Hi, I'm co-founder of Neuralwatt. While there aren't other providers selling by energy we also produce the same tokens stats you get at others (input, output, cached) and you can compare using those. The CO2 number is really just multiplying the energy by the CO2-intensity at the time/place we served the request. So everything is actually measured and can be derived externally.

The main observation when you compare to token prices our input/cached energy is much lower than the equivalent token prices while the output energy is generally higher. One of the reasons this is a bit cheaper, especially for agentic systems, is that in an fully built/cached session your input & cached to output ratio is really massive input to very small output (multiple orders of magnitude usually). The other thing we do is we actively work to optimize the system around tokens/joule with the goal of making the most energy-optimal system.

Happy to answer any other questions.