diff --git a/ViewModels/Sources/ViewModels/CompositionViewModel.swift b/ViewModels/Sources/ViewModels/CompositionViewModel.swift
index 4345fcb..66115f8 100644
--- a/ViewModels/Sources/ViewModels/CompositionViewModel.swift
+++ b/ViewModels/Sources/ViewModels/CompositionViewModel.swift
@@ -16,6 +16,7 @@ public final class CompositionViewModel: ObservableObject, Identifiable {
     @Published public private(set) var isPostable = false
     @Published public private(set) var canAddAttachment = true
     @Published public private(set) var canAddNonImageAttachment = true
+    @Published public private(set) var remainingCharacters = CompositionViewModel.maxCharacters
 
     private var attachmentUploadCancellable: AnyCancellable?
 
@@ -32,10 +33,20 @@ public final class CompositionViewModel: ObservableObject, Identifiable {
             .map { $0.count < Self.maxAttachmentCount && $1 == nil }
             .assign(to: &$canAddAttachment)
         $attachmentViewModels.map(\.isEmpty).assign(to: &$canAddNonImageAttachment)
+        $text.map {
+            let tokens = $0.components(separatedBy: " ")
+
+            return tokens.map(\.countShorteningIfURL).reduce(tokens.count - 1, +)
+        }
+        .combineLatest($displayContentWarning, $contentWarning)
+        .map { Self.maxCharacters - ($0 + ($1 ? $2.count : 0)) }
+        .assign(to: &$remainingCharacters)
     }
 }
 
 public extension CompositionViewModel {
+    static let maxCharacters = 500
+
     typealias Id = UUID
 
     enum Event {
@@ -93,3 +104,9 @@ extension CompositionViewModel {
 private extension CompositionViewModel {
     static let maxAttachmentCount = 4
 }
+
+private extension String {
+    static let urlCharacterCount = 23
+
+    var countShorteningIfURL: Int { starts(with: "http://") || starts(with: "https://") ? Self.urlCharacterCount : count }
+}
diff --git a/Views/CompositionInputAccessoryView.swift b/Views/CompositionInputAccessoryView.swift
index ed66a92..f39b21e 100644
--- a/Views/CompositionInputAccessoryView.swift
+++ b/Views/CompositionInputAccessoryView.swift
@@ -109,6 +109,12 @@ private extension CompositionInputAccessoryView {
 
         stackView.addArrangedSubview(UIView())
 
+        let charactersLabel = UILabel()
+
+        stackView.addArrangedSubview(charactersLabel)
+        charactersLabel.font = .preferredFont(forTextStyle: .callout)
+
+
         stackView.addArrangedSubview(addButton)
         addButton.setImage(
             UIImage(
@@ -121,12 +127,17 @@ private extension CompositionInputAccessoryView {
             self.parentViewModel.insert(after: self.viewModel)
         }, for: .touchUpInside)
 
-        viewModel.$canAddAttachment
-            .sink {
-                mediaButton.isEnabled = $0
-                cameraButton.isEnabled = $0
-            }
-            .store(in: &cancellables)
+        viewModel.$canAddAttachment.sink {
+            mediaButton.isEnabled = $0
+            cameraButton.isEnabled = $0
+        }
+        .store(in: &cancellables)
+
+        viewModel.$remainingCharacters.sink {
+            charactersLabel.text = String($0)
+            charactersLabel.textColor = $0 < 0 ? .systemRed : .label
+        }
+        .store(in: &cancellables)
 
         viewModel.$isPostable
             .sink { [weak self] in self?.addButton.isEnabled = $0 }