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Claude Haiku 5.5 vs Claude Sonnet 5.5
Claude Sonnet 5.5 scores higher than Claude Haiku 5.5 on all 4 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 Haiku 5.5 is at 50.2 and Claude Sonnet 5.5 at 90.3 (out of 100).
Scores as published by each board; table composed October 8, 2026.
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Leaderboard by leaderboard
| Board | Claude Haiku 5.5 | Claude Sonnet 5.5 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,586.9 | 1,774.3 | Claude Sonnet 5.5 |
| LiveBench global average (0-100) | 72.1 | 77.8 | Claude Sonnet 5.5 |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 54.3 | 67 | Claude Sonnet 5.5 |
| Artificial Analysis intelligence index · measured runs only | 43.4 | 56 | Claude Sonnet 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 Haiku 5.5 is at 73.5 (#11 of 35) and Claude Sonnet 5.5 at 88.2 (#3). Claude Sonnet 5.5 scores higher on all 2 coding boards that rate both.
| Coding board | Claude Haiku 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| LiveBench · Coding | 67.5 | 73.8 |
| Vals Vibe Code Bench | 90.4 | 92.4 |
Claude Haiku 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since October 7, 2026
- API price
- $0.10 input / $0.50 output per 1M tokens · Anthropic, claude-haiku-5-5
- Context window
- 1M tokens
Live — Oct 7 · $0.10/$0.50 per MTok for prompts up to 100K tokens, $0.50/$2.50 above · cache reads $0.01 / $0.05 · 1M ctx / 128K out · knowledge cutoff Jun 2026 · in the API, the Claude apps, AWS, Google Cloud and Microsoft Foundry the same day · Anthropic's own table: OSWorld 2.1 72.4% (GPT-6 Luna 48.9%, Haiku 4.5 15.7%), Terminal-Bench 4.0 39.2% (Luna 16.4%) · Artificial Analysis Intelligence Index 43 at max effort, #2 of 179 in its price tier (read Oct 7) · our sweep fired on claude-haiku-5-5 at 17:52 UTC, OpenRouter listed it at 18:31.
Claude Haiku 5.5 is out at $0.10 / $0.50, a tenth of Haiku 4.5's price
2026-10-07 · Anthropic released Claude Haiku 5.5 on October 7 as claude-haiku-5-5, on the Claude API, Amazon Bedrock, Google Cloud, Microsoft Foundry and in the Claude apps.
Claude Sonnet 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since September 28, 2026
- API price
- $2 input / $10 output per 1M tokens · Anthropic, claude-sonnet-5-5
- Context window
- 1M tokens
Live — Sep 28 · $2/$10 per MTok, the same as Sonnet 5 · cache reads $0.20 at launch, halved to $0.10 on Oct 7, writes $2.50 · in the API, the Claude apps, AWS, Google Cloud and Azure the same day · 1M ctx / 128K out · knowledge cutoff Jun 2026 · Artificial Analysis Intelligence Index 56 at max effort, #3 of 216 reasoning models (read Sep 28) · Anthropic's own table: Terminal-Bench 4.0 70.6% (Opus 5.5 66.4%), OSWorld 2.1 80.1% (Opus 5.5 81.8%) · our sweep caught claude-sonnet-5-5 at 17:54 UTC and fired at 17:55.
Claude Sonnet 5.5 ships at Sonnet 5's price, and the first independent number puts it #3 among reasoning models
2026-09-28 · Claude Sonnet 5.5 is live. Our sweep read the id claude-sonnet-5-5 at 17:54:45 UTC on September 28 and the alert went out at 17:55:45, 60 seconds later, to 314 inboxes and one phone. OpenRouter listed it nine minutes after that.
Claude Sonnet 5.5: named by Anthropic, reportedly in partner testing, priced 89% by Sep 30
2026-09-27 · Anthropic has named Claude Sonnet 5.5 but has not dated it. Everything past the name is reported, not confirmed - and the one number that moves every day says it is close.
Claude Haiku 5.5 vs Claude Sonnet 5.5: quick answers
Which is better, Claude Haiku 5.5 or Claude Sonnet 5.5?
It depends on what you measure. Claude Sonnet 5.5 scores higher than Claude Haiku 5.5 on all 4 public leaderboards that rate both. Claude Sonnet 5.5's widest lead is on Vals AI. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Claude Haiku 5.5 is at 50.2 and Claude Sonnet 5.5 at 90.3 (out of 100).
Which is newer, Claude Haiku 5.5 or Claude Sonnet 5.5?
Claude Haiku 5.5. It went live on October 7, 2026, 9 days after Claude Sonnet 5.5 (September 28, 2026).
Which is cheaper, Claude Haiku 5.5 or Claude Sonnet 5.5?
Claude Haiku 5.5 is cheaper on both input and output. On each vendor's own API, Claude Haiku 5.5 is $0.10 input / $0.50 output per million tokens and Claude Sonnet 5.5 is $2 input / $10 output per million tokens. Claude Haiku 5.5's rate rises for prompts over 100K tokens. Prices as published in the models.dev catalog, as of 2026-10-08.
Which has the bigger context window, Claude Haiku 5.5 or Claude Sonnet 5.5?
Neither. Both take 1M tokens.
How do Claude Haiku 5.5 and Claude Sonnet 5.5 compare for coding?
On the ArtificialWatch coding index, Claude Haiku 5.5 is at 73.5 (#11 of 35) and Claude Sonnet 5.5 at 88.2 (#3). Claude Sonnet 5.5 scores higher on all 2 coding boards that rate both.
Who makes Claude Haiku 5.5 and Claude Sonnet 5.5?
Both are from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed October 8, 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