<p>I couldn't find useful information from:</p>

<pre><code>gcloud container clusters describe CLUSTER_NAME
</code></pre>

<p>or from</p>

<pre><code>gcloud container node-pools describe POOL_NAME --cluster CLUSTER_NAME
</code></pre>

<p>It is easy to scale up/down using <code>gcloud</code> tool though:</p>

<pre><code>gcloud container clusters resize [CLUSTER_NAME] --node-pool [POOL_NAME] \
    --size [SIZE]
</code></pre>

<p>But how can I know beforehand what is the size of my node-pool? </p>

Montenegrodr
<p>I do not agree with the current answer because <strong>it only gives the total size of the cluster</strong>.</p>

<p>The question is about <strong>node-pools</strong>. I actually needed to find out the size of a pool so I give you my best shot after many hours of searching and thinking.</p>

<pre><code>read -p 'Cluster name: ' CLUSTER_NAME
read -p 'Pool name:    ' POOL_NAME

gcloud compute instance-groups list \
 | grep "^gke-$CLUSTER_NAME-$POOL_NAME" \
 | awk '{print $6}';
</code></pre>

<p>The <code>gcloud</code> command returns 6 columns: 1-name, 6-group-size.
The name of the instance group is predictable which lets me filter by that line with <code>grep</code>.
Lastly, select the 6th column.</p>

<p>Hope this helps someone else save some time.</p>

<hr>

<p>For some reason I overlooked the not-so-obviuos from <a href="https://cloud.google.com/kubernetes-engine/docs/tutorials/migrating-node-pool" rel="nofollow noreferrer">Migrating workloads to different machine types</a></p>

<pre><code>kubectl get nodes -l cloud.google.com/gke-nodepool=$POOL_NAME -o=name \
  | wc -l
</code></pre>
