diff --git a/esphome/components/api/api_frame_helper_noise.cpp b/esphome/components/api/api_frame_helper_noise.cpp
index e5ed1d86578..62073bb4401 100644
--- a/esphome/components/api/api_frame_helper_noise.cpp
+++ b/esphome/components/api/api_frame_helper_noise.cpp
@@ -497,8 +497,7 @@ APIError APINoiseFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuff
   if (frame_footer_size_)
     buffer.get_buffer()->resize(buffer.get_buffer()->size() + frame_footer_size_);
 
-  MessageInfo msg{type, 0,
-                  static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_ - frame_footer_size_)};
+  MessageInfo msg{type, 0, static_cast<uint16_t>(buffer.get_buffer()->size() - HEADER_PADDING - frame_footer_size_)};
   uint8_t *buf_start = buffer.get_buffer()->data();
   struct iovec iov;
   APIError aerr = this->encrypt_noise_message_(buf_start, msg, iov);
diff --git a/esphome/components/api/api_frame_helper_noise.h b/esphome/components/api/api_frame_helper_noise.h
index e56006d955a..53c18431d61 100644
--- a/esphome/components/api/api_frame_helper_noise.h
+++ b/esphome/components/api/api_frame_helper_noise.h
@@ -9,14 +9,16 @@ namespace esphome::api {
 
 class APINoiseFrameHelper final : public APIFrameHelper {
  public:
+  // Noise header structure:
+  // Pos 0: indicator (0x01)
+  // Pos 1-2: encrypted payload size (16-bit big-endian)
+  // Pos 3-6: encrypted type (16-bit) + data_len (16-bit)
+  // Pos 7+: actual payload data
+  static constexpr uint8_t HEADER_PADDING = 1 + 2 + 2 + 2;  // indicator + size + type + data_len
+
   APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, APINoiseContext &ctx)
       : APIFrameHelper(std::move(socket)), ctx_(ctx) {
-    // Noise header structure:
-    // Pos 0: indicator (0x01)
-    // Pos 1-2: encrypted payload size (16-bit big-endian)
-    // Pos 3-6: encrypted type (16-bit) + data_len (16-bit)
-    // Pos 7+: actual payload data
-    frame_header_padding_ = 7;
+    frame_header_padding_ = HEADER_PADDING;
   }
   ~APINoiseFrameHelper() override;
   APIError init() override;
diff --git a/esphome/components/api/api_frame_helper_plaintext.cpp b/esphome/components/api/api_frame_helper_plaintext.cpp
index 53ee58590de..b74b215e153 100644
--- a/esphome/components/api/api_frame_helper_plaintext.cpp
+++ b/esphome/components/api/api_frame_helper_plaintext.cpp
@@ -287,10 +287,10 @@ APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWrite
   assert(this->state_ == State::DATA);
 #endif
 
-  MessageInfo msg{type, 0, static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_)};
+  MessageInfo msg{type, 0, static_cast<uint16_t>(buffer.get_buffer()->size() - HEADER_PADDING)};
   uint8_t *buffer_data = buffer.get_buffer()->data();
-  uint8_t header_len = write_plaintext_header(buffer_data, msg, frame_header_padding_);
-  uint8_t *msg_start = buffer_data + frame_header_padding_ - header_len;
+  uint8_t header_len = write_plaintext_header(buffer_data, msg, HEADER_PADDING);
+  uint8_t *msg_start = buffer_data + HEADER_PADDING - header_len;
   uint16_t msg_len = static_cast<uint16_t>(header_len + msg.payload_size);
   LOG_PACKET_SENDING(msg_start, msg_len);
   return this->write_raw_fast_buf_(msg_start, msg_len);
@@ -302,15 +302,13 @@ APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffe
   assert(this->state_ == State::DATA);
   assert(!messages.empty());
 #endif
-
   uint8_t *buffer_data = buffer.get_buffer()->data();
   StaticVector<struct iovec, MAX_MESSAGES_PER_BATCH> iovs;
   uint16_t total_write_len = 0;
-  const uint8_t padding = frame_header_padding_;
 
   for (const auto &msg : messages) {
-    uint8_t header_len = write_plaintext_header(buffer_data + msg.offset, msg, padding);
-    uint8_t *msg_start = buffer_data + msg.offset + padding - header_len;
+    uint8_t header_len = write_plaintext_header(buffer_data + msg.offset, msg, HEADER_PADDING);
+    uint8_t *msg_start = buffer_data + msg.offset + HEADER_PADDING - header_len;
     size_t msg_len = static_cast<size_t>(header_len + msg.payload_size);
     iovs.push_back({msg_start, msg_len});
     total_write_len += msg_len;
diff --git a/esphome/components/api/api_frame_helper_plaintext.h b/esphome/components/api/api_frame_helper_plaintext.h
index 96d47e9c7bf..8314754715f 100644
--- a/esphome/components/api/api_frame_helper_plaintext.h
+++ b/esphome/components/api/api_frame_helper_plaintext.h
@@ -7,13 +7,15 @@ namespace esphome::api {
 
 class APIPlaintextFrameHelper final : public APIFrameHelper {
  public:
+  // Plaintext header structure (worst case):
+  // Pos 0: indicator (0x00)
+  // Pos 1-3: payload size varint (up to 3 bytes)
+  // Pos 4-5: message type varint (up to 2 bytes)
+  // Pos 6+: actual payload data
+  static constexpr uint8_t HEADER_PADDING = 1 + 3 + 2;  // indicator + size varint + type varint
+
   explicit APIPlaintextFrameHelper(std::unique_ptr<socket::Socket> socket) : APIFrameHelper(std::move(socket)) {
-    // Plaintext header structure (worst case):
-    // Pos 0: indicator (0x00)
-    // Pos 1-3: payload size varint (up to 3 bytes)
-    // Pos 4-5: message type varint (up to 2 bytes)
-    // Pos 6+: actual payload data
-    frame_header_padding_ = 6;
+    frame_header_padding_ = HEADER_PADDING;
   }
   ~APIPlaintextFrameHelper() override = default;
   APIError init() override;