinnable, Postponable, Promptable,
     Readable, Searchable, Stallable, Statuses, Taggable, Triageable, Watchable
 
-  belongs_to :account, default: -> { Current.account }
+  belongs_to :account, default: -> { board.account }
   belongs_to :board, touch: true
   belongs_to :creator, class_name: "User", default: -> { Current.user }
 
@@ -14,6 +14,7 @@ class Card < ApplicationRecord
 
   before_save :set_default_title, if: :published?
   after_update :handle_board_change, if: :saved_change_to_board_id?
+  before_create :assign_number
 
   scope :reverse_chronologically, -> { order created_at:     :desc, id: :desc }
   scope :chronologically,         -> { order created_at:     :asc,  id: :asc  }
@@ -81,4 +82,8 @@ class Card < ApplicationRecord
     def grant_access_to_assignees
       board.accesses.grant_to(assignees)
     end
+
+    def assign_number
+      self.number ||= account.increment!(:cards_count).cards_count
+    end
 end
diff --git a/app/views/cards/display/_public_preview.html.erb b/app/views/cards/display/_public_preview.html.erb
index d3b36e229..edf73d3de 100644
--- a/app/views/cards/display/_public_preview.html.erb
+++ b/app/views/cards/display/_public_preview.html.erb
@@ -4,7 +4,7 @@
       <div class="card__board flex align-start">
           <span class="card__id">
             <span class="for-screen-reader">Card number</span>
-            <%= card.id %>
+            <%= card.number %>
           </span>
         <span class="card__board-name">
             <span class="overflow-ellipsis"><%= card.board.name %></span>
diff --git a/app/views/cards/display/common/_board.html.erb b/app/views/cards/display/common/_board.html.erb
index 96c2e191d..3e91a0d78 100644
--- a/app/views/cards/display/common/_board.html.erb
+++ b/app/views/cards/display/common/_board.html.erb
@@ -1,7 +1,7 @@
 <label class="card__board">
   <span class="card__id">
     <span class="for-screen-reader">Card number</span>
-    <%= card.id %>
+    <%= card.number %>
   </span>
   <span class="card__board-name">
     <span class="overflow-ellipsis"><%= card.board.name %></span>
diff --git a/app/views/events/event/_layout.html.erb b/app/views/events/event/_layout.html.erb
index 08c406002..9a2cd4c69 100644
--- a/app/views/events/event/_layout.html.erb
+++ b/app/views/events/event/_layout.html.erb
@@ -11,7 +11,7 @@
     <h4 class="card__board flex-inline align-start">
       <span class="card__id">
         <span class="for-screen-reader">Card number</span>
-        <%= card.id %>
+        <%= card.number %>
       </span>
       <span class="card__board-name">
         <span class="overflow-ellipsis"><%= event.board.name %></span>
diff --git a/app/views/prompts/cards/_card.html.erb b/app/views/prompts/cards/_card.html.erb
index 176d7f8f4..2308bc0c7 100644
--- a/app/views/prompts/cards/_card.html.erb
+++ b/app/views/prompts/cards/_card.html.erb
@@ -1,8 +1,8 @@
 <lexxy-prompt-item>
   <template type="menu">
-    #<%= card.id %> <%= card.title %>
+    #<%= card.number %> <%= card.title %>
   </template>
   <template type="editor">
-    <%= link_to "##{card.id} #{card.title}", card_url(card) %>
+    <%= link_to "##{card.number} #{card.title}", card_url(card) %>
   </template>
 </lexxy-prompt-item>
diff --git a/db/migrate/20251111153019_add_number_to_cards.rb b/db/migrate/20251111153019_add_number_to_cards.rb
new file mode 100644
index 000000000..bc5d0ca17
--- /dev/null
+++ b/db/migrate/20251111153019_add_number_to_cards.rb
@@ -0,0 +1,7 @@
+class AddNumberToCards < ActiveRecord::Migration[8.2]
+  def change
+    add_column :cards, :number, :bigint, null: false
+    add_column :accounts, :cards_count, :bigint, default: 0, null: false
+    add_index :cards, [:account_id, :number], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index ada94a5a7..205a0c5ad 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.2].define(version: 2025_11_11_122540) do
+ActiveRecord::Schema[8.2].define(version: 2025_11_11_153019) do
   create_table "accesses", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.datetime "accessed_at"
     t.bigint "board_id", null: false
@@ -35,6 +35,7 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_11_122540) do
   end
 
   create_table "accounts", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
+    t.bigint "cards_count", default: 0, null: false
     t.datetime "created_at", null: false
     t.integer "external_account_id"
     t.string "name", null: false
@@ -170,9 +171,11 @@ ActiveRecord::Schema[8.2].define(version: 2025_11_11_122540) do
     t.integer "creator_id", null: false
     t.date "due_on"
     t.datetime "last_active_at", null: false
+    t.bigint "number", null: false
     t.string "status", default: "drafted", null: false
     t.string "title"
     t.datetime "updated_at", null: false
+    t.index ["account_id", "number"], name: "index_cards_on_account_id_and_number", unique: true
     t.index ["board_id"], name: "index_cards_on_board_id"
     t.index ["column_id"], name: "index_cards_on_column_id"
     t.index ["last_active_at", "status"], name: "index_cards_on_last_active_at_and_status"
diff --git a/script/import-sqlite-database.rb b/script/import-sqlite-database.rb
index 238c09bc8..8be7728e3 100755
--- a/script/import-sqlite-database.rb
+++ b/script/import-sqlite-database.rb
@@ -227,9 +227,10 @@ class Import
     def copy_cards
       step("Copying cards", "Copied %{count} cards in %{duration}") do
         mapping[:cards] ||= {}
+        account.update_columns(cards_count: import.cards.maximum(:id) || 0)
+
         next_id = (Card.maximum(:id) || 0) + 1
 
-        # Collect all associated records to batch insert
         activity_spikes_to_insert = []
         engagements_to_insert = []
         goldnesses_to_insert = []
@@ -250,6 +251,7 @@ class Import
 
             cards_to_insert << {
               id: new_id,
+              number: old_card.id,
               account_id: account.id,
               board_id: mapping[:boards][old_card.board_id],
               column_id: old_card.column_id ? mapping[:columns][old_card.column_id] : nil,
@@ -324,7 +326,6 @@ class Import
           Card.insert_all(cards_to_insert)
         end
 
-        # Batch insert all associated records
         Card::ActivitySpike.insert_all(activity_spikes_to_insert) if activity_spikes_to_insert.any?
         Card::Engagement.insert_all(engagements_to_insert) if engagements_to_insert.any?
         Card::Goldness.insert_all(goldnesses_to_insert) if goldnesses_to_insert.any?
@@ -332,7 +333,6 @@ class Import
         Assignment.insert_all(assignments_to_insert) if assignments_to_insert.any?
         Closure.insert_all(closures_to_insert) if closures_to_insert.any?
 
-        # Second pass: copy rich text and attachments
         import.cards.find_each do |old_card|
           new_card_id = mapping[:cards][old_card.id]
           new_card = Card.find(new_card_id)
diff --git a/test/fixtures/accounts.yml b/test/fixtures/accounts.yml
index e13abf5a2..fbe0333e1 100644
--- a/test/fixtures/accounts.yml
+++ b/test/fixtures/accounts.yml
@@ -1,7 +1,9 @@
 37s:
   name: 37signals
   external_account_id: <%= ActiveRecord::FixtureSet.identify("37signals") %>
+  cards_count: 5
 
 initech:
   name: Initech LLC
   external_account_id: <%= ActiveRecord::FixtureSet.identify("initech") %>
+  cards_count: 0
diff --git a/test/fixtures/cards.yml b/test/fixtures/cards.yml
index e255496c4..46a7cad6d 100644
--- a/test/fixtures/cards.yml
+++ b/test/fixtures/cards.yml
@@ -1,4 +1,5 @@
 logo:
+  number: 1
   board: writebook
   creator: david
   column: writebook_triage
@@ -10,6 +11,7 @@ logo:
   account: 37s
 
 layout:
+  number: 2
   board: writebook
   creator: david
   column: writebook_triage
@@ -20,6 +22,7 @@ layout:
   account: 37s
 
 text:
+  number: 3
   board: writebook
   creator: kevin
   column: writebook_in_progress
@@ -30,6 +33,7 @@ text:
   account: 37s
 
 shipping:
+  number: 4
   board: writebook
   creator: kevin
   column: writebook_triage
@@ -40,6 +44,7 @@ shipping:
   account: 37s
 
 buy_domain:
+  number: 5
   board: writebook
   creator: david
   title: Buy domain
diff --git a/test/models/card_test.rb b/test/models/card_test.rb
index 3e4d3f32c..0c55f35c1 100644
--- a/test/models/card_test.rb
+++ b/test/models/card_test.rb
@@ -5,6 +5,19 @@ class CardTest < ActiveSupport::TestCase
     Current.session = sessions(:david)
   end
 
+  test "create assigns a number to the card" do
+    user = users(:david)
+    board = boards(:writebook)
+    account = board.account
+    card = nil
+
+    assert_difference -> { account.reload.cards_count }, +1 do
+      card = Card.create!(title: "Test", board: board, creator: user)
+    end
+
+    assert_equal account.reload.cards_count, card.number
+  end
+
   test "capturing messages" do
     assert_difference -> { cards(:logo).comments.count }, +1 do
       cards(:logo).comments.create!(body: "Agreed.")