diff --git a/.web-docs/components/builder/upcloud/README.md b/.web-docs/components/builder/upcloud/README.md
index 9c6d071..7e23126 100644
--- a/.web-docs/components/builder/upcloud/README.md
+++ b/.web-docs/components/builder/upcloud/README.md
@@ -36,6 +36,8 @@ The upcloud builder is used to generate storage templates on UpCloud.
 
 - `token` (string) - The API token to use when interfacing with the UpCloud API. This is mutually exclusive with username and password.
 
+- `server_plan` (string) - Server plan to use for the builder server. Defaults to `1xCPU-2GB`.
+
 - `storage_name` (string) - The name of the storage that will be used to find the first matching storage in the list of existing templates.
   
   Note that `storage_uuid` parameter has higher priority. You should use either `storage_uuid` or `storage_name` for not strict matching (e.g "ubuntu server 24.04").
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3158daf..7476dd1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@ See updating [Changelog example here](https://keepachangelog.com/en/1.0.0/)
 
 ## [Unreleased]
 
+### Added
+
+- `server_plan` parameter to builder configuration for selecting server plan to use during build.
+
 ## [1.9.2] - 2025-10-16
 
 ### Changed
diff --git a/builder/upcloud/artifact.go b/builder/upcloud/artifact.go
index f94db7e..a7ed1d8 100644
--- a/builder/upcloud/artifact.go
+++ b/builder/upcloud/artifact.go
@@ -32,7 +32,7 @@ func (a *Artifact) Files() []string {
 }
 
 func (a *Artifact) Id() string { //nolint:revive // method is required by packer-plugin-sdk
-	result := []string{}
+	result := make([]string, 0, len(a.Templates))
 	for _, t := range a.Templates {
 		result = append(result, t.UUID)
 	}
diff --git a/builder/upcloud/artifact_test.go b/builder/upcloud/artifact_test.go
index 97bff0d..9de2569 100644
--- a/builder/upcloud/artifact_test.go
+++ b/builder/upcloud/artifact_test.go
@@ -24,7 +24,7 @@ func TestArtifact_Id(t *testing.T) {
 	uuid2 := "some-uuid-2"
 	expected := fmt.Sprintf("%s,%s", uuid1, uuid2)
 
-	templates := []*upcloud.Storage{}
+	templates := make([]*upcloud.Storage, 0, 2)
 	templates = append(templates, &upcloud.Storage{UUID: uuid1}, &upcloud.Storage{UUID: uuid2})
 
 	a := &Artifact{Templates: templates}
@@ -39,7 +39,7 @@ func TestArtifact_String(t *testing.T) {
 	t.Parallel()
 	expected := `Storage template created, UUID: some-uuid`
 
-	templates := []*upcloud.Storage{}
+	templates := make([]*upcloud.Storage, 0, 1)
 	templates = append(templates, &upcloud.Storage{UUID: "some-uuid"})
 
 	a := &Artifact{Templates: templates}
@@ -52,7 +52,7 @@ func TestArtifact_String(t *testing.T) {
 
 func TestArtifact_Metadata(t *testing.T) {
 	t.Parallel()
-	templates := []*upcloud.Storage{}
+	templates := make([]*upcloud.Storage, 0, 2)
 	templates = append(templates,
 		&upcloud.Storage{
 			UUID:  "some-uuid",
diff --git a/builder/upcloud/builder_acc_test.go b/builder/upcloud/builder_acc_test.go
index f316977..fa00cf2 100644
--- a/builder/upcloud/builder_acc_test.go
+++ b/builder/upcloud/builder_acc_test.go
@@ -38,8 +38,8 @@ var testBuilderStorageName string
 //go:embed test-fixtures/json/networking.json
 var testBuilderNetworking string
 
-//go:embed test-fixtures/json/basic_standard_tier.json
-var testBuilderBasicStandardTier string
+//go:embed test-fixtures/json/plan_and_tier.json
+var testBuilderPlanAndTier string
 
 func TestBuilderAcc_default(t *testing.T) {
 	t.Parallel()
@@ -78,12 +78,12 @@ func TestBuilderAcc_storageName(t *testing.T) {
 	acctest.TestPlugin(t, testCase)
 }
 
-func TestBuilderAcc_standardTier(t *testing.T) {
+func TestBuilderAcc_planAndTier(t *testing.T) {
 	t.Parallel()
 	testAccPreCheck(t)
 	testCase := &acctest.PluginTestCase{
 		Name:     t.Name(),
-		Template: testBuilderBasicStandardTier,
+		Template: testBuilderPlanAndTier,
 		Check:    checkTestResult(t),
 		Teardown: teardown(t, t.Name()),
 	}
@@ -107,6 +107,9 @@ func TestBuilderAcc_networking(t *testing.T) {
 //go:embed test-fixtures/hcl2/basic.pkr.hcl
 var testBuildBasicHcl string
 
+//go:embed test-fixtures/hcl2/plan_and_tier.pkr.hcl
+var testBuilderPlanAndTierHcl string
+
 //go:embed test-fixtures/hcl2/storage-uuid.pkr.hcl
 var testBuilderStorageUUIDHcl string
 
@@ -128,6 +131,18 @@ func TestBuilderAcc_default_hcl(t *testing.T) {
 	acctest.TestPlugin(t, testCase)
 }
 
+func TestBuilderAcc_planAndTier_hcl(t *testing.T) {
+	t.Parallel()
+	testAccPreCheck(t)
+	testCase := &acctest.PluginTestCase{
+		Name:     t.Name(),
+		Template: testBuilderPlanAndTierHcl,
+		Check:    checkTestResult(t),
+		Teardown: teardown(t, t.Name()),
+	}
+	acctest.TestPlugin(t, testCase)
+}
+
 func TestBuilderAcc_storageUuid_hcl(t *testing.T) {
 	t.Parallel()
 	testAccPreCheck(t)
@@ -152,7 +167,7 @@ func TestBuilderAcc_storageName_hcl(t *testing.T) {
 	acctest.TestPlugin(t, testCase)
 }
 
-func TestBuilderAcc_network_interfaces(t *testing.T) {
+func TestBuilderAcc_network_interfaces_hcl(t *testing.T) {
 	t.Parallel()
 	testAccPreCheck(t)
 	testCase := &acctest.PluginTestCase{
diff --git a/builder/upcloud/config.go b/builder/upcloud/config.go
index 11eb74d..9d25b7e 100644
--- a/builder/upcloud/config.go
+++ b/builder/upcloud/config.go
@@ -74,6 +74,9 @@ type Config struct {
 	// The zone in which the server and template should be created (e.g. nl-ams1).
 	Zone string `mapstructure:"zone" required:"true"`
 
+	// Server plan to use for the builder server. Defaults to `1xCPU-2GB`.
+	ServerPlan string `mapstructure:"server_plan"`
+
 	// The UUID of the storage you want to use as a template when creating the server.
 	//
 	// Optionally use `storage_name` parameter to find matching storage
diff --git a/builder/upcloud/config.hcl2spec.go b/builder/upcloud/config.hcl2spec.go
index 9473784..f27c57e 100644
--- a/builder/upcloud/config.hcl2spec.go
+++ b/builder/upcloud/config.hcl2spec.go
@@ -71,6 +71,7 @@ type FlatConfig struct {
 	Password                  *string                `mapstructure:"password" cty:"password" hcl:"password"`
 	Token                     *string                `mapstructure:"token" cty:"token" hcl:"token"`
 	Zone                      *string                `mapstructure:"zone" required:"true" cty:"zone" hcl:"zone"`
+	ServerPlan                *string                `mapstructure:"server_plan" cty:"server_plan" hcl:"server_plan"`
 	StorageUUID               *string                `mapstructure:"storage_uuid" required:"true" cty:"storage_uuid" hcl:"storage_uuid"`
 	StorageName               *string                `mapstructure:"storage_name" cty:"storage_name" hcl:"storage_name"`
 	TemplatePrefix            *string                `mapstructure:"template_prefix" cty:"template_prefix" hcl:"template_prefix"`
@@ -158,6 +159,7 @@ func (*FlatConfig) HCL2Spec() map[string]hcldec.Spec {
 		"password":                     &hcldec.AttrSpec{Name: "password", Type: cty.String, Required: false},
 		"token":                        &hcldec.AttrSpec{Name: "token", Type: cty.String, Required: false},
 		"zone":                         &hcldec.AttrSpec{Name: "zone", Type: cty.String, Required: false},
+		"server_plan":                  &hcldec.AttrSpec{Name: "server_plan", Type: cty.String, Required: false},
 		"storage_uuid":                 &hcldec.AttrSpec{Name: "storage_uuid", Type: cty.String, Required: false},
 		"storage_name":                 &hcldec.AttrSpec{Name: "storage_name", Type: cty.String, Required: false},
 		"template_prefix":              &hcldec.AttrSpec{Name: "template_prefix", Type: cty.String, Required: false},
diff --git a/builder/upcloud/step_create_server.go b/builder/upcloud/step_create_server.go
index b16c84b..dbb304c 100644
--- a/builder/upcloud/step_create_server.go
+++ b/builder/upcloud/step_create_server.go
@@ -93,6 +93,7 @@ func (s *StepCreateServer) createServer(ctx context.Context, ui packer.Ui, drv d
 	}
 
 	response, err := drv.CreateServer(ctx, &driver.ServerOpts{
+		ServerPlan:   s.Config.ServerPlan,
 		StorageUUID:  storage.UUID,
 		StorageSize:  s.Config.StorageSize,
 		Zone:         s.Config.Zone,
diff --git a/builder/upcloud/test-fixtures/hcl2/basic_standard_tier.hcl b/builder/upcloud/test-fixtures/hcl2/plan_and_tier.pkr.hcl
similarity index 87%
rename from builder/upcloud/test-fixtures/hcl2/basic_standard_tier.hcl
rename to builder/upcloud/test-fixtures/hcl2/plan_and_tier.pkr.hcl
index 1202ef4..9bb8bdc 100644
--- a/builder/upcloud/test-fixtures/hcl2/basic_standard_tier.hcl
+++ b/builder/upcloud/test-fixtures/hcl2/plan_and_tier.pkr.hcl
@@ -1,9 +1,10 @@
 source "upcloud" "standard-tier" {
+  server_plan  = "2xCPU-4GB"
   storage_uuid = "01000000-0000-4000-8000-000150020100" # Rocky Linux 9
-  zone         = "pl-waw1"
   storage_tier = "standard"
+  zone         = "pl-waw1"
 }
 
 build {
   sources = ["source.upcloud.standard-tier"]
-} 
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/builder/upcloud/test-fixtures/json/basic_standard_tier.json b/builder/upcloud/test-fixtures/json/plan_and_tier.json
similarity index 83%
rename from builder/upcloud/test-fixtures/json/basic_standard_tier.json
rename to builder/upcloud/test-fixtures/json/plan_and_tier.json
index 8088bb7..91fdcee 100644
--- a/builder/upcloud/test-fixtures/json/basic_standard_tier.json
+++ b/builder/upcloud/test-fixtures/json/plan_and_tier.json
@@ -2,6 +2,7 @@
     "builders": [{
         "type": "upcloud",
         "zone": "nl-ams1",
+        "server_plan": "2xCPU-4GB",
         "storage_uuid": "01000000-0000-4000-8000-000150020100",
         "storage_tier": "standard"
     }]
diff --git a/builder/upcloud/utils.go b/builder/upcloud/utils.go
index bb573d7..986b91c 100644
--- a/builder/upcloud/utils.go
+++ b/builder/upcloud/utils.go
@@ -63,9 +63,9 @@ func sshHostCallback(state multistep.StateBag) (string, error) {
 }
 
 func convertNetworkTypes(rawNetworking []NetworkInterface) []request.CreateServerInterface {
-	networking := []request.CreateServerInterface{}
+	networking := make([]request.CreateServerInterface, 0, len(rawNetworking))
 	for _, iface := range rawNetworking {
-		ips := []request.CreateServerIPAddress{}
+		ips := make([]request.CreateServerIPAddress, 0, len(iface.IPAddresses))
 		for _, ip := range iface.IPAddresses {
 			ips = append(ips, request.CreateServerIPAddress{Family: ip.Family, Address: ip.Address})
 		}
diff --git a/docs-partials/builder/upcloud/Config-not-required.mdx b/docs-partials/builder/upcloud/Config-not-required.mdx
index 0e6160b..8a577ad 100644
--- a/docs-partials/builder/upcloud/Config-not-required.mdx
+++ b/docs-partials/builder/upcloud/Config-not-required.mdx
@@ -6,6 +6,8 @@
 
 - `token` (string) - The API token to use when interfacing with the UpCloud API. This is mutually exclusive with username and password.
 
+- `server_plan` (string) - Server plan to use for the builder server. Defaults to `1xCPU-2GB`.
+
 - `storage_name` (string) - The name of the storage that will be used to find the first matching storage in the list of existing templates.
   
   Note that `storage_uuid` parameter has higher priority. You should use either `storage_uuid` or `storage_name` for not strict matching (e.g "ubuntu server 24.04").
diff --git a/internal/driver/driver.go b/internal/driver/driver.go
index 538f848..0c56366 100644
--- a/internal/driver/driver.go
+++ b/internal/driver/driver.go
@@ -82,6 +82,7 @@ type (
 	}
 
 	ServerOpts struct {
+		ServerPlan   string
 		StorageUUID  string
 		StorageSize  int
 		Zone         string
@@ -409,13 +410,17 @@ func (d *driver) GetServerStorage(ctx context.Context, serverUUID string) (*upcl
 func (d *driver) prepareCreateRequest(opts *ServerOpts) *request.CreateServerRequest {
 	title := fmt.Sprintf("packer-%s-%s", DefaultHostname, getNowString())
 	titleDisk := fmt.Sprintf("%s-disk1", DefaultHostname)
+	plan := opts.ServerPlan
+	if plan == "" {
+		plan = DefaultPlan
+	}
 
 	request := request.CreateServerRequest{
 		Title:            title,
 		Hostname:         DefaultHostname,
 		Zone:             opts.Zone,
 		PasswordDelivery: request.PasswordDeliveryNone,
-		Plan:             DefaultPlan,
+		Plan:             plan,
 		StorageDevices: []request.CreateServerStorageDevice{
 			{
 				Action:  request.CreateServerStorageDeviceActionClone,
diff --git a/post-processor/upcloud-import/config_test.go b/post-processor/upcloud-import/config_test.go
index 0fa54ac..cae48e5 100644
--- a/post-processor/upcloud-import/config_test.go
+++ b/post-processor/upcloud-import/config_test.go
@@ -60,8 +60,8 @@ func TestNewConfig_BothAuthMethods(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "test-api-token", c.Token)
-	assert.Equal(t, "", c.Username)
-	assert.Equal(t, "", c.Password)
+	assert.Empty(t, c.Username)
+	assert.Empty(t, c.Password)
 }
 
 func TestNewConfig_NoAuthMethods(t *testing.T) {