diff --git a/.buildkite/ci.mjs b/.buildkite/ci.mjs
index fe10000e54..101b65995a 100755
--- a/.buildkite/ci.mjs
+++ b/.buildkite/ci.mjs
@@ -104,8 +104,8 @@ function getTargetLabel(target) {
  */
 // Azure VM sizes — single source of truth for both ci.mjs and azure.mjs
 const azureVmSize = {
-  "windows-aarch64": "Standard_D16ps_v6", // 16 vCPU, 64 GiB, Cobalt 100
-  "windows-x64": "Standard_D16ds_v6", // 16 vCPU, 64 GiB
+  "windows-aarch64": "Standard_D4ps_v6", // 4 vCPU, 16 GiB, Cobalt 100
+  "windows-x64": "Standard_D4ds_v6", // 4 vCPU, 16 GiB
 };
 
 function getAzureVmSize(os, arch) {
diff --git a/scripts/packer/windows-arm64.pkr.hcl b/scripts/packer/windows-arm64.pkr.hcl
index c3fa19dee2..7aedba057d 100644
--- a/scripts/packer/windows-arm64.pkr.hcl
+++ b/scripts/packer/windows-arm64.pkr.hcl
@@ -13,7 +13,7 @@ source "azure-arm" "windows-arm64" {
   image_version   = "latest"
 
   // Build VM — ARM64 Cobalt 100
-  vm_size         = "Standard_D16ps_v6"
+  vm_size         = "Standard_D4ps_v6"
 
   // Use existing resource group instead of creating a temp one
   build_resource_group_name = var.resource_group
diff --git a/scripts/packer/windows-x64.pkr.hcl b/scripts/packer/windows-x64.pkr.hcl
index 9579403064..0723184956 100644
--- a/scripts/packer/windows-x64.pkr.hcl
+++ b/scripts/packer/windows-x64.pkr.hcl
@@ -13,7 +13,7 @@ source "azure-arm" "windows-x64" {
   image_version   = "latest"
 
   // Build VM
-  vm_size         = "Standard_D16ds_v6"
+  vm_size         = "Standard_D4ds_v6"
 
   // Use existing resource group instead of creating a temp one
   build_resource_group_name = var.resource_group