Estimating the Parameter Counts of the Claude 5 and GPT-5.6 Families
Parameter counts have been secret since GPT-4. With revised IKP probes we measured six GPT-5.6 variants and three Claude 5 models: sol sits near 2T with fable/opus and kimi-k3; terra and luna are indistinguishable; pro adds no capacity; honest models are hardest to measure.