I spend most of my working day inside Claude Code. At some point I started wondering what that adds up to, physically. I just wanted a number next to the session cost, something to glance at rather than feel bad about. There is no official answer. Anthropic, like every frontier lab, does not publish per-inference energy data. So I built the estimate myself, put it in my status line, and open-sourced the whole thing as claude-carbon . This post is the methodology: where the numbers come...