diff --git a/cluster/gce/config-common.sh b/cluster/gce/config-common.sh
index 628ad582719..112c63a637c 100644
--- a/cluster/gce/config-common.sh
+++ b/cluster/gce/config-common.sh
@@ -98,6 +98,19 @@ function get-cluster-ip-range {
   echo "${suggested_range}"
 }
 
+# Calculate ip alias range based on max number of pods.
+# Let pow be the smallest integer which is bigger than log2($1 * 2).
+# (32 - pow) will be returned.
+#
+# $1: The number of max pods limitation.
+function get-alias-range-size() {
+  for pow in {0..31}; do
+    if (( 1 << $pow > $1 * 2 )); then
+      echo $((32 - pow))
+      return 0
+    fi
+  done
+}
 # NOTE: Avoid giving nodes empty scopes, because kubelet needs a service account
 # in order to initialize properly.
 NODE_SCOPES="${NODE_SCOPES:-monitoring,logging-write,storage-ro}"
diff --git a/cluster/gce/config-default.sh b/cluster/gce/config-default.sh
index 69516c1857e..eb2bd973d7b 100755
--- a/cluster/gce/config-default.sh
+++ b/cluster/gce/config-default.sh
@@ -289,8 +289,10 @@ ENABLE_RESCHEDULER="${KUBE_ENABLE_RESCHEDULER:-true}"
 ENABLE_IP_ALIASES=${KUBE_GCE_ENABLE_IP_ALIASES:-false}
 NODE_IPAM_MODE=${KUBE_GCE_NODE_IPAM_MODE:-RangeAllocator}
 if [ ${ENABLE_IP_ALIASES} = true ]; then
-  # Size of ranges allocated to each node. Currently supports only /32 and /24.
-  IP_ALIAS_SIZE=${KUBE_GCE_IP_ALIAS_SIZE:-/24}
+  # Number of Pods that can run on this node.
+  MAX_PODS_PER_NODE=${MAX_PODS_PER_NODE:-110}
+  # Size of ranges allocated to each node.
+  IP_ALIAS_SIZE="/$(get-alias-range-size ${MAX_PODS_PER_NODE})"
   IP_ALIAS_SUBNETWORK=${KUBE_GCE_IP_ALIAS_SUBNETWORK:-${INSTANCE_PREFIX}-subnet-default}
   # If we're using custom network, use the subnet we already create for it as the one for ip-alias.
   # Note that this means SUBNETWORK would override KUBE_GCE_IP_ALIAS_SUBNETWORK in case of custom network.
@@ -305,8 +307,10 @@ if [ ${ENABLE_IP_ALIASES} = true ]; then
   PROVIDER_VARS="${PROVIDER_VARS:-} ENABLE_IP_ALIASES"
   PROVIDER_VARS="${PROVIDER_VARS:-} NODE_IPAM_MODE"
   PROVIDER_VARS="${PROVIDER_VARS:-} SECONDARY_RANGE_NAME"
-  # Number of Pods that can run on this node.
-  MAX_PODS_PER_NODE=${MAX_PODS_PER_NODE:-110}
+elif [[ -n "${MAX_PODS_PER_NODE:-}" ]]; then
+  # Should not have MAX_PODS_PER_NODE set for route-based clusters.
+  echo -e "${color_red}Cannot set MAX_PODS_PER_NODE for route-based projects for ${PROJECT}." >&2
+  exit 1
 fi
 
 # Enable GCE Alpha features.
diff --git a/cluster/gce/config-test.sh b/cluster/gce/config-test.sh
index d11512ac32b..b800e855f82 100755
--- a/cluster/gce/config-test.sh
+++ b/cluster/gce/config-test.sh
@@ -296,8 +296,10 @@ ENABLE_RESCHEDULER="${KUBE_ENABLE_RESCHEDULER:-true}"
 ENABLE_IP_ALIASES=${KUBE_GCE_ENABLE_IP_ALIASES:-false}
 NODE_IPAM_MODE=${KUBE_GCE_NODE_IPAM_MODE:-RangeAllocator}
 if [ ${ENABLE_IP_ALIASES} = true ]; then
-  # Size of ranges allocated to each node. gcloud current supports only /32 and /24.
-  IP_ALIAS_SIZE=${KUBE_GCE_IP_ALIAS_SIZE:-/24}
+  # Number of Pods that can run on this node.
+  MAX_PODS_PER_NODE=${MAX_PODS_PER_NODE:-110}
+  # Size of ranges allocated to each node.
+  IP_ALIAS_SIZE="/$(get-alias-range-size ${MAX_PODS_PER_NODE})"
   IP_ALIAS_SUBNETWORK=${KUBE_GCE_IP_ALIAS_SUBNETWORK:-${INSTANCE_PREFIX}-subnet-default}
   # If we're using custom network, use the subnet we already create for it as the one for ip-alias.
   # Note that this means SUBNETWORK would override KUBE_GCE_IP_ALIAS_SUBNETWORK in case of custom network.
@@ -312,8 +314,10 @@ if [ ${ENABLE_IP_ALIASES} = true ]; then
   PROVIDER_VARS="${PROVIDER_VARS:-} ENABLE_IP_ALIASES"
   PROVIDER_VARS="${PROVIDER_VARS:-} NODE_IPAM_MODE"
   PROVIDER_VARS="${PROVIDER_VARS:-} SECONDARY_RANGE_NAME"
-  # Number of Pods that can run on this node.
-  MAX_PODS_PER_NODE=${MAX_PODS_PER_NODE:-110}
+elif [[ -n "${MAX_PODS_PER_NODE:-}" ]]; then
+  # Should not have MAX_PODS_PER_NODE set for route-based clusters.
+  echo -e "${color_red}Cannot set MAX_PODS_PER_NODE for route-based projects for ${PROJECT}." >&2
+  exit 1
 fi
 
 # Enable GCE Alpha features.