diff --git a/.changelog/bugfix-checksum-user-agent-features.json b/.changelog/bugfix-checksum-user-agent-features.json
new file mode 100644
index 000000000000..2bb74f481dda
--- /dev/null
+++ b/.changelog/bugfix-checksum-user-agent-features.json
@@ -0,0 +1,6 @@
+{
+  "type": "bugfix",
+  "category": "aws-cpp-sdk-core",
+  "contributor": "jonathan343",
+  "description": "Fix the flexible checksum business metrics reported in the User-Agent. CRC32 was reported as CRC32C, CRC64NVME was never reported, and the SHA512, XXHASH3, XXHASH64 and XXHASH128 metric IDs were wrong."
+}
diff --git a/src/aws-cpp-sdk-core/include/smithy/client/features/ChecksumInterceptor.h b/src/aws-cpp-sdk-core/include/smithy/client/features/ChecksumInterceptor.h
index 85a0e835a44f..4f361e0f4ca9 100644
--- a/src/aws-cpp-sdk-core/include/smithy/client/features/ChecksumInterceptor.h
+++ b/src/aws-cpp-sdk-core/include/smithy/client/features/ChecksumInterceptor.h
@@ -151,10 +151,10 @@ class ChecksumInterceptor : public smithy::interceptor::Interceptor {
  private:
   void addChecksumFeatureForChecksumName(const Aws::String& checksumName, const Aws::AmazonWebServiceRequest& request) {
     if (checksumName == "crc32") {
-      request.AddUserAgentFeature(Aws::Client::UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_CRC32C);
+      request.AddUserAgentFeature(Aws::Client::UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_CRC32);
     } else if (checksumName == "crc32c") {
       request.AddUserAgentFeature(Aws::Client::UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_CRC32C);
-    } else if (checksumName == "crc64") {
+    } else if (checksumName == "crc64nvme") {
       request.AddUserAgentFeature(Aws::Client::UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_CRC64);
     } else if (checksumName == "sha1") {
       request.AddUserAgentFeature(Aws::Client::UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_SHA1);
diff --git a/src/aws-cpp-sdk-core/source/client/UserAgent.cpp b/src/aws-cpp-sdk-core/source/client/UserAgent.cpp
index 098688119cb2..07559bfaee59 100644
--- a/src/aws-cpp-sdk-core/source/client/UserAgent.cpp
+++ b/src/aws-cpp-sdk-core/source/client/UserAgent.cpp
@@ -55,10 +55,10 @@ const std::pair<UserAgentFeature, const char*> BUSINESS_METRIC_MAPPING[] = {
     {UserAgentFeature::CREDENTIALS_LOGIN, "AD"},
     {UserAgentFeature::PROTOCOL_RPC_V2_CBOR, "M"},
     {UserAgentFeature::BEARER_SERVICE_ENV_VARS, "3"},
-    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_SHA512, "AE"},
-    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH64, "AG"},
-    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH3, "AF"},
-    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH128, "AH"},
+    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_SHA512, "AF"},
+    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH64, "AH"},
+    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH3, "AG"},
+    {UserAgentFeature::FLEXIBLE_CHECKSUMS_REQ_XXHASH128, "AI"},
     {UserAgentFeature::PAGINATOR, "C"},
     {UserAgentFeature::WAITER, "B"},
 };
diff --git a/tests/aws-cpp-sdk-s3-unit-tests/S3UnitTests.cpp b/tests/aws-cpp-sdk-s3-unit-tests/S3UnitTests.cpp
index 69c3ab632c67..da803b73c8c5 100644
--- a/tests/aws-cpp-sdk-s3-unit-tests/S3UnitTests.cpp
+++ b/tests/aws-cpp-sdk-s3-unit-tests/S3UnitTests.cpp
@@ -20,8 +20,10 @@
 #include <aws/testing/AwsTestHelpers.h>
 #include <aws/testing/MemoryTesting.h>
 #include <aws/testing/mocks/http/MockHttpClient.h>
+#include <aws/testing/utils/UserAgentUtils.h>
 #include <gtest/gtest.h>
 
+#include <functional>
 #include <memory>
 
 using namespace Aws;
@@ -441,6 +443,71 @@ TEST_F(S3UnitTest, PutObjectShouldHaveCorrectUserAgent) {
   EXPECT_TRUE(archMetadata < businessMetrics);
 }
 
+namespace {
+struct ChecksumFeatureTestCase {
+  ChecksumAlgorithm algorithm;
+  std::function<void(PutObjectRequest&)> setChecksum;
+  Aws::String metric;
+};
+}  // namespace
+
+TEST_F(S3UnitTest, PutObjectShouldTrackChecksumAlgorithmFeature) {
+  // FLEXIBLE_CHECKSUMS_REQ_* metric values, from the AWS SDK business metrics registry.
+  const Aws::Vector<ChecksumFeatureTestCase> testCases{
+    {ChecksumAlgorithm::CRC32, [](PutObjectRequest& r) { r.SetChecksumCRC32("Y2hlY2tzdW0="); }, "U"},
+    {ChecksumAlgorithm::CRC32C, [](PutObjectRequest& r) { r.SetChecksumCRC32C("Y2hlY2tzdW0="); }, "V"},
+    {ChecksumAlgorithm::CRC64NVME, [](PutObjectRequest& r) { r.SetChecksumCRC64NVME("Y2hlY2tzdW0="); }, "W"},
+    {ChecksumAlgorithm::SHA1, [](PutObjectRequest& r) { r.SetChecksumSHA1("Y2hlY2tzdW0="); }, "X"},
+    {ChecksumAlgorithm::SHA256, [](PutObjectRequest& r) { r.SetChecksumSHA256("Y2hlY2tzdW0="); }, "Y"},
+    {ChecksumAlgorithm::SHA512, [](PutObjectRequest& r) { r.SetChecksumSHA512("Y2hlY2tzdW0="); }, "AF"},
+    {ChecksumAlgorithm::XXHASH3, [](PutObjectRequest& r) { r.SetChecksumXXHASH3("Y2hlY2tzdW0="); }, "AG"},
+    {ChecksumAlgorithm::XXHASH64, [](PutObjectRequest& r) { r.SetChecksumXXHASH64("Y2hlY2tzdW0="); }, "AH"},
+    {ChecksumAlgorithm::XXHASH128, [](PutObjectRequest& r) { r.SetChecksumXXHASH128("Y2hlY2tzdW0="); }, "AI"},
+  };
+  Aws::Vector<Aws::String> allMetrics;
+  for (const auto& testCase : testCases) {
+    allMetrics.push_back(testCase.metric);
+  }
+
+  for (const auto& testCase : testCases) {
+    // The SDK either calculates the checksum, or sends the one set on the request.
+    for (const bool provided : {false, true}) {
+      SCOPED_TRACE(Aws::String(ChecksumAlgorithmMapper::GetNameForChecksumAlgorithm(testCase.algorithm)) +
+                   (provided ? " provided" : " calculated"));
+      // The mock client is shared by the suite, so start each case clean.
+      _mockHttpClient->Reset();
+      auto request = PutObjectRequest()
+        .WithBucket("big-boss")
+        .WithKey("snake-eater")
+        .WithChecksumAlgorithm(testCase.algorithm);
+      if (provided) {
+        testCase.setChecksum(request);
+      }
+      std::shared_ptr<IOStream> body = Aws::MakeShared<StringStream>(ALLOCATION_TAG, "phantom pain");
+      request.SetBody(body);
+
+      auto mockRequest = Aws::MakeShared<Standard::StandardHttpRequest>(ALLOCATION_TAG, "outer.heaven/mother-base", HttpMethod::HTTP_PUT);
+      mockRequest->SetResponseStreamFactory([]() -> IOStream* {
+        return Aws::New<StringStream>(ALLOCATION_TAG, "", std::ios_base::in | std::ios_base::binary);
+      });
+      auto mockResponse = Aws::MakeShared<Standard::StandardHttpResponse>(ALLOCATION_TAG, mockRequest);
+      mockResponse->SetResponseCode(HttpResponseCode::OK);
+      _mockHttpClient->AddResponseToReturn(mockResponse);
+
+      const auto response = _s3Client->PutObject(request);
+      EXPECT_TRUE(response.IsSuccess());
+      ASSERT_EQ(1u, _mockHttpClient->GetAllRequestsMade().size());
+
+      // Exactly one checksum algorithm metric is reported, and it's the right one.
+      const auto metrics = GetFeaturesForRequest(_mockHttpClient->GetMostRecentHttpRequest());
+      for (const auto& metric : allMetrics) {
+        const bool reported = std::find(metrics.begin(), metrics.end(), metric) != metrics.end();
+        EXPECT_EQ(metric == testCase.metric, reported) << "metric " << metric;
+      }
+    }
+  }
+}
+
 TEST_F(S3UnitTest, PutObjectShouldOverrideUserAgent) {
   auto request = PutObjectRequest()
     .WithBucket("ocelot")