diff --git a/api/src/main/java/org/apache/iceberg/Snapshot.java b/api/src/main/java/org/apache/iceberg/Snapshot.java
index 097806639b24..9bbb57ed4824 100644
--- a/api/src/main/java/org/apache/iceberg/Snapshot.java
+++ b/api/src/main/java/org/apache/iceberg/Snapshot.java
@@ -185,12 +185,14 @@ default Long firstRowId() {
   }
 
   /**
-   * The total number of newly added rows in this snapshot. It should be the summation of {@link
-   * ManifestFile#ADDED_ROWS_COUNT} for every manifest added in this snapshot.
+   * The upper bound of number of rows with assigned row IDs in this snapshot. It can be used safely
+   * to increment the table's `next-row-id` during a commit. It can be more than the number of rows
+   * added in this snapshot and include some existing rows.
    *
    * <p>This field is optional but is required when the table version supports row lineage.
    *
-   * @return the total number of new rows in this snapshot or null if the value was not stored.
+   * @return the upper bound of number of rows with assigned row IDs in this snapshot or null if the
+   *     value was not stored.
    */
   default Long addedRows() {
     return null;
diff --git a/format/spec.md b/format/spec.md
index 029b4f3821ef..cc048dd56a21 100644
--- a/format/spec.md
+++ b/format/spec.md
@@ -754,9 +754,9 @@ A snapshot consists of the following fields:
 | _optional_ | _required_ | _required_ | **`summary`**                | A string map that summarizes the snapshot changes, including `operation` as a _required_ field (see below)                         |
 | _optional_ | _optional_ | _optional_ | **`schema-id`**              | ID of the table's current schema when the snapshot was created                                                                     |
 |            |            | _required_ | **`first-row-id`**           | The first `_row_id` assigned to the first row in the first data file in the first manifest, see [Row Lineage](#row-lineage)        |
+|            |            | _required_ | **`added-rows`**             | The upper bound of the number of rows with assigned row IDs, see [Row Lineage](#row-lineage) |
 |            |            | _optional_ | **`key-id`**                 | ID of the encryption key that encrypts the manifest list key metadata |
 
-
 The snapshot summary's `operation` field is used by some operations, like snapshot expiration, to skip processing certain snapshots. Possible `operation` values are:
 
 *   `append` -- Only data files were added and no files were removed.
@@ -782,6 +782,10 @@ A snapshot's `first-row-id` is assigned to the table's current `next-row-id` on
 
 The snapshot's `first-row-id` is the starting `first_row_id` assigned to manifests in the snapshot's manifest list.
 
+The snapshot's `added-rows` captures the upper bound of the number of rows with assigned row IDs.
+It can be used safely to increment the table's `next-row-id` during a commit.
+It can be more than the number of rows added in this snapshot and include some existing rows,
+see [Row Lineage Example](#row-lineage-example).
 
 ### Manifest Lists