Storage is limited in GiB, not only counted

An account keeps up to 500 GiB in all with credit (50 GiB without): snapshots, images, volumes, volume backups and paused or stopped sandboxes, measured as they are billed; snapshots up to 250 GiB of it (20 GiB without). Past a limit nothing is deleted or stopped: a new snapshot, image, backup or volume is refused with quota_exceeded, naming the limit, until there is room. An account that already stored more than a limit when it began has what it stored then as that limit. Both are on the Limits page and in GET /v1/limits. See limits.