True cost comparison — not just what the pricing page says
Quick Verdict
Slack saves you 100%
Best for Slack
Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-ons (Rooms, Phone, W
Best for Microsoft Teams
Team messaging and collaboration hub. Free plan has a 90-day message history limit that forces upgra
Team messaging and collaboration hub. Free plan has a 90-day message history lim...
Advertised
$0
/month
True Cost
$8
/month (typical)
90-Day Message History Limit
Free plan deletes message access after 90 days. Your team's entire knowledge base disappears quarter...
Per-User Cost at Scale
A 100-person company on Pro pays $875/mo ($10,500/yr). Business+ is $1,250/mo ($15,000/yr). The per-...
Slack Connect External Channels
Connecting with external organizations requires Pro ($8.75/user/mo) minimum. Free plan has no extern...
$7/mo annual
Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-...
Advertised
$4
/month
True Cost
$74
/month (typical)
Teams Phone System
Voice calling requires Teams Phone at $8/user/mo + calling plan $12/user/mo. Total: $20/user/mo for ...
Teams Rooms
Conference room integration: $40/room/mo for Teams Rooms Pro. 10 rooms = $400/mo....
Teams Premium
AI meeting recap, custom branding, advanced webinars: $10/user/mo add-on. Not included in any M365 p...
Microsoft Teams advertises $4/mo. Slack advertises $0/mo.
Microsoft Teams has 3 documented hidden fees. Slack has 3.
Microsoft Teams confidence: 76%. Slack confidence: 83%.
| Metric | Slack | Microsoft Teams | Winner |
|---|---|---|---|
| Advertised Price | $0/mo | $4/mo | Slack |
| True Monthly Cost | $8/mo | $74/mo | Slack |
| Hidden Fee Total | +$8/mo | +$70/mo | Slack |
| # Hidden Fees | 3 | 3 | Slack |
| Confidence Score | 83% | 76% | Slack |
| Pricing Tiers | 4 | 0 | — |
| Affiliate Program | No public affiliate program | None | — |
Slack advertises $0/mo and Microsoft Teams advertises $4/mo. However, when you include hidden fees, Slack has 3 documented hidden fees adding +$8/mo, while Microsoft Teams has 3 hidden fees adding +$70/mo. Based on true cost, Slack is typically 100% cheaper.
Slack has 3 documented hidden fees: 90-Day Message History Limit, Per-User Cost at Scale, Slack Connect External Channels. These add approximately +$8/mo on top of the $0/mo advertised price.
Microsoft Teams has 3 documented hidden fees: Teams Phone System, Teams Rooms, Teams Premium. These add approximately +$70/mo on top of the $4/mo advertised price.
Choose Slack if: Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-ons (Rooms, Phone, W. Choose Microsoft Teams if: Team messaging and collaboration hub. Free plan has a 90-day message history limit that forces upgra. The right choice depends on your team size, usage volume, and which features you need most.
This comparison is based on manual research of official pricing pages, terms of service, and user reports. Slack data has a 83% confidence score and Microsoft Teams has 76%. Prices were last verified in April 2026. For the most accurate estimate, enter your specific usage in our calculator.
Enter your usage to see personalized pricing for both tools
Use Free Calculator