What it is
A Standard SKU public IP address with no ipConfiguration, meaning it is not associated with any network interface, gateway, or load balancer. It routes traffic for nothing, but a Standard IP is always allocated and always billed.
Why it happens
Standard public IPs are statically allocated by design and bill from the moment they exist until they're deleted, attached or not. They get stranded when a load balancer is rebuilt, a VM is deleted, or a gateway is migrated, and the IP is left behind so the old address can be "kept just in case."
Any single one is cheap, which is exactly why nobody cleans them up. They accumulate quietly across subscriptions.
What it costs / blast radius
Each idle Standard static IP is about $3.65/month at list price, roughly $44/year. (List price; bundled IPs on some SKUs differ.) The cost story here isn't one IP, it's the dozens that pile up across a large estate, plus the address-space clutter that makes every network review slower.
See it
Resources
| where type =~ 'microsoft.network/publicipaddresses'
| where isnull(properties.ipConfiguration)
| project name, resourceGroup, subscriptionId,
sku = sku.name, allocation = properties.publicIPAllocationMethodaz network public-ip delete \
--name pip-prod-eastus-04 --resource-group rg-prodHow StratoLens helps
StratoLens surfaces every unassociated public IP across every subscription in one list, so the long tail of $44/year strays gets cleaned up in one pass instead of never. It's the kind of low-stakes, high-volume waste that only gets fixed when something is watching for it continuously.