diff --git a/CHANGELOG.md b/CHANGELOG.md
index b80e5863765..cd8ab7f83bb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,9 @@ release.
   ([#2617](https://github.com/open-telemetry/opentelemetry-specification/pull/2617))
 - Add `rpc.grpc.status_code` to RPC metric semantic conventions
   ([#2604](https://github.com/open-telemetry/opentelemetry-specification/pull/2604)).
+- Add `http.*.*.size` metric semantic conventions for tracking size of requests
+  / responses for http servers / clients
+  ([#2588](https://github.com/open-telemetry/opentelemetry-specification/pull/2588)).
 
 ### Compatibility
 
diff --git a/specification/metrics/semantic_conventions/http-metrics.md b/specification/metrics/semantic_conventions/http-metrics.md
index 1969274bf86..9919e3451b7 100644
--- a/specification/metrics/semantic_conventions/http-metrics.md
+++ b/specification/metrics/semantic_conventions/http-metrics.md
@@ -23,20 +23,24 @@ Below is a table of HTTP server metric instruments.
 
 | Name                          | Instrument Type ([*](README.md#instrument-types)) | Unit         | Unit ([UCUM](README.md#instrument-units)) | Description                                                                  |
 |-------------------------------|---------------------------------------------------|--------------|-------------------------------------------|------------------------------------------------------------------------------|
-| `http.server.duration`        | Histogram                                         | milliseconds | `ms`                                      | measures the duration of the inbound HTTP request                            |
+| `http.server.duration`        | Histogram                                         | milliseconds | `ms`                                      | measures the duration inbound HTTP requests                                  |
+| `http.server.request.size`    | Histogram                                         | bytes        | `By`                                      | measures the size of HTTP request messages (compressed)                      |
+| `http.server.response.size`   | Histogram                                         | bytes        | `By`                                      | measures the size of HTTP response messages (compressed)                     |
 | `http.server.active_requests` | UpDownCounter                                     | requests     | `{requests}`                              | measures the number of concurrent HTTP requests that are currently in-flight |
 
 ### HTTP Client
 
 Below is a table of HTTP client metric instruments.
 
-| Name                   | Instrument Type ([*](README.md#instrument-types)) | Unit         | Unit ([UCUM](README.md#instrument-units)) | Description                                        |
-|------------------------|---------------------------------------------------|--------------|-------------------------------------------|----------------------------------------------------|
-| `http.client.duration` | Histogram                                         | milliseconds | `ms`                                      | measures the duration of the outbound HTTP request |
+| Name                        | Instrument Type ([*](README.md#instrument-types)) | Unit         | Unit ([UCUM](README.md#instrument-units)) | Description                                              |
+|-----------------------------|---------------------------------------------------|--------------|-------------------------------------------|----------------------------------------------------------|
+| `http.client.duration`      | Histogram                                         | milliseconds | `ms`                                      | measures the duration outbound HTTP requests             |
+| `http.client.request.size`  | Histogram                                         | bytes        | `By`                                      | measures the size of HTTP request messages (compressed)  |
+| `http.client.response.size` | Histogram                                         | bytes        | `By`                                      | measures the size of HTTP response messages (compressed) |
 
 ## Attributes
 
-Below is a table of the attributes that SHOULD be included on `duration` metric events
+Below is a table of the attributes that SHOULD be included on `duration` and `size` metric events
 and whether they should be on server, client, or both types of HTTP metric events:
 
 | Name               | Type                | Requirement Level                                            | Notes and examples                                                                                                                                                                                                  |