GPT-5.5 vs Claude Opus 4.8: Same Input Price, Very Different Output Bills

Both GPT-5.5 and Claude Opus 4.8 come in at $5.00/1M input tokens, so the pricing duel really comes down to output: OpenAI charges $30.00/1M out, while Anthropic sits at $25.00/1M out. That 17% gap adds up fast on long-form tasks.

In practice, GPT-5.5 feels slightly snappier on structured outputs and tool-calling chains — it rarely fumbles JSON schemas or loses track of multi-step function calls. Claude Opus 4.8 punches harder on nuanced reasoning and longer context retention. Ask it to synthesize a 40-page doc and it stays coherent where GPT-5.5 occasionally drifts or repeats itself near the end.

For coding, it's close. GPT-5.5 tends to produce cleaner boilerplate faster. Opus 4.8 is more likely to flag an edge case you hadn't considered — which is either helpful or annoying depending on your workflow.

Where Opus 4.8 wins clearly: instruction-following on complex, layered prompts. GPT-5.5 has a habit of slightly paraphrasing constraints rather than obeying them exactly.

Bottom line: if you're running high-output workloads, Opus 4.8's $5/1M output savings matter. If tight tool integration is your priority, GPT-5.5 earns its premium. Neither is a runaway winner.