Microsoft 365 Outage Cost Calculator
The Microsoft 365 outage that began on 12 November 2026 started with Exchange Online mailbox access failures in the Americas, then affected Outlook, Teams, SharePoint, Copilot and Microsoft Defender XDR in multiple regions, per Microsoft and press reports. Microsoft said it is not aware of malicious activity causing it and will publish a post-incident report. Use this calculator to put a number on what it cost your organization, and to see whether the uptime tiers in Microsoft's SLA might support a service credit claim. Read what we know in our Microsoft 365 outage briefing.
1. The outage
People who could not work normally.
Used for the SLA uptime maths. Blank = same as affected.
Default for every service; override per service below.
Salary plus benefits and overhead, per hour. Use your own figure.
Sales or billable work that stops while email and Teams are down.
Used for the service credit estimate.
November has 30.
Labels only; no conversion.
2. Which services were down
“% of work blocked” is how much of an affected user's output stops while that service is down. The defaults are our assumptions for a typical office worker, not measured figures: change them to fit your organization.
Exchange Online also has separate email delivery time and delivery service levels; one Incident gives one claim per service.
SharePoint Online and OneDrive for work or school are separate sections of the SLA with the same tiers.
Uptime is measured on prompts, not hours, so hours down cannot give an estimate. Enter the share of prompts that failed this month if you know it.
The SLA has no section named Defender XDR. The estimate uses the Defender for Endpoint portal service level, measured per tenant, not per user. Check which Defender products you license.
Enter affected users and hours down to see the estimate. Nothing you type is sent to us.
About the service credit estimate
This is an estimate, not advice and not a promise that a credit is owed. It applies the tiers in Microsoft's Service Level Agreement for Microsoft Online Services (WW), November 1, 2026 to your inputs. Uptime is a calendar-month figure; for Exchange, Teams, SharePoint and OneDrive Microsoft measures it in user-minutes: (user minutes − downtime user minutes) ÷ user minutes × 100. Each service has its own definition of downtime, so a service that was slow but usable may not count.
The “indicative credit” column multiplies the tier by your whole monthly licence spend, so it is an upper bound: the real credit applies only to the fees for the affected service. The headline figure is the single largest service, not a sum.
- Credits are not automatic. You submit a claim to Microsoft customer support with a description of the Incident, the time and duration of downtime, affected resource names, the number and locations of affected users, and the errors seen. Claims missing that information are rejected.
- For Microsoft 365 services the claim must reach Microsoft by the end of the month after the month of the Incident (the SLA example: an Incident on February 15 needs the claim by March 31). For an Incident in November 2026, that is the end of December 2026.
- Microsoft decides whether a credit is owed, typically within 45 days of receiving the claim, and you must be in compliance with your agreement.
- Credits apply per service, to the fees paid for the service whose service level was missed, at most one credit per service per month, and never more than that service's monthly fees. If the services were bought as separate services (not a suite), each can be claimed separately.
- Credits are the sole remedy under the SLA and do not compensate lost revenue, operational costs or indirect losses. Some purchase routes (Open, Open Value) are credited in service days instead of fees.
- Microsoft's outage communications are not a confirmation that a service level was missed or that a credit is owed.
Tiers and downtime definitions used
- Exchange Online: below 99.9% = 25%, below 99% = 50%, below 95% = 100%. Downtime: Any period of time when users are unable to send or receive email with Outlook Web Access. There is no Scheduled Downtime for this service.
- Microsoft Teams: below 99.9% = 25%, below 99% = 50%, below 95% = 100%. Downtime: Any period of time when end users are unable to conduct instant messaging conversations or initiate online meetings.
- SharePoint Online (OneDrive for work or school has the same tiers): below 99.9% = 25%, below 99% = 50%, below 95% = 100%. Downtime: SharePoint Online: users unable to read or write any portion of a site collection they have permission for. OneDrive: users unable to view or edit files in their OneDrive storage.
- Microsoft 365 Copilot: below 99.5% = 25%, below 99% = 50%, below 95% = 100%. Downtime: A licensed user submits a valid prompt in Copilot Chat in the Microsoft 365 Copilot app and receives an unsuccessful response due to a server-side error from the LLM.
- Microsoft Defender for Endpoint (nearest named section): below 99.9% = 10%, below 99% = 25%. Downtime: Defender for Endpoint: the customer is unable to access any portion of the Defender for Endpoint portal they have permissions for, with a valid active licence.
Read 2026-11-13. Microsoft updates the SLA; check the current edition before you file a claim.
The breakdown, your inputs and the SLA claim notes, ready for a post-incident review or a finance note.
TL;DRWhat this calculator does
4 points
- Enter affected users, hours down, a loaded hourly cost and which services failed (Exchange/Outlook, Teams, SharePoint/OneDrive, Copilot, Defender XDR).
- You get productivity cost, revenue at risk, a total and a per-service breakdown. The "% of work blocked" defaults are our assumptions, clearly labelled, and you can change every one.
- The service credit estimate applies the uptime tiers in Microsoft's Service Level Agreement for Microsoft Online Services (November 1, 2026 edition) to your inputs. It is an estimate, not advice: credits need a claim from you within Microsoft's window and Microsoft decides.
- Free to use, signed out too. Everything runs in your browser and nothing is sent to us. Markdown and CSV exports of the breakdown are available with a paid plan.
Frequently asked questions
How do I calculate the cost of a Microsoft 365 outage?
Multiply affected users by hours down by a fully loaded hourly cost per user, then by the share of their work that actually stopped. Do it per service, because losing Teams for an hour does not stop as much work as losing email and files together. Add any revenue that could not be earned while the services were down. The calculator does this and caps the total so no one loses more than all of their time.
Does Microsoft give service credits for a Microsoft 365 outage?
The Service Level Agreement for Microsoft Online Services sets a monthly uptime commitment per service. For Exchange Online, Microsoft Teams, SharePoint Online and OneDrive for work or school, uptime below 99.9% earns a 25% credit, below 99% earns 50% and below 95% earns 100% of the fees for that service (November 1, 2026 edition). Credits are not automatic: you must submit a claim and Microsoft decides whether one is owed.
What is the deadline to claim a Microsoft 365 SLA credit?
For Microsoft 365 services the SLA says Microsoft must receive the claim, with all required information, by the end of the month after the month in which the Incident happened. For an Incident in November 2026 that means the end of December 2026. Check the current SLA edition and your agreement before relying on that date.
How is Microsoft 365 uptime calculated for the SLA?
For Exchange, Teams, SharePoint and OneDrive it is measured in user-minutes over the calendar month: total user minutes minus downtime user minutes, divided by total user minutes, times 100. So a short outage that hits a small share of your users may not drop uptime below 99.9%, while a long one that hits everyone can. Microsoft 365 Copilot is measured on failed prompts instead of time.
What happened in the 12 November 2026 Microsoft 365 outage?
Per Microsoft and press reports, it began on 12 November 2026 with Exchange Online mailbox access failures in the Americas, then affected Outlook, Teams, SharePoint, Copilot and Microsoft Defender XDR in multiple regions. Microsoft said it is not aware of malicious activity causing it and will publish a post-incident report. This calculator does not assume a cause or a duration: enter your own figures.
Is my data sent anywhere?
No. The calculation runs in your browser. Your inputs are saved in this browser's local storage so you can come back to them, and clearing site data removes them.
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