diff --git a/native/native_rust_library/src/backup.rs b/native/native_rust_library/src/backup.rs
--- a/native/native_rust_library/src/backup.rs
+++ b/native/native_rust_library/src/backup.rs
@@ -258,6 +258,7 @@
         user_id,
         siwe_backup_msg,
         keyserver_device_id,
+        ..
       } = result;
 
       let siwe_backup_data = match siwe_backup_msg {
@@ -380,19 +381,9 @@
     Err(err) => return Err(err.into()),
   };
 
-  let LatestBackupInfoResponse {
-    backup_id,
-    user_id,
-    siwe_backup_msg,
-    keyserver_device_id,
-  } = serde_json::from_slice(&backup_info_response)?;
-
-  Ok(Some(LatestBackupInfoResponse {
-    backup_id,
-    user_id,
-    siwe_backup_msg,
-    keyserver_device_id,
-  }))
+  let response: LatestBackupInfoResponse =
+    serde_json::from_slice(&backup_info_response)?;
+  Ok(Some(response))
 }
 
 async fn download_backup_keys(
diff --git a/services/backup/src/database/mod.rs b/services/backup/src/database/mod.rs
--- a/services/backup/src/database/mod.rs
+++ b/services/backup/src/database/mod.rs
@@ -13,7 +13,7 @@
   types::{AttributeValue, DeleteRequest, ReturnValue, WriteRequest},
 };
 use comm_lib::{
-  blob::client::BlobServiceClient,
+  blob::{client::BlobServiceClient, types::BlobInfo},
   database::{
     self, batch_operations::ExponentialBackoffConfig, parse_int_attribute,
     AttributeMap, Error,
@@ -330,6 +330,33 @@
     Ok(items)
   }
 
+  pub async fn get_blob_infos_and_size_for_logs(
+    &self,
+    user_id: &str,
+    backup_id: &str,
+  ) -> Result<(Vec<BlobInfo>, u64), Error> {
+    let mut blob_infos = Vec::new();
+    let mut logs_ddb_size = 0u64;
+
+    let log_items = self
+      .fetch_all_log_items_for_backup(user_id, backup_id)
+      .await?;
+
+    use comm_lib::database::blob::BlobOrDBContent as LogContent;
+    for log in log_items {
+      match log.content {
+        LogContent::Blob(blob_info) => blob_infos.push(blob_info),
+        LogContent::Database(db_content) => {
+          logs_ddb_size += db_content.len() as u64;
+        }
+      }
+
+      blob_infos.extend(log.attachments);
+    }
+
+    Ok((blob_infos, logs_ddb_size))
+  }
+
   pub async fn remove_log_items_for_backup(
     &self,
     user_id: &str,
diff --git a/services/backup/src/http/handlers/backup.rs b/services/backup/src/http/handlers/backup.rs
--- a/services/backup/src/http/handlers/backup.rs
+++ b/services/backup/src/http/handlers/backup.rs
@@ -6,7 +6,10 @@
 use comm_lib::{
   auth::{AuthorizationCredential, UserIdentity},
   backup::LatestBackupInfoResponse,
-  blob::{client::BlobServiceClient, types::BlobInfo},
+  blob::{
+    client::BlobServiceClient,
+    types::{http::BlobSizesRequest, BlobInfo},
+  },
   http::{
     auth_service::Authenticated,
     multipart::{get_named_text_field, get_text_field},
@@ -430,6 +433,7 @@
   path: web::Path<String>,
   db_client: web::Data<DatabaseClient>,
   auth_service: comm_lib::auth::AuthService,
+  blob_client: Authenticated<BlobServiceClient>,
 ) -> actix_web::Result<impl Responder> {
   let user_identifier = path.into_inner();
   let user_id = find_user_id(&user_identifier).await?;
@@ -445,11 +449,22 @@
   let keyserver_device_id =
     find_keyserver_device_for_user(&user_id, &auth_service).await?;
 
+  let total_backup_size = get_total_backup_size(
+    &user_id,
+    &backup_item.backup_id,
+    &auth_service,
+    &db_client,
+    &blob_client,
+  )
+  .await?;
+
   let response = LatestBackupInfoResponse {
     backup_id: backup_item.backup_id,
     user_id,
     siwe_backup_msg: backup_item.siwe_backup_msg,
     keyserver_device_id,
+    total_backup_size,
+    creation_timestamp: backup_item.created.to_rfc3339(),
   };
 
   Ok(web::Json(response))
@@ -563,3 +578,41 @@
 
   Ok((item, revokes))
 }
+
+async fn get_total_backup_size(
+  user_id: &str,
+  backup_id: &str,
+  auth_service: &comm_lib::auth::AuthService,
+  db_client: &DatabaseClient,
+  blob_client: &BlobServiceClient,
+) -> Result<u64, BackupError> {
+  let backup_item = db_client
+    .find_backup_item(user_id, backup_id)
+    .await?
+    .ok_or(BackupError::NoBackup)?;
+
+  // gather blob infos for backup item
+  let mut blob_infos = backup_item.attachments;
+  blob_infos.push(backup_item.user_keys);
+  blob_infos.extend(backup_item.user_data);
+
+  // gather blob infos and DDB size for logs
+  let (log_blob_infos, ddb_logs_size) = db_client
+    .get_blob_infos_and_size_for_logs(user_id, &backup_item.backup_id)
+    .await?;
+  blob_infos.extend(log_blob_infos);
+
+  // we have to re-auth blob client with s2s token because the sizes endpoint is service-only
+  let credential = auth_service.get_services_token().await?;
+  let blob_client = blob_client.with_authentication(credential.into());
+
+  // query Blob Service for blobs size
+  let blob_hashes = blob_infos.into_iter().map(|it| it.blob_hash).collect();
+  let total_blobs_size = blob_client
+    .fetch_blob_sizes(BlobSizesRequest { blob_hashes })
+    .await?
+    .total_size();
+
+  let total_backup_size = total_blobs_size + ddb_logs_size;
+  Ok(total_backup_size)
+}
diff --git a/shared/comm-lib/src/backup/mod.rs b/shared/comm-lib/src/backup/mod.rs
--- a/shared/comm-lib/src/backup/mod.rs
+++ b/shared/comm-lib/src/backup/mod.rs
@@ -14,6 +14,9 @@
   pub siwe_backup_msg: Option<String>,
   #[serde(rename = "keyserverDeviceID")]
   pub keyserver_device_id: Option<String>,
+  // ISO 8601 / RFC 3339 DateTime string
+  pub creation_timestamp: String,
+  pub total_backup_size: u64,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]