diff --git a/cmd/metal-api/internal/metal/partition.go b/cmd/metal-api/internal/metal/partition.go
index a1b89378e..b748debbc 100644
--- a/cmd/metal-api/internal/metal/partition.go
+++ b/cmd/metal-api/internal/metal/partition.go
@@ -6,6 +6,7 @@ type Partition struct {
 	BootConfiguration          BootConfiguration `rethinkdb:"bootconfig" json:"bootconfig"`
 	MgmtServiceAddress         string            `rethinkdb:"mgmtserviceaddr" json:"mgmtserviceaddr"`
 	PrivateNetworkPrefixLength int               `rethinkdb:"privatenetworkprefixlength" json:"privatenetworkprefixlength"`
+	MachineReserve             MachineReserve    `rethinkdb:"machinereserve" json:"machinereserve"`
 }
 
 // BootConfiguration defines the metal-hammer initrd, kernel and commandline
@@ -15,6 +16,9 @@ type BootConfiguration struct {
 	CommandLine string `rethinkdb:"commandline" json:"commandline"`
 }
 
+// MachineReserve configures spare machine size to count
+type MachineReserve map[string]int
+
 // Partitions is a list of partitions.
 type Partitions []Partition
 
diff --git a/cmd/metal-api/internal/service/partition-service.go b/cmd/metal-api/internal/service/partition-service.go
index 43bad6fba..1c13be334 100644
--- a/cmd/metal-api/internal/service/partition-service.go
+++ b/cmd/metal-api/internal/service/partition-service.go
@@ -193,6 +193,12 @@ func (r partitionResource) createPartition(request *restful.Request, response *r
 	if requestPayload.PartitionBootConfiguration.CommandLine != nil {
 		commandLine = *requestPayload.PartitionBootConfiguration.CommandLine
 	}
+	mr := metal.MachineReserve{}
+	if requestPayload.MachineReserve != nil {
+		for k, v := range *requestPayload.MachineReserve {
+			mr[k] = v
+		}
+	}
 
 	p := &metal.Partition{
 		Base: metal.Base{
@@ -207,6 +213,7 @@ func (r partitionResource) createPartition(request *restful.Request, response *r
 			KernelURL:   kernelURL,
 			CommandLine: commandLine,
 		},
+		MachineReserve: mr,
 	}
 
 	fqn := metal.TopicMachine.GetFQN(p.GetID())
@@ -279,6 +286,13 @@ func (r partitionResource) updatePartition(request *restful.Request, response *r
 	if requestPayload.PartitionBootConfiguration.CommandLine != nil {
 		newPartition.BootConfiguration.CommandLine = *requestPayload.PartitionBootConfiguration.CommandLine
 	}
+	if requestPayload.MachineReserve != nil {
+		mr := metal.MachineReserve{}
+		for k, v := range *requestPayload.MachineReserve {
+			mr[k] = v
+		}
+		newPartition.MachineReserve = mr
+	}
 
 	err = r.ds.UpdatePartition(oldPartition, &newPartition)
 	if checkError(request, response, utils.CurrentFuncName(), err) {
@@ -361,6 +375,7 @@ func (r partitionResource) calcPartitionCapacity() ([]v1.PartitionCapacity, erro
 				cap.OtherMachines = append(cap.OtherMachines, m.ID)
 			}
 
+			cap.Reserved = p.MachineReserve[size]
 			cap.Total++
 		}
 		sc := []v1.ServerCapacity{}
diff --git a/cmd/metal-api/internal/service/v1/partition.go b/cmd/metal-api/internal/service/v1/partition.go
index b8e8e9abf..44afb8b6a 100644
--- a/cmd/metal-api/internal/service/v1/partition.go
+++ b/cmd/metal-api/internal/service/v1/partition.go
@@ -19,12 +19,14 @@ type PartitionCreateRequest struct {
 	Common
 	PartitionBase
 	PartitionBootConfiguration PartitionBootConfiguration `json:"bootconfig" description:"the boot configuration of this partition"`
+	MachineReserve             *MachineReserve            `json:"machine_reserve,omitempty"`
 }
 
 type PartitionUpdateRequest struct {
 	Common
 	MgmtServiceAddress         *string                     `json:"mgmtserviceaddress" description:"the address to the management service of this partition" optional:"true"`
 	PartitionBootConfiguration *PartitionBootConfiguration `json:"bootconfig" description:"the boot configuration of this partition" optional:"true"`
+	MachineReserve             *MachineReserve             `json:"machine_reserve,omitempty"`
 }
 
 type PartitionResponse struct {
@@ -32,6 +34,7 @@ type PartitionResponse struct {
 	PartitionBase
 	PartitionBootConfiguration PartitionBootConfiguration `json:"bootconfig" description:"the boot configuration of this partition"`
 	Timestamps
+	MachineReserve *MachineReserve `json:"machine_reserve,omitempty"`
 }
 
 type PartitionCapacity struct {
@@ -39,6 +42,8 @@ type PartitionCapacity struct {
 	ServerCapacities []ServerCapacity `json:"servers" description:"servers available in this partition"`
 }
 
+type MachineReserve map[string]int
+
 type ServerCapacity struct {
 	Size           string   `json:"size" description:"the size of the server"`
 	Total          int      `json:"total" description:"total amount of servers with this size"`
@@ -48,12 +53,17 @@ type ServerCapacity struct {
 	FaultyMachines []string `json:"faultymachines" description:"servers with issues with this size"`
 	Other          int      `json:"other" description:"servers neither free, allocated or faulty with this size"`
 	OtherMachines  []string `json:"othermachines" description:"servers neither free, allocated or faulty with this size"`
+	Reserved       int      `json:"reserved" description:"reserved machines"`
 }
 
 func NewPartitionResponse(p *metal.Partition) *PartitionResponse {
 	if p == nil {
 		return nil
 	}
+	mr := MachineReserve{}
+	for k, v := range p.MachineReserve {
+		mr[k] = v
+	}
 	return &PartitionResponse{
 		Common: Common{
 			Identifiable: Identifiable{
@@ -77,5 +87,6 @@ func NewPartitionResponse(p *metal.Partition) *PartitionResponse {
 			Created: p.Created,
 			Changed: p.Changed,
 		},
+		MachineReserve: &mr,
 	}
 }
diff --git a/spec/metal-api.json b/spec/metal-api.json
index 2ef213c1c..8ee5e8445 100644
--- a/spec/metal-api.json
+++ b/spec/metal-api.json
@@ -1837,6 +1837,12 @@
         "imageid"
       ]
     },
+    "v1.MachineReserve": {
+      "additionalProperties": {
+        "type": "integer"
+      },
+      "type": "object"
+    },
     "v1.MachineResponse": {
       "properties": {
         "allocation": {
@@ -2373,6 +2379,9 @@
           "type": "string",
           "uniqueItems": true
         },
+        "machine_reserve": {
+          "$ref": "#/definitions/v1.MachineReserve"
+        },
         "mgmtserviceaddress": {
           "description": "the address to the management service of this partition",
           "type": "string"
@@ -2421,6 +2430,9 @@
           "type": "string",
           "uniqueItems": true
         },
+        "machine_reserve": {
+          "$ref": "#/definitions/v1.MachineReserve"
+        },
         "mgmtserviceaddress": {
           "description": "the address to the management service of this partition",
           "type": "string"
@@ -2457,6 +2469,9 @@
           "type": "string",
           "uniqueItems": true
         },
+        "machine_reserve": {
+          "$ref": "#/definitions/v1.MachineReserve"
+        },
         "mgmtserviceaddress": {
           "description": "the address to the management service of this partition",
           "type": "string"
@@ -2607,6 +2622,11 @@
           },
           "type": "array"
         },
+        "reserved": {
+          "description": "reserved machines",
+          "format": "int32",
+          "type": "integer"
+        },
         "size": {
           "description": "the size of the server",
           "type": "string"
@@ -2624,6 +2644,7 @@
         "free",
         "other",
         "othermachines",
+        "reserved",
         "size",
         "total"
       ]