Does email really create carbon?
Email is invisible, but every message is stored and delivered using energy. Emails kept in cloud services such as Gmail, Outlook or Naver Mail sit on data center servers that draw power around the clock. One email uses very little energy, but tens of thousands add up.
Sending a plain text email is estimated at about 4 g CO₂ (Mike Berners-Lee). Attachments add upload, transfer and processing, which raises the figure considerably. Sending 20 emails a day comes to roughly 29 kg CO₂ a year, similar to driving about 120 km.
Newsletters and marketing emails are mostly deleted unread or ignored, yet receiving and processing them still uses energy. A single unsubscribe removes the emissions from every future email for the next 365 days.
How to use the calculator
Move the sliders to match your current habits and the yearly CO₂ updates in real time. Rough numbers are fine. This tool is meant for comparing the share of each item and finding what to clean up first, not for precise measurement.
In the savings simulator, adjust the share of old emails deleted and newsletters unsubscribed to see the expected saving update instantly. Compare which action makes the biggest difference.
Frequently asked questions
- Does deleting emails really reduce carbon?
- Deleting a stored email removes it from server storage. Gmail and similar services keep deleted mail in the trash for 30 days, so empty the trash to remove it completely. The saving from one email is tiny, but clearing 10,000 or more makes a noticeable difference.
- Why is unsubscribing from newsletters effective?
- One unsubscribe stops every future delivery. If you get 10 newsletters a day, that is 3,650 a year, and unsubscribing from 70% of them removes 2,555 deliveries. For one person that is only about 0.28 kg CO₂ a year, but if everyone does it the load on mail servers drops meaningfully.
- Is the data I enter stored?
- All calculations run in your browser. Nothing is sent to a server or saved, and the sliders reset when you reload the page.
