A back-of-envelope CO₂e estimate for your site's data transfer. Runs entirely in your browser — nothing you type leaves this page.
This is an educational, order-of-magnitude estimate — not a carbon footprint audit, not suitable for compliance reporting, and not a substitute for hosting-provider or lifecycle assessments. It multiplies transferred gigabytes by a single rough factor (0.81 g CO₂e per GiB) sometimes used for "internet energy" back-of-envelope examples. It ignores, among other things:
Every page load moves bytes: HTML, CSS, JavaScript, fonts, and — usually the biggest share — images and video. Moving those bytes through data centers, network routers, and mobile towers takes electricity, and generating that electricity (depending on the grid) emits CO₂. So the chain is simple: page weight → data transferred → energy used → emissions. Each link in the chain is fuzzy, which is why any per-GiB factor is at best an order of magnitude — but the direction is reliable: lighter pages transfer less and emit less, and they're faster for your visitors too.
If you want real numbers instead of assumptions, Tracely measures actual transfer sizes from the browser's Navigation Timing API and shows this same sustainability estimate on your Overview dashboard automatically — computed from your real traffic, no extra setup. See the features page for details.