diff --git a/Library/Homebrew/livecheck/strategy.rb b/Library/Homebrew/livecheck/strategy.rb
index 56d0ecb168..92b75552fb 100644
--- a/Library/Homebrew/livecheck/strategy.rb
+++ b/Library/Homebrew/livecheck/strategy.rb
@@ -178,7 +178,7 @@ module Homebrew
         ).returns(T::Array[String])
       }
       def self.post_args(post_form: nil, post_json: nil)
-        if post_form.present?
+        args = if post_form.present?
           require "uri"
           ["--data", URI.encode_www_form(post_form)]
         elsif post_json.present?
@@ -187,6 +187,12 @@ module Homebrew
         else
           []
         end
+
+        if (content_length = args[1]&.length)
+          args << "--header" << "Content-Length: #{content_length}"
+        end
+
+        args
       end
 
       # Collects HTTP response headers, starting with the provided URL.
diff --git a/Library/Homebrew/test/livecheck/strategy_spec.rb b/Library/Homebrew/test/livecheck/strategy_spec.rb
index 4ef416c331..396fb5ccb0 100644
--- a/Library/Homebrew/test/livecheck/strategy_spec.rb
+++ b/Library/Homebrew/test/livecheck/strategy_spec.rb
@@ -144,16 +144,22 @@ RSpec.describe Homebrew::Livecheck::Strategy do
   end
 
   describe "::post_args" do
+    let(:form_string_content_length) { "Content-Length: #{form_string.length}" }
+    let(:json_string_content_length) { "Content-Length: #{json_string.length}" }
+
     it "returns an array including `--data` and an encoded form data string" do
-      expect(strategy.post_args(post_form: post_hash)).to eq(["--data", form_string])
+      expect(strategy.post_args(post_form: post_hash))
+        .to eq(["--data", form_string, "--header", form_string_content_length])
 
       # If both `post_form` and `post_json` are present, only `post_form` will
       # be used.
-      expect(strategy.post_args(post_form: post_hash, post_json: post_hash)).to eq(["--data", form_string])
+      expect(strategy.post_args(post_form: post_hash, post_json: post_hash))
+        .to eq(["--data", form_string, "--header", form_string_content_length])
     end
 
     it "returns an array including `--json` and a JSON string" do
-      expect(strategy.post_args(post_json: post_hash)).to eq(["--json", json_string])
+      expect(strategy.post_args(post_json: post_hash))
+        .to eq(["--json", json_string, "--header", json_string_content_length])
     end
 
     it "returns an empty array if `post_form` value is blank" do
diff --git a/Library/Homebrew/utils/curl.rb b/Library/Homebrew/utils/curl.rb
index fb51876e0e..0fda86f324 100644
--- a/Library/Homebrew/utils/curl.rb
+++ b/Library/Homebrew/utils/curl.rb
@@ -277,15 +277,20 @@ module Utils
       ).returns(T::Hash[Symbol, T.untyped])
     }
     def curl_headers(*args, wanted_headers: [], **options)
-      get_retry_args = ["--request", "GET"]
+      base_args = ["--fail", "--location", "--silent"]
+      get_retry_args = []
+      if (is_post_request = args.include?("POST"))
+        base_args << "--dump-header" << "-"
+      else
+        base_args << "--head"
+        get_retry_args << "--request" << "GET"
+      end
+
       # This is a workaround for https://github.com/Homebrew/brew/issues/18213
       get_retry_args << "--http1.1" if curl_version >= Version.new("8.7") && curl_version < Version.new("8.10")
 
       [[], get_retry_args].each do |request_args|
-        result = curl_output(
-          "--fail", "--location", "--silent", "--head", *request_args, *args,
-          **options
-        )
+        result = curl_output(*base_args, *request_args, *args, **options)
 
         # We still receive usable headers with certain non-successful exit
         # statuses, so we special case them below.
@@ -295,6 +300,7 @@ module Utils
           CURL_RECV_ERROR_EXIT_CODE,
         ].include?(result.exit_status)
           parsed_output = parse_curl_output(result.stdout)
+          return parsed_output if is_post_request
 
           if request_args.empty?
             # If we didn't get any wanted header yet, retry using `GET`.