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Claude Opus 4.8 vs GPT-5.5
Of the 5 public leaderboards that rate both, Claude Opus 4.8 scores higher on 3 and GPT-5.5 on 2. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Opus 4.8 is at 46.7 and GPT-5.5 at 44.8 (out of 100).
Scores as published by each board; table composed September 25, 2026.
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Leaderboard by leaderboard
| Board | Claude Opus 4.8 | GPT-5.5 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,555.2 | 1,510.1 | Claude Opus 4.8 |
| LiveBench global average (0-100) | 76.2 | 80.2 | GPT-5.5 |
| SimpleBench AVG@5 % (private set) | 64.8 | 76.9 | GPT-5.5 |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 60.9 | 57.4 | Claude Opus 4.8 |
| Artificial Analysis intelligence index · measured runs only | 41.8 | 38.4 | Claude Opus 4.8 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
Claude Opus 4.8 at a glance
- Developer
- Anthropic
- Status
- Live since May 27, 2026
- API price
- $5 input / $25 output per 1M tokens · Anthropic, claude-opus-4-8
- Context window
- 1M tokens
Live.
GPT-5.5 at a glance
- Developer
- OpenAI
- Status
- Live since April 24, 2026
- API price
- $5 input / $30 output per 1M tokens · OpenAI, gpt-5.5
- Context window
- 1.05M tokens
Live.
Claude Opus 4.8 vs GPT-5.5: quick answers
Which is better, Claude Opus 4.8 or GPT-5.5?
It depends on what you measure. Of the 5 public leaderboards that rate both, Claude Opus 4.8 scores higher on 3 and GPT-5.5 on 2. Claude Opus 4.8's widest lead is on Vals AI; GPT-5.5's widest lead is on SimpleBench. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Opus 4.8 is at 46.7 and GPT-5.5 at 44.8 (out of 100).
Which is newer, Claude Opus 4.8 or GPT-5.5?
Claude Opus 4.8. It went live on May 27, 2026, 33 days after GPT-5.5 (April 24, 2026).
Which is cheaper, Claude Opus 4.8 or GPT-5.5?
Claude Opus 4.8 is cheaper on output; input costs the same. On each vendor's own API, Claude Opus 4.8 is $5 input / $25 output per million tokens and GPT-5.5 is $5 input / $30 output per million tokens. GPT-5.5's rate rises for prompts over 272K tokens. Prices as published in the models.dev catalog, as of 2026-09-25.
Which has the bigger context window, Claude Opus 4.8 or GPT-5.5?
GPT-5.5, at 1.05M tokens against Claude Opus 4.8's 1M, as each vendor lists it.
Who makes Claude Opus 4.8 and GPT-5.5?
Claude Opus 4.8 is from Anthropic; GPT-5.5 is from OpenAI.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed September 25, 2026). Boards measure different things, so raw scores are only comparable within a row.
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Also: the bench index · API pricing · the wire