Microsoft 365 storage and OneDrive costs rarely make the agenda until a quota fills or an add on charge appears on the invoice. For most organisations storage is bundled generously enough that it never becomes a problem. But the bundle has edges, and three things push firms over them: unmanaged data growth, the SharePoint pooled storage model, and add on purchases made to solve a problem that governance would have solved for free. Understanding where the included storage ends is the whole game.
As an independent, buyer side advisor with no Microsoft relationship and no reseller margin, we have no interest in selling you more capacity. This guide explains what storage comes with your plans, where the paid extras begin, and the governance moves that keep storage from becoming a creeping cost. It sits within the wider work of digital workplace cost optimization, where storage is one of the quieter sources of drift.
Microsoft 365 storage and OneDrive costs: what is included
Microsoft 365 storage comes in two main pools: OneDrive for individual users and SharePoint for shared and team content. Each user plan includes a OneDrive allocation, and the organisation gets a shared SharePoint pool that grows with the number of licensed users.
OneDrive per user storage
Most enterprise and business plans include 1 terabyte of OneDrive storage per user as standard (source: Microsoft OneDrive service description, microsoft.com, as of June 2026). For some plans and seat counts Microsoft will increase this beyond 1 terabyte on request, subject to its own conditions. For the overwhelming majority of users 1 terabyte is far more than they will ever use, which means OneDrive is rarely where the cost problem lives.
SharePoint pooled storage
SharePoint is different and is where most storage pressure builds. The organisation receives a base amount of pooled SharePoint storage plus an allocation per licensed user. As of June 2026 Microsoft provides 1 terabyte of base storage per organisation plus 10 gigabytes per licensed user, drawn from a shared tenant pool (source: Microsoft SharePoint limits and service description, microsoft.com, as of June 2026). Because it is pooled, heavy use by a few teams can consume the shared allowance, and that is when the add on conversation starts.
Where the paid extras begin
When the SharePoint pool fills, Microsoft sells additional storage per gigabyte per month as an add on. The per gigabyte price is modest on its own, but at scale and over time it becomes a recurring line that, once added, tends never to be reviewed. This is the classic add on trap: a tactical purchase to clear an immediate problem that then sits on the bill indefinitely. Our guide on Microsoft 365 add ons you may not need covers the wider pattern.
| Storage type | What is included |
|---|---|
| OneDrive per user | 1 terabyte per user on most enterprise and business plans |
| SharePoint base | 1 terabyte per organisation |
| SharePoint per user | 10 gigabytes per licensed user, added to the shared pool |
| Additional SharePoint | Sold per gigabyte per month as a paid add on |
Storage allowances and add on pricing are from the Microsoft OneDrive and SharePoint service descriptions at microsoft.com, as of June 2026. Microsoft revises these allowances periodically, so confirm against the current service description and your own agreement.
Why storage costs creep up
Storage spend rarely jumps. It creeps, for three reasons. First, data is never deleted. Old projects, departed employees, and duplicate files accumulate because nobody owns cleanup. Second, the pooled model means a few heavy teams can pull the whole organisation toward the add on threshold. Third, the per gigabyte add on is cheap enough to approve without thought, so it gets bought rather than questioned. None of these is dramatic, which is exactly why they go unmanaged. The same dynamic drives the wider problem described in common Microsoft 365 licensing mistakes.
The governance moves that keep storage cheap
Most storage add on spend is avoidable with light governance. Before buying more capacity, work the pool you already have.
Reclaim storage from departed employees. When someone leaves, their OneDrive and mailbox content lingers unless a retention and deletion policy handles it. A clear offboarding process recovers meaningful space at no cost. Set retention policies that delete content nobody is required to keep, rather than letting everything accumulate forever. Identify the heavy teams pulling on the shared pool and address their data practices directly. And review the SharePoint pool usage before approving any per gigabyte add on, because the answer is often to clean up rather than to buy.
For organisations with genuine large scale data needs, archival and tiered storage approaches can move cold data to cheaper homes rather than paying premium add on rates to keep everything in the primary pool. That is a design decision worth making deliberately rather than defaulting into the add on.
Where to start
Start by checking your actual SharePoint pool consumption against your allowance, and your OneDrive usage against the per user terabyte. Most firms find they are nowhere near the limits, in which case storage is a non issue to monitor rather than a cost to cut. Those approaching the threshold should clean up and set retention before buying a single gigabyte. Storage is one of the easiest costs to keep low, but only if someone owns it before the add on charge appears rather than after.