← comparisons · head to head
Claude Opus 5.5 vs Claude Opus 4.8
Claude Opus 5.5 scores higher than Claude Opus 4.8 on all 3 public leaderboards that rate both. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Opus 5.5 is at 92.9 and Claude Opus 4.8 at 30.6 (out of 100). On each maker's API, Claude Opus 5.5 costs $4 / $20 per 1M tokens (input / output) and Claude Opus 4.8 $5 / $25.
Scores as published by each board; table composed November 10, 2026.
Get the next launch alert, free →
Leaderboard by leaderboard
| Board | Claude Opus 5.5 | Claude Opus 4.8 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,817.7 | 1,555.4 | Claude Opus 5.5 |
| SimpleBench AVG@5 % (private set) | 88.4 | 64.8 | Claude Opus 5.5 |
| Epoch AI Epoch Capabilities Index (ECI) · many benchmarks on one scale | 168.7 | 159.9 | Claude Opus 5.5 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Claude Opus 5.5 is at 89.8 (#3 of 47) and Claude Opus 4.8 at 52.4 (#19). Claude Opus 5.5 scores higher on both coding boards that rate them.
| Coding board | Claude Opus 5.5 | Claude Opus 4.8 |
|---|---|---|
| LMArena · Coding | 1,542.2 | 1,490.7 |
| Vals Vibe Code Bench | 90.3 | 82.7 |
Claude Opus 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since September 22, 2026
- API price
- $4 input / $20 output per 1M tokens · Anthropic, claude-opus-5-5
- Context window
- 1M tokens
Live — Sep 22 · $4/$20 per MTok, down from Opus 5 at $5/$25 · 1M ctx / 128K out · adaptive thinking always on, default effort medium · cache reads 5% of base input · Anthropic now says start here for most workloads, and Opus 5 is legacy · fast mode (speed: 'fast', up to 2.5x the output tokens per second by Anthropic's figure) at $8 / $40 per MTok, double standard, left research preview Oct 15 with no waitlist, access request or beta header; on the Claude API and on Claude in Microsoft Foundry (Azure-hosted), not on Bedrock, Google Cloud, Claude Platform on AWS, the Batch API or Priority Tier; @ClaudeDevs says Google Cloud is coming soon (Anthropic's fast mode docs, read Oct 16).
AI models go live a median of 4 months after their knowledge ends: Claude Opus 5.5 knows up to June 2026, Gemini 4 Argon only to March
2026-11-06 · Of the 22 live AI models whose labs publish a knowledge cutoff, the median went live 4 months after its training data ends, by ArtificialWatch's count. The latest published cutoff we found is June 2026, for Anthropic's four current Claude models and OpenAI's GPT-6.1 Terra.
SemiAnalysis launches GDPx: Opus 5.5 leads at 12%, Gemini 4 Carbon close behind
2026-11-02 · SemiAnalysis released GDPx on November 2, a new agentic benchmark of 206 tasks across 11 domains, and the best model it tested scores 12%. Claude Opus 5.5 leads at 12.0, Gemini 4 Carbon is second at 10.9 and GPT-6 Astra third at 9.6. We read the leaderboard directly at gdpx.semianalysis.com.
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.
Claude Opus 5.5 vs Claude Opus 4.8: quick answers
Which is better, Claude Opus 5.5 or Claude Opus 4.8?
It depends on what you measure. Claude Opus 5.5 scores higher than Claude Opus 4.8 on all 3 public leaderboards that rate both. Claude Opus 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 5.5 is at 92.9 and Claude Opus 4.8 at 30.6 (out of 100).
Which is newer, Claude Opus 5.5 or Claude Opus 4.8?
Claude Opus 5.5. It went live on September 22, 2026, 118 days after Claude Opus 4.8 (May 27, 2026).
Which is cheaper, Claude Opus 5.5 or Claude Opus 4.8?
Claude Opus 5.5 is cheaper on both input and output. On each vendor's own API, Claude Opus 5.5 is $4 input / $20 output per million tokens and Claude Opus 4.8 is $5 input / $25 output per million tokens. Prices as published in the models.dev catalog, as of 2026-11-11.
Which has the bigger context window, Claude Opus 5.5 or Claude Opus 4.8?
Neither. Both take 1M tokens.
How do Claude Opus 5.5 and Claude Opus 4.8 compare for coding?
On the ArtificialWatch coding index, Claude Opus 5.5 is at 89.8 (#3 of 47) and Claude Opus 4.8 at 52.4 (#19). Claude Opus 5.5 scores higher on both coding boards that rate them.
Who makes Claude Opus 5.5 and Claude Opus 4.8?
Both are from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed November 10, 2026). Boards measure different things, so raw scores are only comparable within a row.
More comparisons
Hear when the next one drops. Free.
Free: a Chrome push and an email about 15 minutes after a new model answers on a public API. Members get a text or a phone call the moment a launch is confirmed.
- Free forever
- No card
- Unsubscribe in one click
Also: the bench index · API pricing · what a workload costs on each · the wire