diff --git a/Sources/DiffableDataSourceSnapshot.swift b/Sources/DiffableDataSourceSnapshot.swift
index c57a575..8d0ead1 100644
--- a/Sources/DiffableDataSourceSnapshot.swift
+++ b/Sources/DiffableDataSourceSnapshot.swift
@@ -8,12 +8,16 @@ public struct DiffableDataSourceSnapshot<SectionIdentifierType: Hashable, ItemId
 
     /// The number of item identifiers in the snapshot.
     public var numberOfItems: Int {
-        return itemIdentifiers.count
+        var count = 0
+        for section in structure.sections {
+            count += numberOfItems(inSection: section.differenceIdentifier)
+        }
+        return count
     }
 
     /// The number of section identifiers in the snapshot.
     public var numberOfSections: Int {
-        return sectionIdentifiers.count
+        return structure.sections.count
     }
 
     /// All section identifiers in the snapshot.
@@ -33,7 +37,7 @@ public struct DiffableDataSourceSnapshot<SectionIdentifierType: Hashable, ItemId
     ///
     /// - Returns: The number of item identifiers in the specified section.
     public func numberOfItems(inSection identifier: SectionIdentifierType) -> Int {
-        return itemIdentifiers(inSection: identifier).count
+        return structure.numberOfItems(in: identifier)
     }
 
     /// Returns the item identifiers in the specified section.
diff --git a/Sources/Internal/SnapshotStructure.swift b/Sources/Internal/SnapshotStructure.swift
index 35bcc67..89e08d9 100644
--- a/Sources/Internal/SnapshotStructure.swift
+++ b/Sources/Internal/SnapshotStructure.swift
@@ -56,6 +56,14 @@ struct SnapshotStructure<SectionID: Hashable, ItemID: Hashable> {
             .map { $0.differenceIdentifier }
     }
 
+    func numberOfItems(in sectionID: SectionID, file: StaticString = #file, line: UInt = #line) -> Int {
+        guard let sectionIndex = sectionIndex(of: sectionID) else {
+            specifiedSectionIsNotFound(sectionID, file: file, line: line)
+        }
+
+        return sections[sectionIndex].elements.count
+    }
+
     func items(in sectionID: SectionID, file: StaticString = #file, line: UInt = #line) -> [ItemID] {
         guard let sectionIndex = sectionIndex(of: sectionID) else {
             specifiedSectionIsNotFound(sectionID, file: file, line: line)