There is a modest compute overhead cost, I think on the order of 1%, and the costs of the increased security for the model weights. These seem modest.
The inference cost increase of the ASL-3 deployment classifiers is probably around 4%, though plausibly more like 10%. Based on the constitutional classifiers paper, the additional cost on top of 3.5 Sonnet was 20%. Opus 4 is presumably more expensive than 3.5 Sonnet, making the relative cost increase (assuming the same size of classifier model is used) smaller. How much smaller? If you assume inference cost is proportional to the API price, Opus 4 is 5x more expensive than Sonnet 3.5/4 making the relative increase 4%. I’d guess this is more likely to be overestimate of Opus 4′s relative cost based on recent trends in model size, so maybe Opus is only ~2x more expensive than Sonnet yielding a 10% increase in cost.
The inference cost increase of the ASL-3 deployment classifiers is probably around 4%, though plausibly more like 10%. Based on the constitutional classifiers paper, the additional cost on top of 3.5 Sonnet was 20%. Opus 4 is presumably more expensive than 3.5 Sonnet, making the relative cost increase (assuming the same size of classifier model is used) smaller. How much smaller? If you assume inference cost is proportional to the API price, Opus 4 is 5x more expensive than Sonnet 3.5/4 making the relative increase 4%. I’d guess this is more likely to be overestimate of Opus 4′s relative cost based on recent trends in model size, so maybe Opus is only ~2x more expensive than Sonnet yielding a 10% increase in cost.