Side by side
Compare two AI models
Pick two models and see what each costs, how well it works and what it's actually for. The scores are my own judgment on a 1–5 scale from using these — not vendor claims and not benchmark results. Your picks stay in the address bar, so you can send the comparison to someone else.
Choose a second model above to see them side by side.
Frontier flagship models
Claude Opus 5.5
Anthropic
Visit- Published benchmark scores
- Artificial Analysis Intelligence Index v4.3.258 — 1st of 216 models
combined score across ten reasoning and knowledge tests · tested: max with fallback
Artificial Analysis · 28 September 2026 · independent
Measured at 95.2 tokens per second output speed.
Figures copied from the sources above, checked 17 September 2026.
- Cost
- API $4 in / $20 out per million tokens; Claude plans from free to $100/month.
- Performance
- Anthropic's model for long-running agentic coding and knowledge work, and the first release since the lab called for pacing the frontier. Its launch post reports it matches Claude Fable 5.1 on most work at 40% lower running cost than Opus 5; benchmark figures are the maker's own, so check independent leaderboards for a specific task.
- Use it for
- Long-running coding and migration tasks
- Knowledge-work and document reasoning
- Agentic workflows through Claude paid plans
- Keep in mind
- Heavier Opus 5.5 access needs a paid Claude plan; the free plan applies a rolling usage window.