Comparison
Slack vs Microsoft Teams
This is not really a chat comparison. It is a question about which suite you already pay for.
The verdict
Microsoft Teams wins on cost for any company already buying Microsoft 365: Business Basic listed at $7.00 per user per month with Teams and $5.40 without on 21 August 2026, pricing Teams at roughly $1.60 a head. Slack Pro listed at $7.25 per user per month billed annually. Slack's case is its integration surface, external Slack Connect channels and daily working experience, not price.
- Teams inside M365
- ~$1.60 / user / mo
- Teams Essentials
- $4.00 / user / mo, annual
- Slack Pro
- $7.25 / user / mo, annual
- Checked
- 21 August 2026
The verdict
If your company already pays for Microsoft 365, use Teams and stop the evaluation. Microsoft's own price list makes the argument: on 21 August 2026, Microsoft 365 Business Basic listed at $7.00 per user per month with Teams included and $5.40 per user per month without it. The chat product is being sold to you for about $1.60 a head. Slack Pro at $7.25 is more than four times that for the same seat, and it does not come with Word, Excel, Outlook or a terabyte of storage.
If you are not on Microsoft 365, the comparison opens up. Teams Essentials at $4.00 per user per month is chat, calling and meetings without the Office apps, which is a real product and cheaper than Slack. Slack Pro at $7.25 buys a materially better daily experience, a much larger third-party app directory, and Slack Connect channels with other companies, which is the feature that most often makes the decision for agencies, investors and anyone whose work crosses org boundaries.
Slack's free tier deserves a warning rather than a recommendation. Ninety days of message history means the answer somebody gave in March is gone by July. Teams' free tier keeps history. For a small team that intends to stay free, that is the whole comparison.
Head to head
Read from slack.com/pricing and Microsoft's Teams plan comparison on 21 August 2026. All prices are annual-billing rates.
Slack
Microsoft Teams
- Free tier
90 days of message history
Free version with retained history and meeting limits
- Entry paid price
Pro $7.25 per user per month annually, $8.75 monthly
Teams Essentials $4.00 per user per month annually
- Inside a suite
Standalone
Business Basic $7.00 with Teams, $5.40 without, so Teams is about $1.60
- Next tier up
Business+ $15 annually, $18 monthly
Business Standard with Copilot $23.50 annually
- Third-party apps
Very large directory, and the default integration target for most SaaS
Growing, and strongest inside the Microsoft estate
- Cross-company channels
Slack Connect, widely used
External access and shared channels, more administratively involved
- Meetings and calling
Huddles and calls, adequate rather than a selling point
Full meeting platform, phone system available, the stronger product
- Compliance and eDiscovery
Available on higher tiers
Purview and the Microsoft compliance stack, hard to beat
- Best fit
Companies that live in chat and integrate many tools
Companies already on Microsoft 365, or that need serious meetings
Comparison of Slack and Microsoft Teams by What decides it.
Why teams still pay for Slack
The reasons are real, and none of them are price.
Slack's genuine advantages
- Channels with external partners that behave like internal channels
- The default place any SaaS vendor ships an integration first
- Search that people actually use, on paid tiers
- Threads that hold a conversation instead of scattering it
- Workflow Builder for small automations without engineering time
Microsoft Teams' genuine advantages
- Effectively bundled into a licence most companies already hold
- Meetings, webinars and telephony at a standard Slack does not match
- Files that live in SharePoint and OneDrive with the permissions already set
- Compliance, retention and eDiscovery through the Microsoft stack
- Free tier that does not delete your history after ninety days
Questions that decide it faster than a trial
Do you already pay for Microsoft 365?
If yes, the burden of proof is on Slack to justify a second bill. Sometimes it clears that bar. Usually it does not, and the honest answer is that people prefer Slack rather than that Slack is required.
How much of your work happens with people outside the company?
If a lot, Slack Connect is the strongest single argument in this comparison. Teams can do external access, and it is more administratively involved on both sides.
Do you run webinars or use a phone system?
If yes, Teams. The meeting and telephony gap is wide and Slack has never seriously contested it.
Is anyone relying on the free tier for a record?
If yes, not Slack. Ninety days of history is fine for banter and unsuitable for decisions.
A third option worth knowing about
Whichever you pick, the same thing happens: decisions get made in a channel and then have to be manually copied into a tracker by whoever remembers. Most of them are not. That loss is the actual cost of team chat and neither vendor treats it as their problem.
Polaris includes team chat alongside tasks and documents, and its Inbox is built around exactly that gap. A Slack message arrives as a prefilled task suggestion with the workstream, lane, labels and owner already filled in, waiting for one click. Signals become suggestions rather than silent tasks, so nothing is created behind your back and nothing is lost in scrollback either.
Slack is in the Polaris connections catalog, so this does not require leaving it. The software is free with no seats; billing is roughly two dollars per human-equivalent hour that an AI worker on your roster delivers, itemised on a work log you can challenge. Polaris is in free public beta with no customers yet.
Questions people ask
+Is Microsoft Teams free?
There is a free version of Teams with limits on meeting length and participants, and it retains message history rather than expiring it. Paid Teams starts at Teams Essentials, listed at $4.00 per user per month billed annually on 21 August 2026, and is also included in Microsoft 365 Business plans.
+Why does Microsoft sell Business Basic with and without Teams?
Microsoft unbundled Teams from its Microsoft 365 suites following regulatory pressure in Europe, and now lists both versions. On 21 August 2026 the difference was $7.00 with Teams against $5.40 without, which is the closest thing to a published standalone price for Teams inside a suite.
+Can you migrate Slack history into Microsoft Teams?
Yes, with third-party migration tools, and it is more work than it sounds. Channels, direct messages and files can be moved. Threading structure, reactions, custom emoji and app-generated messages transfer inconsistently, and message permalinks in old documents will break.
+How long does Slack keep messages on the free plan?
Ninety days. Older messages and files are not deleted but become inaccessible until you upgrade, at which point history returns. Teams that treat Slack as a searchable record need at least the Pro plan, listed at $7.25 per user per month annually as of 21 August 2026.
+Which one has better AI features?
Microsoft has the deeper integration through Copilot, which reads across mail, files, meetings and chat, and prices it accordingly: Business Standard with Copilot listed at $23.50 per user per month. Slack AI is narrower, focused on channel summaries and search. Both are additional cost rather than included capability.
Related
A Slack alternative where the message becomes a task, not scrollback
Slack is where the signal arrives. It is also where the signal goes to be forgotten by Thursday.
Slack pricing, checked August 2026
The one vendor here that bills per active user, which helps more than most people realise.
Connect Slack to Polaris
Six scopes, no access to direct messages, and a bot that only reads the channels somebody invited it into.
Replacing Notion and Slack
A stack with a writing tool and a talking tool, and no place where a piece of work has an owner and a date.
Replacing Jira and Slack
Engineering teams on Jira and Slack have a tracker, a chat tool, and specs living in ticket descriptions.
Replacing Linear and Slack
Issues in one place, everything anyone said about those issues in the other, and nothing written down.
Tool stack cost for a 25-person team
The size where paying monthly instead of annually costs $1,650 a year on its own.
Tool sprawl
The expensive part is not the licences. It is that nothing is authoritative any more.