diff --git a/Android.bp b/Android.bp
index 4ec17f2..1658533 100644
--- a/Android.bp
+++ b/Android.bp
@@ -332,6 +332,7 @@
         "PlatformProperties",
     ],
     shared_libs: [
+        "apex_aidl_interface-cpp",
         "libandroid_net",
         "libbase",
         "libbinder",
@@ -367,6 +368,7 @@
     srcs: [
         ":libupdate_engine_aidl",
         "common/system_state.cc",
+        "aosp/apex_handler_android.cc",
         "aosp/binder_service_android.cc",
         "aosp/binder_service_stable_android.cc",
         "aosp/daemon_android.cc",
@@ -740,6 +742,7 @@
     test_suites: ["device-tests"],
 
     srcs: [
+        "aosp/apex_handler_android_unittest.cc",
         "aosp/dynamic_partition_control_android_unittest.cc",
         "aosp/update_attempter_android_unittest.cc",
         "certificate_checker_unittest.cc",
diff --git a/aosp/apex_handler_android.cc b/aosp/apex_handler_android.cc
new file mode 100644
index 0000000..cdbc983
--- /dev/null
+++ b/aosp/apex_handler_android.cc
@@ -0,0 +1,98 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <utility>
+
+#include <base/files/file_util.h>
+
+#include "update_engine/aosp/apex_handler_android.h"
+#include "update_engine/common/utils.h"
+
+namespace chromeos_update_engine {
+
+// Don't change this path... apexd relies on it.
+constexpr const char* kApexReserveSpaceDir = "/data/apex/ota_reserved";
+
+uint64_t ApexHandlerAndroid::CalculateSize(
+    const std::vector<ApexInfo>& apex_infos) const {
+  return CalculateSize(apex_infos, GetApexService());
+}
+
+uint64_t ApexHandlerAndroid::CalculateSize(
+    const std::vector<ApexInfo>& apex_infos,
+    android::sp<android::apex::IApexService> apex_service) const {
+  // The safest option is to allocate space for every compressed APEX
+  uint64_t size_required_default = 0;
+
+  // We might not need to decompress every APEX. Communicate with apexd to get
+  // accurate requirement.
+  int64_t size_from_apexd;
+  android::apex::CompressedApexInfoList compressed_apex_info_list;
+
+  for (const auto& apex_info : apex_infos) {
+    if (!apex_info.is_compressed()) {
+      continue;
+    }
+
+    size_required_default += apex_info.decompressed_size();
+
+    android::apex::CompressedApexInfo compressed_apex_info;
+    compressed_apex_info.moduleName = apex_info.package_name();
+    compressed_apex_info.versionCode = apex_info.version();
+    compressed_apex_info.decompressedSize = apex_info.decompressed_size();
+    compressed_apex_info_list.apexInfos.emplace_back(
+        std::move(compressed_apex_info));
+  }
+  if (size_required_default == 0 || apex_service == nullptr) {
+    return size_required_default;
+  }
+
+  auto result = apex_service->calculateSizeForCompressedApex(
+      compressed_apex_info_list, &size_from_apexd);
+  if (!result.isOk()) {
+    return size_required_default;
+  }
+  return size_from_apexd;
+}
+
+bool ApexHandlerAndroid::AllocateSpace(const uint64_t size_required) const {
+  return AllocateSpace(size_required, kApexReserveSpaceDir);
+}
+
+bool ApexHandlerAndroid::AllocateSpace(const uint64_t size_required,
+                                       const std::string& dir_path) const {
+  if (size_required == 0) {
+    return true;
+  }
+  base::FilePath path{dir_path};
+  // The filename is not important, it just needs to be under
+  // kApexReserveSpaceDir. We call it "full.tmp" because the current space
+  // estimation is simply adding up all decompressed sizes.
+  path = path.Append("full.tmp");
+  return utils::ReserveStorageSpace(path.value().c_str(), size_required);
+}
+
+android::sp<android::apex::IApexService> ApexHandlerAndroid::GetApexService()
+    const {
+  auto binder = android::defaultServiceManager()->waitForService(
+      android::String16("apexservice"));
+  if (binder == nullptr) {
+    return nullptr;
+  }
+  return android::interface_cast<android::apex::IApexService>(binder);
+}
+
+}  // namespace chromeos_update_engine
diff --git a/aosp/apex_handler_android.h b/aosp/apex_handler_android.h
new file mode 100644
index 0000000..aac1cd9
--- /dev/null
+++ b/aosp/apex_handler_android.h
@@ -0,0 +1,48 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_ANDROID_H_
+#define SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_ANDROID_H_
+
+#include <string>
+#include <vector>
+
+#include <android/apex/IApexService.h>
+#include <binder/IServiceManager.h>
+
+#include "update_engine/aosp/apex_handler_interface.h"
+#include "update_engine/update_metadata.pb.h"
+
+namespace chromeos_update_engine {
+
+class ApexHandlerAndroid : virtual public ApexHandlerInterface {
+ public:
+  uint64_t CalculateSize(const std::vector<ApexInfo>& apex_infos) const;
+  bool AllocateSpace(const uint64_t size_required) const;
+
+ private:
+  friend class ApexHandlerAndroidTest;
+  android::sp<android::apex::IApexService> GetApexService() const;
+  uint64_t CalculateSize(
+      const std::vector<ApexInfo>& apex_infos,
+      android::sp<android::apex::IApexService> apex_service) const;
+  bool AllocateSpace(const uint64_t size_required,
+                     const std::string& dir_path) const;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_ANDROID_H_
diff --git a/aosp/apex_handler_android_unittest.cc b/aosp/apex_handler_android_unittest.cc
new file mode 100644
index 0000000..3a99f79
--- /dev/null
+++ b/aosp/apex_handler_android_unittest.cc
@@ -0,0 +1,109 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include <utility>
+#include <filesystem>
+
+#include "update_engine/aosp/apex_handler_android.h"
+
+#include <android-base/file.h>
+#include <android-base/strings.h>
+#include <gtest/gtest.h>
+
+using android::base::EndsWith;
+
+namespace chromeos_update_engine {
+
+namespace fs = std::filesystem;
+
+class ApexHandlerAndroidTest : public ::testing::Test {
+ protected:
+  ApexHandlerAndroidTest() = default;
+
+  android::sp<android::apex::IApexService> GetApexService() const {
+    return apex_handler_.GetApexService();
+  }
+
+  uint64_t CalculateSize(
+      const std::vector<ApexInfo>& apex_infos,
+      android::sp<android::apex::IApexService> apex_service) const {
+    return apex_handler_.CalculateSize(apex_infos, apex_service);
+  }
+
+  bool AllocateSpace(const uint64_t size_required,
+                     const std::string& dir_path) const {
+    return apex_handler_.AllocateSpace(size_required, dir_path);
+  }
+
+  ApexInfo CreateApexInfo(const std::string& package_name,
+                          int version,
+                          bool is_compressed,
+                          int decompressed_size) {
+    ApexInfo result;
+    result.set_package_name(package_name);
+    result.set_version(version);
+    result.set_is_compressed(is_compressed);
+    result.set_decompressed_size(decompressed_size);
+    return std::move(result);
+  }
+
+  ApexHandlerAndroid apex_handler_;
+};
+
+// TODO(b/172911822): Once apexd has more optimized response for CalculateSize,
+//  improve this test
+TEST_F(ApexHandlerAndroidTest, CalculateSize) {
+  std::vector<ApexInfo> apex_infos;
+  ApexInfo compressed_apex_1 = CreateApexInfo("sample1", 1, true, 10);
+  ApexInfo compressed_apex_2 = CreateApexInfo("sample2", 2, true, 20);
+  apex_infos.push_back(compressed_apex_1);
+  apex_infos.push_back(compressed_apex_2);
+  auto apex_service = GetApexService();
+  EXPECT_TRUE(apex_service != nullptr) << "Apexservice not found";
+  int required_size = CalculateSize(apex_infos, apex_service);
+  EXPECT_EQ(required_size, 30);
+}
+
+TEST_F(ApexHandlerAndroidTest, AllocateSpace) {
+  // Allocating 0 space should be a no op
+  TemporaryDir td;
+  EXPECT_TRUE(AllocateSpace(0, td.path));
+  EXPECT_TRUE(fs::is_empty(td.path));
+
+  // Allocating non-zero space should create a file with tmp suffix
+  EXPECT_TRUE(AllocateSpace(2 << 20, td.path));
+  EXPECT_FALSE(fs::is_empty(td.path));
+  int num_of_file = 0;
+  for (const auto& entry : fs::directory_iterator(td.path)) {
+    num_of_file++;
+    EXPECT_TRUE(EndsWith(entry.path().string(), ".tmp"));
+    EXPECT_EQ(fs::file_size(entry.path()), 2u << 20);
+  }
+  EXPECT_EQ(num_of_file, 1);
+
+  // AllocateSpace should be safe to call twice
+  EXPECT_TRUE(AllocateSpace(100, td.path));
+  EXPECT_FALSE(fs::is_empty(td.path));
+  num_of_file = 0;
+  for (const auto& entry : fs::directory_iterator(td.path)) {
+    num_of_file++;
+    EXPECT_TRUE(EndsWith(entry.path().string(), ".tmp"));
+    EXPECT_EQ(fs::file_size(entry.path()), 100u);
+  }
+  EXPECT_EQ(num_of_file, 1);
+}
+
+}  // namespace chromeos_update_engine
diff --git a/aosp/apex_handler_interface.h b/aosp/apex_handler_interface.h
new file mode 100644
index 0000000..c3399b6
--- /dev/null
+++ b/aosp/apex_handler_interface.h
@@ -0,0 +1,36 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#ifndef SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_INTERFACE_H_
+#define SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_INTERFACE_H_
+
+#include <vector>
+
+#include "update_engine/update_metadata.pb.h"
+
+namespace chromeos_update_engine {
+
+class ApexHandlerInterface {
+ public:
+  virtual ~ApexHandlerInterface() = default;
+  virtual uint64_t CalculateSize(
+      const std::vector<ApexInfo>& apex_infos) const = 0;
+  virtual bool AllocateSpace(const uint64_t size_required) const = 0;
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // SYSTEM_UPDATE_ENGINE_AOSP_APEX_HANDLER_INTERFACE_H_
diff --git a/aosp/daemon_state_android.cc b/aosp/daemon_state_android.cc
index 9bdd175..fc89d73 100644
--- a/aosp/daemon_state_android.cc
+++ b/aosp/daemon_state_android.cc
@@ -18,6 +18,7 @@
 
 #include <base/logging.h>
 
+#include "update_engine/aosp/apex_handler_android.h"
 #include "update_engine/aosp/update_attempter_android.h"
 #include "update_engine/common/boot_control.h"
 #include "update_engine/common/boot_control_stub.h"
@@ -64,8 +65,12 @@
   certificate_checker_->Init();
 
   // Initialize the UpdateAttempter before the UpdateManager.
-  update_attempter_.reset(new UpdateAttempterAndroid(
-      this, prefs_.get(), boot_control_.get(), hardware_.get()));
+  update_attempter_.reset(
+      new UpdateAttempterAndroid(this,
+                                 prefs_.get(),
+                                 boot_control_.get(),
+                                 hardware_.get(),
+                                 std::make_unique<ApexHandlerAndroid>()));
 
   return true;
 }
diff --git a/aosp/sideload_main.cc b/aosp/sideload_main.cc
index 3cbc0c7..bf015c9 100644
--- a/aosp/sideload_main.cc
+++ b/aosp/sideload_main.cc
@@ -154,8 +154,11 @@
     return false;
   }
 
-  UpdateAttempterAndroid update_attempter(
-      &sideload_daemon_state, &prefs, boot_control.get(), hardware.get());
+  UpdateAttempterAndroid update_attempter(&sideload_daemon_state,
+                                          &prefs,
+                                          boot_control.get(),
+                                          hardware.get(),
+                                          nullptr);
   update_attempter.Init();
 
   TEST_AND_RETURN_FALSE(update_attempter.ApplyPayload(
diff --git a/aosp/update_attempter_android.cc b/aosp/update_attempter_android.cc
index 5523a58..c685855 100644
--- a/aosp/update_attempter_android.cc
+++ b/aosp/update_attempter_android.cc
@@ -71,9 +71,6 @@
 
 namespace chromeos_update_engine {
 
-// Don't change this path... apexd relies on it.
-constexpr const char* kApexReserveSpaceDir = "/data/apex/ota_reserved";
-
 namespace {
 
 // Minimum threshold to broadcast an status update in progress and time.
@@ -136,11 +133,13 @@
     DaemonStateInterface* daemon_state,
     PrefsInterface* prefs,
     BootControlInterface* boot_control,
-    HardwareInterface* hardware)
+    HardwareInterface* hardware,
+    std::unique_ptr<ApexHandlerInterface> apex_handler)
     : daemon_state_(daemon_state),
       prefs_(prefs),
       boot_control_(boot_control),
       hardware_(hardware),
+      apex_handler_android_(std::move(apex_handler)),
       processor_(new ActionProcessor()),
       clock_(new Clock()) {
   metrics_reporter_ = metrics::CreateMetricsReporter(
@@ -967,28 +966,6 @@
   return GetCurrentSlot() == 0 ? 1 : 0;
 }
 
-static uint64_t allocateSpaceForApex(const DeltaArchiveManifest& manifest) {
-  // TODO(b/178696931) call apexd's binder once there is one.
-  uint64_t size_required = 0;
-  for (const auto& apex_info : manifest.apex_info()) {
-    if (apex_info.is_compressed()) {
-      size_required += apex_info.decompressed_size();
-    }
-  }
-  if (size_required == 0) {
-    return 0;
-  }
-  base::FilePath path{kApexReserveSpaceDir};
-  // The filename is not important, it just needs to be under
-  // kApexReserveSpaceDir. We call it "full.tmp" because the current space
-  // estimation is simply adding up all decompressed sizes.
-  path = path.Append("full.tmp");
-  if (!utils::ReserveStorageSpace(path.value().c_str(), size_required)) {
-    return size_required;
-  }
-  return 0;
-}
-
 uint64_t UpdateAttempterAndroid::AllocateSpaceForPayload(
     const std::string& metadata_filename,
     const vector<string>& key_value_pair_headers,
@@ -1002,6 +979,13 @@
     return 0;
   }
 
+  std::vector<ApexInfo> apex_infos(manifest.apex_info().begin(),
+                                   manifest.apex_info().end());
+  uint64_t apex_size_required = 0;
+  if (apex_handler_android_ != nullptr) {
+    apex_size_required = apex_handler_android_->CalculateSize(apex_infos);
+  }
+
   string payload_id = GetPayloadId(headers);
   uint64_t required_size = 0;
   if (!DeltaPerformer::PreparePartitionsForUpdate(prefs_,
@@ -1015,14 +999,17 @@
       return 0;
     } else {
       LOG(ERROR) << "Insufficient space for payload: " << required_size
+                 << " bytes, apex decompression: " << apex_size_required
                  << " bytes";
-      return required_size;
+      return required_size + apex_size_required;
     }
   }
-  const auto apex_size = allocateSpaceForApex(manifest);
-  if (apex_size != 0) {
-    LOG(ERROR) << "Insufficient space for apex decompression: " << apex_size;
-    return required_size + apex_size;
+
+  if (apex_size_required > 0 && apex_handler_android_ != nullptr &&
+      !apex_handler_android_->AllocateSpace(apex_size_required)) {
+    LOG(ERROR) << "Insufficient space for apex decompression: "
+               << apex_size_required << " bytes";
+    return apex_size_required;
   }
 
   LOG(INFO) << "Successfully allocated space for payload.";
diff --git a/aosp/update_attempter_android.h b/aosp/update_attempter_android.h
index 499f8f6..70938bc 100644
--- a/aosp/update_attempter_android.h
+++ b/aosp/update_attempter_android.h
@@ -26,6 +26,7 @@
 #include <android-base/unique_fd.h>
 #include <base/time/time.h>
 
+#include "update_engine/aosp/apex_handler_interface.h"
 #include "update_engine/aosp/service_delegate_android_interface.h"
 #include "update_engine/client_library/include/update_engine/update_status.h"
 #include "update_engine/common/action_processor.h"
@@ -57,7 +58,8 @@
   UpdateAttempterAndroid(DaemonStateInterface* daemon_state,
                          PrefsInterface* prefs,
                          BootControlInterface* boot_control_,
-                         HardwareInterface* hardware_);
+                         HardwareInterface* hardware_,
+                         std::unique_ptr<ApexHandlerInterface> apex_handler);
   ~UpdateAttempterAndroid() override;
 
   // Further initialization to be done post construction.
@@ -205,6 +207,8 @@
   BootControlInterface* boot_control_;
   HardwareInterface* hardware_;
 
+  std::unique_ptr<ApexHandlerInterface> apex_handler_android_;
+
   // Last status notification timestamp used for throttling. Use monotonic
   // TimeTicks to ensure that notifications are sent even if the system clock is
   // set back in the middle of an update.
diff --git a/aosp/update_attempter_android_unittest.cc b/aosp/update_attempter_android_unittest.cc
index 173e943..f799df3 100644
--- a/aosp/update_attempter_android_unittest.cc
+++ b/aosp/update_attempter_android_unittest.cc
@@ -69,7 +69,7 @@
   FakeHardware hardware_;
 
   UpdateAttempterAndroid update_attempter_android_{
-      &daemon_state_, &prefs_, &boot_control_, &hardware_};
+      &daemon_state_, &prefs_, &boot_control_, &hardware_, nullptr};
 
   FakeClock* clock_;
   testing::NiceMock<MockMetricsReporter>* metrics_reporter_;