Pooled tenant storage is 1 TB plus 10 GB per licensed seat, and every gigabyte past it bills at $0.20 a month with no warning. Meanwhile version history routinely accounts for 30–70% of what's stored, both recycle bins count against quota, and terabytes sit in leavers' OneDrive.
One month the tenant is fine; the next there's an overage charge on the Microsoft invoice. No alert, no threshold, no owner - just $0.20 per gigabyte per month, compounding quietly.
SharePoint stores the full file size for every version it keeps. Across a few thousand co-authored documents that becomes a double-digit share of everything you store, and no site metric breaks it out.
OneDrive accounts belonging to people who left, Teams sites whose last owner was offboarded, private and shared channel sites, and recycle bins full of content users forgot about months ago.
Three numbers decide your storage bill: the quota your licenses earn, the rate charged past it, and how much of what's stored is a copy of something else.
Every Microsoft 365 tenant gets 1 TB of SharePoint Online storage plus 10 GB for each licensed seat. OneDrive for Business quota sits on top of that, per user.
It's a pool, not a per-site allowance - so one team's version history quietly spends the headroom another team needed. And because the quota is derived from seat count, it shrinks the moment you right-size licensing.
1 TB + 10 GB per licensed seat · overage at $0.20 per GB / month
$0.20 per GB per month is about $2,400 per terabyte per year, charged automatically with no alert, no threshold and no approval step.
There's no incident to escalate and no owner to notify, which is why an overage that started eighteen months ago is usually still running.
Version history first: SharePoint stores the full file size for every version it keeps, and the default is 500 versions with no expiry. Then both recycle bin stages, which count against quota for the full 93 days. Then leavers' OneDrive accounts, ownerless Teams and private-channel sites, and cold project sites still priced as live storage.
Almost none of it is work anybody is currently doing - which is why reclaiming it rarely involves asking a person for permission to delete their files.
The biggest site is often the cheapest to leave alone. Sort by what each gigabyte costs you and how hard it is to reclaim.
Purview retention policies, labels, litigation and eDiscovery holds get mapped before anything is a candidate. Trimmed versions can't be recovered.
Usually the largest single block. Set limits per library class - working libraries low, general business moderate, legal and records untouched.
First and second stage both bill for 93 days. Space reclaimed equals the deleted size exactly, and users notice nothing.
Departed employees' OneDrive, Teams sites with no surviving owner, private-channel site collections nobody reviews. Reassign, archive or release.
Microsoft 365 Archive is roughly $0.05 per GB against $0.20 for overage. Trim before archiving so you're not paying to store overhead.
Examples rather than the catalogue - a sample of what the platform reads across your sites, libraries, OneDrives and quota, ordered by dollars per gigabyte.
Tenant storage is pooled, priced per gigabyte per month once you cross the line, and invoiced without so much as an alert. Meanwhile the majority of what's stored isn't work anybody is doing - it's copies, versions and content whose owner left the company.
Which SharePoint document libraries have never had a version limit applied, how much quota the excess consumes, and what Automatic mode would return - all versions from the last 30 days, progressively thinned after that. Legal, finance and records libraries keep their own thresholds.
Site metrics report total size and never break out the versions inside it. Trimmed versions bypass the recycle bin and can't be recovered.
Every OneDrive for Business account whose owner has left, cross-referenced against offboarding dates, Purview retention policies and eDiscovery holds. Content is preserved where it must be and released where it should never still be billing.
Orphaned content has no owner to raise a flag, and deleting it wrong has retention consequences most teams won't gamble on.
Group-connected SharePoint sites whose owners have all been offboarded, private and shared channel sites that each get their own site collection, and sites tied to projects that closed two years ago but still sit in the live tier.
Private-channel sites rarely appear in the site list anybody actually reviews, so nothing about them looks like a cost.
First-stage and second-stage recycle bins count against site quota for the full 93-day window, and second-stage content is effectively invisible to the people who deleted it. Reclaimed space equals the deleted size exactly.
The storage figure in the admin center already includes both stages. Nothing in it says how much.
Microsoft 365 Archive runs at roughly $0.05 per GB per month against $0.20 for overage - up to 75% off cold data that stays searchable, eDiscovery-compliant and permission-intact. Weighed against the per-action reactivation fee for sites that might come back.
Archiving before trimming versions means paying archive rates on overhead you could have removed first.
Pooled tenant storage is 1 TB plus 10 GB per licensed seat, so every license you right-size takes quota away with it. We model the storage consequence of the licensing plan before either one is proposed.
The two numbers live in different admin centers, and nothing reconciles them for you.
Reclaim is ordered by dollars per gigabyte, checked against Purview retention policies and legal holds before anything moves, and weighed archive-versus-delete on cost. Then we do the cleanup: version policies applied per library type, both bin stages cleared, cold sites archived, ownership reassigned, and tenant-level defaults set so the footprint doesn't rebuild.
Figures on this page describe an illustrative 5,200-seat tenant at published overage rates, shown for illustration. Your audit replaces them with your own numbers, tied to named sites, libraries and OneDrive accounts.
Every storage finding arrives as a decision with a target, a retention check and an annual value - ordered by what returns the most quota per hour of work.
Version overhead measured per library. Legal, finance and records libraries are excluded and keep their own retention thresholds.
Cross-checked against offboarding dates, retention policies and eDiscovery holds. Anything on hold stays exactly where it is.
Versions trimmed first, so you don't pay archive rates on overhead. Content stays searchable, compliant and permissioned.
Group ownership reassigned where the site is still in use; archived where last activity predates the project's close.
Both stages emptied once the 93-day window and hold status are confirmed. Space reclaimed equals the deleted size exactly.
Every line in a Chronom report is a decision with an owner, a SKU and a dollar figure. Nothing is left for you to go and find out.
“Low Teams usage detected” - a fact you now have to interpret
An alert queue that grows faster than you can triage it
A dashboard that hands the analysis back to you
Cleanup without governance is a one-time fix. Within a year version histories stack back up, bins refill, and new inactive sites accumulate with nobody assigned to them. Chronom keeps reading the footprint so the overage doesn't come back.
Consumption is tracked against the quota your current licensing actually earns you, so you see the gap closing weeks before an overage charge appears on the invoice.
Tenant-level version limits and site quotas go in behind the cleanup, so a library created next quarter starts at a sensible default instead of 500 versions with no expiry.
Sites and OneDrives that lose their last owner are flagged as they happen, while somebody still remembers what the content was for and whether it needs to be kept.
Before you add paid storage, you can see exactly how much reclaimable space is sitting in versions, bins and cold sites - and what each gigabyte of it costs to leave alone.
Tenant storage is pooled: roughly 1 TB plus 10 GB per licensed user, with OneDrive quota on top per seat. Once the pool is exhausted, additional SharePoint Online storage bills at $0.20 per GB per month - about $2,400 per TB per year - and it appears on the invoice without an alert or an approval step. That's what makes it the quietest line on a Microsoft bill: nothing escalates, it just recurs.
In this order, because the sequence changes the total. Rank sites and libraries by dollars per gigabyte rather than by size. Clear retention policies and legal holds out of the way first. Trim version history, which is usually the single largest block and the cheapest to remove. Empty both recycle bin stages. Resolve leavers' OneDrive accounts and ownerless Teams sites. Then archive what's cold at roughly $0.05 per GB instead of paying $0.20 for it, and only buy extra quota if a real gap remains. Done in that order most tenants recover up to 30% of the footprint without deleting a single working document.
It's safe when the policy is set per library type before the job runs, and unforgiving if it isn't - deleted versions bypass both recycle bin stages and cannot be recovered. Chronom classifies libraries first: 10-20 versions for working and scratch content, around 50 for general business content, and full retention for legal, finance and records libraries. Anything covered by a retention policy or legal hold is excluded before a single version is touched.
It stays exactly where it is. Every reclaim candidate is checked against Purview retention policies, retention labels, litigation and eDiscovery holds before it appears in the plan, not after you approve it. Where content must be kept but doesn't need to sit in the live tier, the recommendation becomes archive rather than delete - it remains searchable and eDiscovery-compliant with its permission structure intact.
It depends on the dollars per gigabyte and the odds of reactivation, which is exactly the comparison we run. Microsoft 365 Archive is around $0.05 per GB per month against $0.20 for overage, so cold-but-required content is far cheaper archived - but reactivation carries a per-action fee, so it suits sites with genuinely low reactivation frequency. Version history gets trimmed before anything is archived, so you're not paying archive rates on overhead.
It will, if nobody models it first. Pooled storage is a function of licensed seats, so a clean licensing win can hand part of itself back at per-gigabyte overage rates. That arithmetic is why Chronom runs licensing and storage together: the licensing plan is checked against your storage headroom before it's proposed, and the storage cleanup is sequenced to create the headroom the licensing change needs.
No. The connection is read-only through the Microsoft Graph API and reads usage signals and metadata - site and library sizes, version counts, ownership, last-activity dates, retention state. Never the contents of documents, mailboxes or messages. Nothing in the tenant changes until you approve a specific action, and Chronom is SOC 2 Type II compliant.
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