Estimated monthly cost comparison — not just the headline price
Prices change often — confirm on the vendor's site before buying. Report incorrect pricing →
Quick Take
Slack has the lower estimated monthly cost (~89%)
Based on advertised price plus documented recurring fees, not your exact usage.
Best for Microsoft Teams
Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-ons (Rooms, Phone, W
Best for Slack
Team messaging and collaboration hub. Free plan has a 90-day message history limit that forces upgra
Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-...
Advertised
$4
/month
Estimated monthly cost
$74
/month (illustrative)
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...
Team messaging and collaboration hub. Free plan has a 90-day message history lim...
Advertised
$0
/month
Estimated monthly cost
$8
/month (illustrative)
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
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 | Microsoft Teams | Slack | Winner |
|---|---|---|---|
| Advertised Price | $4/mo | $0/mo | Slack |
| Estimated Monthly Cost | $74/mo | $8/mo | Slack |
| Recurring Extra Fees | +$70/mo | +$8/mo | Slack |
| One-Time Costs | $0 | $0 | — |
| # Documented Fees | 3 | 3 | — |
| Pricing Tiers | 0 | 4 | — |
| Affiliate Program | None | No public affiliate program | — |
Microsoft Teams advertises $4/mo and Slack advertises $0/mo. Microsoft Teams has 3 documented extra fees (recurring: +$70/mo), while Slack has 3 (recurring: +$8/mo). On these illustrative assumptions, Slack has the lower estimated monthly cost (about 89% less). Your real cost depends on seats and usage — use the calculator for your numbers.
Microsoft Teams has 3 documented extra fees: Teams Phone System, Teams Rooms, Teams Premium. Recurring fees add roughly $70/mo on top of the $4/mo advertised price.
Slack has 3 documented extra fees: 90-Day Message History Limit, Per-User Cost at Scale, Slack Connect External Channels. Recurring fees add roughly $8/mo on top of the $0/mo advertised price.
Choose Microsoft Teams if: Bundled with Microsoft 365. 'Free' for M365 subscribers, but standalone and add-ons (Rooms, Phone, W. Choose Slack 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 compiled from public vendor pricing pages and documentation. It uses illustrative assumptions (see "Cost Comparison Summary"), not your exact seats or usage, and vendor prices change often. Confirm current prices on each vendor's site, and use our calculator with your own usage for a closer estimate. Spotted an error? Email hello@trulycritic.com.
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