diff --git a/.chloggen/http-request-response-size.yaml b/.chloggen/http-request-response-size.yaml
new file mode 100755
index 000000000..c823b94a9
--- /dev/null
+++ b/.chloggen/http-request-response-size.yaml
@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+#
+# If your change doesn't affect end users you should instead start
+# your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the area of concern in the attributes-registry, (e.g. http, cloud, db)
+component: http
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add `http.request.size` and `http.response.size` attributes for the total number of bytes in http messages
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+# The values here must be integers.
+issues: [38, 84]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
diff --git a/docs/attributes-registry/http.md b/docs/attributes-registry/http.md
index 9363bed22..31fb5b635 100644
--- a/docs/attributes-registry/http.md
+++ b/docs/attributes-registry/http.md
@@ -14,8 +14,10 @@
 | `http.request.method` | string | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>HTTP request method. [2] | `GET`; `POST`; `HEAD` |
 | `http.request.method_original` | string | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>Original HTTP method sent by the client in the request line. | `GeT`; `ACL`; `foo` |
 | `http.request.resend_count` | int | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>The ordinal number of request resending attempt (for any reason, including redirects). [3] | `3` |
+| `http.request.size` | int | The total size of the request in bytes. This should be the total number of bytes sent over the wire, including the request line (HTTP/1.1), framing (HTTP/2 and HTTP/3), headers, and request body if any. | `1437` |
 | `http.response.body.size` | int | The size of the response payload body in bytes. This is the number of bytes transferred excluding headers and is often, but not always, present as the [Content-Length](https://www.rfc-editor.org/rfc/rfc9110.html#field.content-length) header. For requests using transport encoding, this should be the compressed size. | `3495` |
 | `http.response.header.<key>` | string[] | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>HTTP response headers, `<key>` being the normalized HTTP Header name (lowercase), the value being the header values. [4] | `http.response.header.content-type=["application/json"]`; `http.response.header.my-custom-header=["abc", "def"]` |
+| `http.response.size` | int | The total size of the response in bytes. This should be the total number of bytes sent over the wire, including the status line (HTTP/1.1), framing (HTTP/2 and HTTP/3), headers, and response body and trailers if any. | `1437` |
 | `http.response.status_code` | int | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>[HTTP response status code](https://tools.ietf.org/html/rfc7231#section-6). | `200` |
 | `http.route` | string | ![Stable](https://img.shields.io/badge/-stable-lightgreen)<br>The matched route, that is, the path template in the format used by the respective server framework. [5] | `/users/:userID?`; `{controller}/{action}/{id?}` |
 
diff --git a/model/registry/http.yaml b/model/registry/http.yaml
index a4d4839eb..ee0ff9329 100644
--- a/model/registry/http.yaml
+++ b/model/registry/http.yaml
@@ -95,6 +95,13 @@ groups:
           was the cause of the resending (e.g. redirection, authorization failure, 503 Server Unavailable, network issues,
           or any other).
         examples: 3
+      - id: request.size
+        type: int
+        brief: >
+          The total size of the request in bytes. This should be the total number of bytes sent over the wire, including the request line (HTTP/1.1),
+          framing (HTTP/2 and HTTP/3), headers, and request body if any.
+        examples: 1437
+        stability: experimental
       - id: response.body.size
         type: int
         brief: >
@@ -118,6 +125,13 @@ groups:
           or a single-item array containing a possibly comma-concatenated string, depending on the way
           the HTTP library provides access to headers.
         examples: ['http.response.header.content-type=["application/json"]', 'http.response.header.my-custom-header=["abc", "def"]']
+      - id: response.size
+        type: int
+        brief: >
+          The total size of the response in bytes. This should be the total number of bytes sent over the wire, including the status line (HTTP/1.1),
+          framing (HTTP/2 and HTTP/3), headers, and response body and trailers if any.
+        examples: 1437
+        stability: experimental
       - id: response.status_code
         stability: stable
         type: int