Carbon Footprint of Slack
IdleForest models one hour of Slack use at about 30g of CO2.
Slack is mostly a text and notification workflow, but its footprint rises with long active desktop sessions, file previews, huddles, clips, and video calls.
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How this Slack estimate is built
The estimate treats Slack as an active work tool with a lower hourly footprint than video meetings, but higher overhead than a static page because it stays synced across devices and workspaces.
- The 30gCO2e/hour figure reflects active chat, file previews, notifications, and occasional voice or video collaboration.
- The yearly estimate uses 30gCO2e/hour x 2 hours/day x 365 / 1000 = 21.9kgCO2e/year.
- Tree offset math rounds 21.9kgCO2e/year divided by 20kgCO2e per tree-year up to 2 trees.
Calculation proof
How the estimate is calculated
Annual footprint formula
30g CO2e/hour x 2h/day x 365 / 1000 = 21.9kg CO2e/year
Tree offset formula
ceil(21.9kg CO2e / 20 kg CO2e per tree-year) = 2 rounded up
Source basis: This estimate combines the app's modeled hourly footprint, usage assumption, methodology notes, and linked research sources. It is directional and should be read as a transparent consumer estimate, not a vendor emissions disclosure.
What drives this estimate most
- Video, screen sharing, and participant count all change the intensity of online work tools.
- Background browser and app activity can keep the system drawing power even outside meetings.
- Meeting-heavy workflows create both device-side and network-side overhead.
Assumptions and boundaries
- The estimate reflects active use rather than an app left open but unused.
- It is built to compare common digital work behaviors, not to audit a specific office setup.
- It includes both the device and the infrastructure supporting the session.
Uncertainty note: Work-tool emissions depend heavily on call quality, participant count, device efficiency, and how much multitasking happens during the session.
Yearly Impact Comparison
*IdleForest offsets ~200kg CO2/year on average per user.
Ways to reduce this footprint
- Turn video off when it is not necessary for the meeting outcome.
- Reduce meeting length and unnecessary participants when possible.
- Close heavy browser tabs and background tools during focused work.
Estimate review
Who reviewed this estimate
Reviewed by: IdleForest Research Team
Role: Editorial Review
Organization: IdleForest
Last reviewed: May 10, 2026
These estimates are meant to help compare digital habits. They are directional, not exact reproductions of proprietary vendor accounting.
Sources
Nature Communications: The environmental sustainability of digital content consumption
Peer-reviewed life-cycle assessment covering web use, social media, video, music streaming, and video conferencing.
IEA: Data centres and data transmission networks
Provides broader context on the infrastructure behind cloud and network energy use.
MIT CEEPR: How much can we reduce CO2 by planting trees?
Supports the offset conversion used by IdleForest: roughly 20kg CO2 absorbed per mature tree per year, with wide real-world variation.
More questions about Slack's carbon footprint
Is Slack a high-carbon app?
Slack is not as intensive as video streaming or gaming, but always-on work sessions, huddles, clips, and file previews give it a measurable footprint.
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About IdleForest
IdleForest is a desktop app that plants trees in the background while your computer is idle. It uses your unused internet bandwidth to fund reforestation projects.
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