Slack vs Microsoft Teams: Which Should You Choose?

Pick Microsoft Teams if your company already licenses Microsoft 365, because at that point Teams is effectively bundled in and Slack becomes a line item you have to justify on top of a subscription you're already paying for. Pick Slack if you're not a Microsoft shop, or if your team lives in Slack Connect channels with clients and partners who aren't on your tenant. The real decision here is almost never about chat features: threading, channels, and search work well enough in both tools that a feature checklist rarely settles it. What settles it is procurement math and how much of your daily work already happens inside someone else's ecosystem. For the broader criteria first, see how to choose team chat software.

Neither tool is objectively better. Slack built the category and still leads on app ecosystem depth and cross-company collaboration. Microsoft Teams ships inside a productivity suite most mid-size and enterprise companies already buy, which changes the cost comparison before you evaluate a single feature. The rest of this guide covers what each platform is, the pricing story worth understanding in 2026, and which team profile fits which product.

What Slack is vs what Microsoft Teams is

Slack is a channel-based messaging tool built as a standalone product: you sign up, create channels, and everything else (video calls, file storage, workflow automation) layers on through native features or one of thousands of app integrations. It's best-of-breed by design, meant to sit inside whatever stack you already run.

Microsoft Teams is a chat and meetings product built inside Microsoft 365. A "Team" maps to a Microsoft 365 group and usually a SharePoint site behind the scenes, so channels, files, and Office documents share the same workspace instead of living in separate tools you connect yourself. Teams was built for people already opening Outlook, Word, and Excel every day, not as a standalone chat app that happens to also handle files.

Key Facts: Slack vs Microsoft Teams

• Microsoft Teams crossed 320 million monthly active users in October 2023, the last usage figure Microsoft has confirmed publicly.
• Microsoft's share of the worldwide unified communications and collaboration market reached 45.6% in 2024, per IDC data, up 2.4 points from the year before.
• More than 100,000 organizations now use Slack Connect to link channels across company lines, with nearly 80% of Fortune 100 companies among them, as of May 2026.
• Microsoft unbundled Teams from Office and Microsoft 365 worldwide on April 1, 2024, after a Slack antitrust complaint filed in 2020 triggered a formal European Commission investigation in July 2023. That case is why no-Teams SKUs exist today at a lower price.
• Slack's Free plan caps message history at 90 days and integrations at 10 apps, worth checking before you assume "free" means "unlimited."

Head to head on the things that decide it

Both tools cover the basics well: channels, threads, search, mobile apps. Where they diverge decides whether your team fights the tool daily or barely notices it.

The pattern holds: Slack wins on cross-company collaboration and app depth, what a best-of-breed messaging tool is built for. Teams wins on meetings, calling, and document handling, because it isn't really competing as a standalone chat app. It's inheriting capability from the rest of Microsoft 365.

Pricing compared

Pricing comparisons in this category go stale fast, especially on the Microsoft side, so here is what each vendor's own pricing page states today, checked in September 2026.

Slack pricing (slack.com/pricing):

Microsoft pricing (microsoft.com compare pages), all paid yearly on an auto-renewing annual subscription:

Here is the piece that changes the whole argument, easy to miss if you're working from an older article: Microsoft has folded Copilot into the Business Standard and Business Premium subscriptions, which now list as "with Copilot" at $23.50 and $32.00 per user per month, paid yearly. The $30/user/month figure that shows up in most Slack-versus-Teams comparisons is the Enterprise add-on, the rate an E3 or E5 seat pays, and it is not what a small or mid-size buyer pays. On the business side Microsoft lists the Copilot add-on at $18.00 per user per month paid yearly, a promotional rate down from $21.00 and running through December 31, 2026, or $25.20 month to month.

That matters because the historic argument, that Slack includes AI for free while Teams charges $30 extra, does not describe what an SMB buyer is quoted. Slack still includes conversation summaries, AI search, daily recaps, and file summaries from the Free tier up, with no separate AI license at all. Teams buyers on Business Standard or Business Premium are now paying for Copilot inside a bundled price instead of a bolt-on line item finance would flag on its own. Whether that's cheaper for you depends entirely on whether you needed those Office apps and Copilot access anyway.

One more detail worth noting: Microsoft sells a no-Teams variant of its two most common SKUs, $5.40 instead of $7.00 for Business Basic, and $20.30 instead of $23.50 for Business Standard. That $1.60 to $3.20 gap is roughly what Microsoft itself prices Teams at inside a bundle, a direct result of the EU antitrust case that forced the global unbundling (see Key Facts above). It's a useful anchor for what Teams actually costs you, closer to the real number than comparing a full Microsoft 365 subscription against a standalone Slack seat. It also reframes the comparison, because most Teams buyers were never buying Teams on its own. They were buying Microsoft 365 for email, Word, Excel, and OneDrive, and got Teams as part of that purchase.

Here is what those rates cost at two common team sizes, with the math shown.

Compared tier for tier, Slack Pro and Microsoft 365 Business Basic land close together, within about $30 a year at 10 seats. But that undersells the real question. If you already need email, Word, Excel, and OneDrive, Business Basic gives you Teams essentially for free on top of a purchase you were making anyway, while Slack Pro is a new, standalone cost. The comparison only favors Slack outright when your company genuinely isn't buying Microsoft 365 for anything else.

When Slack is the better choice

Slack tends to win when your team isn't already inside the Microsoft ecosystem, or when cross-company collaboration matters more than document integration.

• You're not a Microsoft shop. Google Workspace teams, or a mix of best-of-breed SaaS tools, don't need to adopt an entire ecosystem just to get a chat tool.
• You collaborate across company lines constantly. Slack Connect links your channels directly to a client's or partner's workspace, faster than juggling guest accounts for every external contact.
• Your team already lives in Salesforce, Jira, or GitHub. Slack's app ecosystem is the deepest in the category, and workflows built around those integrations tend to be more mature than Teams' equivalents.
• You want AI features without a separate line item. Slack's summaries, search, and recaps ship from the Free tier up, so you're not negotiating a Copilot SKU just to get them.

If your team already leans away from Microsoft, Slack needs less justification to earn its own line item on the budget.

When Microsoft Teams is the better choice

Teams tends to win when your company is already committed to Microsoft 365, or when meetings and document handling matter as much as chat.

• You already pay for Microsoft 365. This is the single biggest factor. If your company licenses Business Basic or above, Teams is close to free at the margin, and adding Slack on top means paying twice for overlapping functionality.
• You need meetings, calling, and webinars without a second vendor. Teams handles PSTN calling, town halls, and large webinars natively, where Slack requires pairing with Zoom or Google Meet for the same depth.
• Your team lives in Word, Excel, and PowerPoint. Documents open and co-edit inline inside Teams channels, backed by SharePoint and OneDrive, a workflow Slack doesn't attempt to replicate.
• You're a regulated company or large enterprise with an existing Microsoft footprint. Enterprise agreements that already include E3 or E5 licensing often make Teams the effectively-free option on a contract you've already signed.

If your company's software budget already runs through Microsoft, Teams rarely needs a separate business case to stay the default.

How to choose: a decision framework

Match your situation to the table below. When procurement and culture point in different directions, procurement usually wins.

For a category-agnostic version of this logic, how to choose team chat software walks through the criteria that matter across any team chat comparison. If your team is distributed across time zones, how to choose team chat for remote teams reweights those same criteria around async habits and searchable history, factors that matter less in a co-located office.

Frequently asked questions

Does Slack work if my company is a Microsoft shop?

Yes. Plenty of Microsoft 365 companies run Slack instead of or alongside Teams, especially engineering-heavy or SaaS-first teams that value Slack's app ecosystem over deep Office integration. Budget for it as a genuine additional cost, not something already covered by your Microsoft 365 subscription.

Is Microsoft Teams free?

There's a standalone free plan with basic chat, meetings, and calling. Most organizations get Teams bundled into a Microsoft 365 Business or Enterprise subscription instead, starting at $7.00 per user per month paid yearly for Business Basic. Check what your company is already licensed for before assuming you need a separate purchase.

Can Slack and Microsoft Teams work together?

Yes. Slack offers a Microsoft Teams interoperability integration, and third-party bridges like Mio can connect the two further. Running both fragments attention and doubles your chat spend, so treat interoperability as a bridge during a migration, not a permanent architecture.

Does either tool charge extra for AI features?

Slack doesn't. Its AI features (conversation summaries, AI search, daily recaps, file summaries) are included from the Free tier up, with a personal AI agent as the paid step up at Business+. Microsoft folds Copilot into the Business Standard and Business Premium tiers at $23.50 and $32.00 per user per month, or sells it as an $18/user/month add-on on lower tiers.

What's the real cost difference if I'm already paying for Microsoft 365?

Close to zero at the margin. If your company is already on Business Basic or above, Teams comes with that subscription. Adding Slack means paying its full per-seat price on top, which only makes sense if Slack's app ecosystem or external-collaboration features are worth that cost to your team.

Choosing the tool that fits how you already pay for software

The Slack vs Microsoft Teams question resolves faster than most software decisions, because procurement usually settles it before features do. If you're already paying for Microsoft 365, Teams is close enough to free that Slack needs a specific, defensible reason to sit on top of it: deeper external collaboration, a stronger app ecosystem, or a culture that doesn't fit inside a document-centric workspace. If you're not a Microsoft shop, that whole calculation disappears, and the decision comes down to which tool your team will actually use well.

What shouldn't drive the decision is an outdated assumption about pricing. The old argument that Teams charges $30 extra for AI while Slack includes it for free doesn't hold in that form anymore; Microsoft folded that cost into its bundled tiers. Verify today's numbers on both vendors' pricing pages before you sign anything, because this category reprices more often than most.

If you're still narrowing the category before committing to either vendor, how to choose team chat software is the right starting point. And before you sign either contract, write down what the tool has to connect to: the software integration requirements checklist covers the questions that decide whether a chat platform actually fits the rest of your stack.

Related reading

• How to choose team chat software
• How to choose team chat for remote teams
• How to choose an office suite
• How to choose shared inbox software
• How to choose project management software
• How to run a software trial
• SaaS vendor evaluation scorecard
• Software integration requirements: a buyer's checklist
• Notion vs ClickUp: which should you choose?
• Slack vs Microsoft Teams (tool-by-tool comparison)
• Best Slack alternatives
• Best Microsoft Teams alternatives