diff --git a/src/libraries/System.Private.CoreLib/src/System/BitConverter.cs b/src/libraries/System.Private.CoreLib/src/System/BitConverter.cs
index d6666fb704aabf..6c874d8037b558 100644
--- a/src/libraries/System.Private.CoreLib/src/System/BitConverter.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/BitConverter.cs
@@ -623,7 +623,7 @@ public static uint ToUInt32(ReadOnlySpan<byte> value)
         }
 
         /// <summary>
-        /// Returns a 64-bit unsigned integer converted from four bytes at a specified position in a byte array.
+        /// Returns a 64-bit unsigned integer converted from eight bytes at a specified position in a byte array.
         /// </summary>
         /// <param name="value">An array of bytes.</param>
         /// <param name="startIndex">The starting position within <paramref name="value"/>.</param>
@@ -653,7 +653,7 @@ public static ulong ToUInt64(ReadOnlySpan<byte> value)
         }
 
         /// <summary>
-        /// Returns a 128-bit unsigned integer converted from four bytes at a specified position in a byte array.
+        /// Returns a 128-bit unsigned integer converted from sixteen bytes at a specified position in a byte array.
         /// </summary>
         /// <param name="value">An array of bytes.</param>
         /// <param name="startIndex">The starting position within <paramref name="value"/>.</param>
@@ -746,7 +746,7 @@ public static float ToSingle(ReadOnlySpan<byte> value)
         }
 
         /// <summary>
-        /// Returns a double-precision floating point number converted from four bytes at a specified position in a byte array.
+        /// Returns a double-precision floating point number converted from eight bytes at a specified position in a byte array.
         /// </summary>
         /// <param name="value">An array of bytes.</param>
         /// <param name="startIndex">The starting position within <paramref name="value"/>.</param>