diff --git a/cli/js/file_info.ts b/cli/js/file_info.ts
index e7ac646fbf..827239769c 100644
--- a/cli/js/file_info.ts
+++ b/cli/js/file_info.ts
@@ -3,7 +3,7 @@ import { StatResponse } from "./ops/fs/stat.ts";
 import { build } from "./build.ts";
 
 export interface FileInfo {
-  len: number;
+  size: number;
   modified: number | null;
   accessed: number | null;
   created: number | null;
@@ -26,7 +26,7 @@ export interface FileInfo {
 export class FileInfoImpl implements FileInfo {
   private readonly _isFile: boolean;
   private readonly _isSymlink: boolean;
-  len: number;
+  size: number;
   modified: number | null;
   accessed: number | null;
   created: number | null;
@@ -64,7 +64,7 @@ export class FileInfoImpl implements FileInfo {
 
     this._isFile = this._res.isFile;
     this._isSymlink = this._res.isSymlink;
-    this.len = this._res.len;
+    this.size = this._res.size;
     this.modified = modified ? modified : null;
     this.accessed = accessed ? accessed : null;
     this.created = created ? created : null;
diff --git a/cli/js/lib.deno.ns.d.ts b/cli/js/lib.deno.ns.d.ts
index 751e4452b3..daae8b09d7 100644
--- a/cli/js/lib.deno.ns.d.ts
+++ b/cli/js/lib.deno.ns.d.ts
@@ -661,7 +661,7 @@ declare namespace Deno {
     append?: boolean;
     /** Sets the option for truncating a previous file. If a file is
      * successfully opened with this option set it will truncate the file to `0`
-     * length if it already exists. The file must be opened with write access
+     * size if it already exists. The file must be opened with write access
      * for truncate to work. */
     truncate?: boolean;
     /** Sets the option to allow creating a new file, if one doesn't already
@@ -1058,16 +1058,12 @@ declare namespace Deno {
 
   // @url js/file_info.d.ts
 
-  /** UNSTABLE: 'len' maybe should be 'length' or 'size'.
-   *
-   * A FileInfo describes a file and is returned by `stat`, `lstat`,
+  /** A FileInfo describes a file and is returned by `stat`, `lstat`,
    * `statSync`, `lstatSync`. A list of FileInfo is returned by `readdir`,
    * `readdirSync`. */
   export interface FileInfo {
-    /** **UNSTABLE**: `.len` maybe should be `.length` or `.size`.
-     *
-     * The size of the file, in bytes. */
-    len: number;
+    /** The size of the file, in bytes. */
+    size: number;
     /** The last modification time of the file. This corresponds to the `mtime`
      * field from `stat` on Linux/Mac OS and `ftLastWriteTime` on Windows. This
      * may not be available on all platforms. */
diff --git a/cli/js/ops/fs/stat.ts b/cli/js/ops/fs/stat.ts
index 032cc97ee2..20ca3e6b16 100644
--- a/cli/js/ops/fs/stat.ts
+++ b/cli/js/ops/fs/stat.ts
@@ -5,7 +5,7 @@ import { FileInfo, FileInfoImpl } from "../../file_info.ts";
 export interface StatResponse {
   isFile: boolean;
   isSymlink: boolean;
-  len: number;
+  size: number;
   modified: number;
   accessed: number;
   created: number;
diff --git a/cli/js/tests/files_test.ts b/cli/js/tests/files_test.ts
index 49fecabe0d..29e2812d48 100644
--- a/cli/js/tests/files_test.ts
+++ b/cli/js/tests/files_test.ts
@@ -19,7 +19,7 @@ unitTest({ perms: { read: true } }, async function filesCopyToStdout(): Promise<
   const file = await Deno.open(filename);
   assert(file.rid > 2);
   const bytesWritten = await Deno.copy(Deno.stdout, file);
-  const fileSize = Deno.statSync(filename).len;
+  const fileSize = Deno.statSync(filename).size;
   assertEquals(bytesWritten, fileSize);
   console.log("bytes written", bytesWritten);
   file.close();
@@ -234,12 +234,12 @@ unitTest(
     const f = await Deno.create(filename);
     let fileInfo = Deno.statSync(filename);
     assert(fileInfo.isFile());
-    assert(fileInfo.len === 0);
+    assert(fileInfo.size === 0);
     const enc = new TextEncoder();
     const data = enc.encode("Hello");
     await f.write(data);
     fileInfo = Deno.statSync(filename);
-    assert(fileInfo.len === 5);
+    assert(fileInfo.size === 5);
     f.close();
 
     // TODO: test different modes
@@ -258,11 +258,11 @@ unitTest(
     // assert file was created
     let fileInfo = Deno.statSync(filename);
     assert(fileInfo.isFile());
-    assertEquals(fileInfo.len, 0);
+    assertEquals(fileInfo.size, 0);
     // write some data
     await file.write(data);
     fileInfo = Deno.statSync(filename);
-    assertEquals(fileInfo.len, 13);
+    assertEquals(fileInfo.size, 13);
     // assert we can't read from file
     let thrown = false;
     try {
@@ -277,7 +277,7 @@ unitTest(
     // assert that existing file is truncated on open
     file = await Deno.open(filename, "w");
     file.close();
-    const fileSize = Deno.statSync(filename).len;
+    const fileSize = Deno.statSync(filename).size;
     assertEquals(fileSize, 0);
     await Deno.remove(tempDir, { recursive: true });
   }
@@ -296,11 +296,11 @@ unitTest(
     // assert file was created
     let fileInfo = Deno.statSync(filename);
     assert(fileInfo.isFile());
-    assertEquals(fileInfo.len, 0);
+    assertEquals(fileInfo.size, 0);
     // write some data
     await file.write(data);
     fileInfo = Deno.statSync(filename);
-    assertEquals(fileInfo.len, 13);
+    assertEquals(fileInfo.size, 13);
 
     const buf = new Uint8Array(20);
     // seeking from beginning of a file
diff --git a/cli/ops/fs.rs b/cli/ops/fs.rs
index 01ce548bab..6c978d51cf 100644
--- a/cli/ops/fs.rs
+++ b/cli/ops/fs.rs
@@ -431,7 +431,7 @@ fn op_copy_file(
       return Err(OpError::not_found("File not found".to_string()));
     }
 
-    // returns length of from as u64 (we ignore)
+    // returns size of from as u64 (we ignore)
     fs::copy(&from, &to)?;
     Ok(json!({}))
   })
@@ -469,7 +469,7 @@ fn get_stat_json(
   let mut json_val = json!({
     "isFile": metadata.is_file(),
     "isSymlink": metadata.file_type().is_symlink(),
-    "len": metadata.len(),
+    "size": metadata.len(),
     // In seconds. Available on both Unix or Windows.
     "modified":to_seconds!(metadata.modified()),
     "accessed":to_seconds!(metadata.accessed()),
diff --git a/std/archive/tar.ts b/std/archive/tar.ts
index 33a9ae0974..2680bcff25 100644
--- a/std/archive/tar.ts
+++ b/std/archive/tar.ts
@@ -334,7 +334,7 @@ export class Tar {
       );
     }
 
-    const fileSize = info?.len ?? opts.contentSize;
+    const fileSize = info?.size ?? opts.contentSize;
     assert(fileSize != null, "fileSize must be set");
     const tarData: TarDataWithSource = {
       fileName,
diff --git a/std/http/file_server.ts b/std/http/file_server.ts
index 28eaef44d5..a259acb3c4 100755
--- a/std/http/file_server.ts
+++ b/std/http/file_server.ts
@@ -102,7 +102,7 @@ async function serveFile(
 ): Promise<Response> {
   const [file, fileInfo] = await Promise.all([open(filePath), stat(filePath)]);
   const headers = new Headers();
-  headers.set("content-length", fileInfo.len.toString());
+  headers.set("content-length", fileInfo.size.toString());
   headers.set("content-type", "text/plain; charset=utf-8");
 
   const res = {
@@ -135,7 +135,7 @@ async function serveDir(
     } catch (e) {}
     listEntry.push({
       mode: modeToString(fileInfo.isDirectory(), mode),
-      size: fileInfo.isFile() ? fileLenToString(fileInfo.len) : "",
+      size: fileInfo.isFile() ? fileLenToString(fileInfo.size) : "",
       name: fileInfo.name ?? "",
       url: fileUrl
     });
diff --git a/std/node/_fs/_fs_dirent_test.ts b/std/node/_fs/_fs_dirent_test.ts
index 6fe0f4020b..36091d3e13 100644
--- a/std/node/_fs/_fs_dirent_test.ts
+++ b/std/node/_fs/_fs_dirent_test.ts
@@ -3,7 +3,7 @@ import { assert, assertEquals, assertThrows } from "../../testing/asserts.ts";
 import Dirent from "./_fs_dirent.ts";
 
 class FileInfoMock implements Deno.FileInfo {
-  len = -1;
+  size = -1;
   modified = -1;
   accessed = -1;
   created = -1;