diff --git a/cluster/gce/coreos/helper.sh b/cluster/gce/coreos/helper.sh
index 3532fc2b14..275f1e764f 100755
--- a/cluster/gce/coreos/helper.sh
+++ b/cluster/gce/coreos/helper.sh
@@ -67,5 +67,6 @@ function create-master-instance() {
     --metadata-from-file \
       "kube-env=${KUBE_TEMP}/master-kube-env.yaml,user-data=${KUBE_ROOT}/cluster/gce/coreos/master.yaml,configure-node=${KUBE_ROOT}/cluster/gce/coreos/configure-node.sh,configure-kubelet=${KUBE_ROOT}/cluster/gce/coreos/configure-kubelet.sh,cluster-name=${KUBE_TEMP}/cluster-name.txt" \
     --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no" \
+    --boot-disk-size "${MASTER_ROOT_DISK_SIZE:-10}" \
       ${preemptible_master}
 }
diff --git a/cluster/gce/debian/helper.sh b/cluster/gce/debian/helper.sh
index ad1ac797b1..b0b10a1d17 100755
--- a/cluster/gce/debian/helper.sh
+++ b/cluster/gce/debian/helper.sh
@@ -54,6 +54,7 @@ function create-master-instance {
     --metadata-from-file \
       "startup-script=${KUBE_TEMP}/configure-vm.sh,kube-env=${KUBE_TEMP}/master-kube-env.yaml,cluster-name=${KUBE_TEMP}/cluster-name.txt" \
     --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no" \
+    --boot-disk-size "${MASTER_ROOT_DISK_SIZE:-10}" \
     ${preemptible_master}
 }
 
diff --git a/cluster/gce/trusty/helper.sh b/cluster/gce/trusty/helper.sh
index 529b472716..451c3c64fd 100755
--- a/cluster/gce/trusty/helper.sh
+++ b/cluster/gce/trusty/helper.sh
@@ -95,5 +95,6 @@ function create-master-instance {
     --can-ip-forward \
     --metadata-from-file \
       "kube-env=${KUBE_TEMP}/master-kube-env.yaml,user-data=${KUBE_ROOT}/cluster/gce/trusty/master.yaml,configure-sh=${KUBE_ROOT}/cluster/gce/trusty/configure.sh,cluster-name=${KUBE_TEMP}/cluster-name.txt${image_metadata}" \
-    --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no"
+    --disk "name=${MASTER_NAME}-pd,device-name=master-pd,mode=rw,boot=no,auto-delete=no" \
+    --boot-disk-size "${MASTER_ROOT_DISK_SIZE:-10}"
 }
diff --git a/cluster/gce/util.sh b/cluster/gce/util.sh
index bec2074ed0..bee88a57bf 100755
--- a/cluster/gce/util.sh
+++ b/cluster/gce/util.sh
@@ -624,6 +624,18 @@ function create-network() {
   fi
 }
 
+# Assumes:
+#   NUM_NODES
+# Sets:
+#   MASTER_ROOT_DISK_SIZE
+function get-master-root-disk-size() {
+  if [ "$NUM_NODES" -le "1000"]; then
+    export MASTER_ROOT_DISK_SIZE="10"
+  else
+    export MASTER_ROOT_DISK_SIZE="50"
+  fi
+}
+
 function create-master() {
   echo "Starting master and configuring firewalls"
   gcloud compute firewall-rules create "${MASTER_NAME}-https" \
@@ -667,6 +679,9 @@ function create-master() {
 
   create-certs "${MASTER_RESERVED_IP}"
 
+  # Sets MASTER_ROOT_DISK_SIZE that is used by create-master-instance
+  get-master-root-disk-size
+
   create-master-instance "${MASTER_RESERVED_IP}" &
 }