ENVIRONMENTAL IMPACT
The environmental cost of email storage
Every email you keep sits on a server using a little power. Per message, the footprint is small. At the scale of billions of unused emails, it adds up — and unsubscribing from newsletters has an even bigger effect. Here's the honest math.
The hidden cost of a full inbox
The average office worker receives 120+ emails per day, and roughly half of all email sent worldwide is spam. Most of the rest is newsletters, promotions, and notifications nobody opens. Every one of them takes a small amount of space on a server — and every server runs 24/7 in a data center consuming electricity.
Data centers collectively use 1–2% of global electricity. Most of that demand is driven by AI, cloud computing, and video streaming. Email is a smaller contributor, but it's still part of the total — and unlike a movie you stream once, an email stays stored for years.
There's also the physical infrastructure: land cleared for data centers, water used for cooling, and fossil fuels burned to keep them running. Your forgotten emails have a small but real footprint in that system.
The numbers behind your inbox
Across the 4.3 million emails our users have deleted, the average message is about 50 KB. Its full carbon lifetime — writing, sending, routing, and years of storage combined — is around 0.3g CO₂. Most of that isn’t storage or transmission: it’s the electricity your device and the recipient’s burn during the minutes spent writing and reading it. Spam comes in around 0.03g precisely because nobody spends time on it.
Source: Berners-Lee, How Bad Are Bananas? 2nd ed., 2020; per-email size measured from Gmailytics cleanup data
This is our own estimate, not a published figure, and we’d rather show the work than cite it as fact: a modern high-capacity drive draws a few watts continuously, providers replicate your data across multiple data centers for reliability, and cooling plus networking add overhead on top. Modern hyperscale facilities are dramatically more efficient per unit of data than older estimates assumed — many figures still circulating online are far too high. Ours is deliberately a wide range, and the cost is ongoing for as long as the data exists.
Source: Gmailytics estimate; data center efficiency context from Masanet et al., Science, 2020
A single newsletter sends 1–4 emails per week. Over a year, that’s 50–200 emails you probably never open. Unsubscribing from 20 newsletters prevents 1,000–4,000 emails per year from being generated, transmitted, and stored — which is a bigger environmental win than deleting emails you already received.
A single hyperscale data center can cover 100,000+ sq ft and, depending on the cooling method, use several million gallons of water per day. Reducing stored data doesn’t shut down existing data centers, but it reduces the long-term pressure to build new ones.
Source: U.S. DOE, 2024
What cleaning your inbox actually does
The bigger environmental lever is unsubscribing — it prevents future emails from being sent, transmitted, and stored. Deleting old emails mainly saves ongoing storage. Both matter; they just work at different points in the life of an email.
The carbon savings from any one person cleaning their inbox are modest. The interesting scale comes from aggregation: if just 1% of Gmail's 1.8 billion users deleted 1,000 old emails each, that would free roughly 900 terabytes of storage and remove on the order of 20–70 tonnesof ongoing CO₂ per year from server load. Small per person — real at scale.
Less data stored = less pressure to build new data centers
Global data center capacity is growing rapidly, driven primarily by AI, cloud computing, and video streaming. Email storage is a much smaller share of that demand — but it's still part of the overall load, and efficiency improvements at the provider level only go so far.
Cleaning your inbox won't stop climate change, and we won't pretend it does. What it does is reduce waste — less wasted storage, less wasted attention, fewer marketing emails you never asked for. That's worth doing on its own, and the small environmental benefit is a genuine bonus.
What Gmailytics users have saved so far
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Sources
- Berners-Lee, M. (2020) — “How Bad Are Bananas? The Carbon Footprint of Everything”, 2nd ed. — email and digital footprint estimates
- The Radicati Group — Email Statistics Report — emails sent and received per business user per day
- Statista — share of global email traffic identified as spam
- Gmailytics internal cleanup data — average per-email size, measured across 4.3M deleted emails; storage energy per GB is our own estimate, not a published figure
- Masanet, E. et al. (2020) — “Recalibrating global data center energy-use estimates” — Science, 367(6481)
- U.S. Department of Energy (2024) — Data center energy and water usage reports
- Google Environmental Report (2024) — Data center efficiency and renewable energy usage
- International Energy Agency (2024) — “Data Centres and Data Transmission Networks”