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Claude Sonnet 5.5

Anthropic · Released Sep 28, 2026 · 27 days ago · Closed weights
Latest Claude Sonnet

Fast Claude model for everyday coding, agents, and knowledge work

Strongest at
Reasoning
Top 6% of the past year's models · 3 of 5 benchmarks
Price per 1M tokens
$2 / $10
input / output · Anthropic
Context window
1M
tokens in · 128K out
Since the last one
90 days
after Claude Sonnet 5
Lab announcement ↗Open in the timeline

Capability profile

Scored against 90 models released in the past year. 50 is the average model; further out is better.

This modelClaude Sonnet 5Median of the past year
50100Median of the past yearClaude Sonnet 5Coding: 71 · Top 8%Writing: 55 · Better than 45%Reading & documents: 67 · Top 14%Reasoning: 81 · Top 6%Math: 75 · Top 7%Science: 76 · Top 6%Visual reasoning: 71 · Top 13%Computer use: 92 · Top 8%CodingWritingReadingReasoningMathScienceVisionComputer use
Coding71+11.1Top 8%
Writing55−1.2Better than 45% · 1 test
Reading & documents67+15.6Top 14%
Reasoning81+17.2Top 6%
Math75+13.3Top 7%
Science76+9.9Top 6%
Visual reasoning71+25.9Top 13%
Computer use92+37.8Top 8%
Where these scores come from

Each capability combines the published benchmarks listed here, rescaled so 50 is the reference average and 15 points is one standard deviation. A hollow dot rests on a single benchmark.

Price against capability

The shaded corner holds anything better and cheaper. Prices blend input and output 3 to 1.

Nothing from the past year scores higher on Reasoning for less.

$0.1$0.3$1$3$10$3020406080DeepSeek V4.1 Flash 1017: 74, $0.26 per 1MClaude Haiku 5.5: 64, $0.2 per 1MMistral Large 4: 53, $2.06 per 1MGemini 4 Argon: 85, $4 per 1MGPT-6.1 Sol: 87, $4 per 1MGPT-6 Sol: 76, $4 per 1MGPT-6 Luna: 53, $0.2 per 1MClaude Opus 5.5: 84, $8 per 1MGrok 4.7: 60, $3 per 1MDeepSeek V4.1 Flash: 68, $0.27 per 1MGPT-6 Astra: 90, $20 per 1MMuse Spark 1.3: 60, $2 per 1MGemini 3.8 Flash: 75, $1.5 per 1MClaude Fable 5.1: 77, $20 per 1MGLM-5.3-Flash: 48, $0.24 per 1MDeepSeek V4 Flash Vision Exp: 54, $0.32 per 1MQwen3.8 27B: 49, $1.12 per 1MGLM-5.3: 60, $2.15 per 1MGemini 3.7 Flash: 73, $1.5 per 1MDeepSeek V4 Pro 0813: 66, $0.99 per 1MGrok 4.6: 66, $3 per 1MMuse Spark 1.2: 64, $2 per 1MQwen3.8 Max: 66, $3 per 1MDeepSeek V4 Flash 0731: 61, $0.067 per 1MClaude Opus 5: 76, $10 per 1MGemini 3.6 Flash: 61, $1.5 per 1MGemini 3.5 Flash Lite: 35, $0.85 per 1MKimi K3: 62, $6 per 1MQwen3.7 Flash: 42, $0.055 per 1MGPT-5.6 Terra: 66, $4.5 per 1MGPT-5.6 Sol: 76, $8 per 1MGPT-5.6 Luna: 57, $0.45 per 1MGrok 4.5: 63, $3 per 1MGLM-5.2: 49, $2.15 per 1MKimi K2.7 Code: 51, $1.71 per 1MClaude Fable 5: 74, $20 per 1MQwen3.7 Plus: 44, $0.7 per 1MClaude Opus 4.8: 68, $10 per 1MQwen3.7 Max: 58, $3.75 per 1MGemini 3.5 Flash: 64, $3.38 per 1MDeepSeek V4 Pro: 48, $0.26 per 1MDeepSeek V4 Flash: 21, $0.11 per 1MGPT-5.5 Pro: 79, $67.5 per 1MGPT-5.5: 75, $11.2 per 1MQwen3.6 27B: 27, $1.35 per 1MKimi K2.6: 46, $1.71 per 1MGrok 4.3: 22, $1.56 per 1MGrok Build 0.1: 34, $1.25 per 1MClaude Opus 4.7: 63, $10 per 1MQwen3.6 35B-A3B: 49, $0.84 per 1MMuse Spark 1.1: 61, $2 per 1MGLM-5.1: 54, $2.15 per 1MQwen3.6 Plus: 33, $1.12 per 1MGPT-5.4 nano: 48, $0.46 per 1MGPT-5.4 mini: 40, $1.69 per 1MGPT-5.4 Pro: 77, $67.5 per 1MGPT-5.4: 68, $5.62 per 1MQwen3.5 Flash: 47, $0.18 per 1MQwen3.5 122B-A10B: 44, $1.1 per 1MGemini 3.1 Pro Preview: 68, $4.5 per 1MClaude Sonnet 4.6: 54, $6 per 1MQwen3.5 Plus: 43, $0.9 per 1MQwen3.5 397B-A17B: 45, $1.35 per 1MGLM-5: 47, $1.55 per 1MClaude Opus 4.6: 55, $10 per 1MKimi K2.5: 46, $1 per 1MGLM-4.7: 51, $1 per 1MGemini 3 Flash Preview: 58, $1.12 per 1MGPT-5.2 Pro: 69, $57.8 per 1MGPT-5.2 Codex: 37, $4.81 per 1MGPT-5.2: 59, $4.81 per 1MClaude Opus 4.5: 61, $10 per 1MGPT-5.1: 54, $3.44 per 1MClaude Sonnet 5: 64, $4 per 1MClaude Sonnet 5.5: 81, $4 per 1MClaude Sonnet 5.5Price per 1M tokens →↑ Reasoning$0.1$1$1020406080DeepSeek V4.1 Flash 1017: 74, $0.26 per 1MClaude Haiku 5.5: 64, $0.2 per 1MMistral Large 4: 53, $2.06 per 1MGemini 4 Argon: 85, $4 per 1MGPT-6.1 Sol: 87, $4 per 1MGPT-6 Sol: 76, $4 per 1MGPT-6 Luna: 53, $0.2 per 1MClaude Opus 5.5: 84, $8 per 1MGrok 4.7: 60, $3 per 1MDeepSeek V4.1 Flash: 68, $0.27 per 1MGPT-6 Astra: 90, $20 per 1MMuse Spark 1.3: 60, $2 per 1MGemini 3.8 Flash: 75, $1.5 per 1MClaude Fable 5.1: 77, $20 per 1MGLM-5.3-Flash: 48, $0.24 per 1MDeepSeek V4 Flash Vision Exp: 54, $0.32 per 1MQwen3.8 27B: 49, $1.12 per 1MGLM-5.3: 60, $2.15 per 1MGemini 3.7 Flash: 73, $1.5 per 1MDeepSeek V4 Pro 0813: 66, $0.99 per 1MGrok 4.6: 66, $3 per 1MMuse Spark 1.2: 64, $2 per 1MQwen3.8 Max: 66, $3 per 1MDeepSeek V4 Flash 0731: 61, $0.067 per 1MClaude Opus 5: 76, $10 per 1MGemini 3.6 Flash: 61, $1.5 per 1MGemini 3.5 Flash Lite: 35, $0.85 per 1MKimi K3: 62, $6 per 1MQwen3.7 Flash: 42, $0.055 per 1MGPT-5.6 Terra: 66, $4.5 per 1MGPT-5.6 Sol: 76, $8 per 1MGPT-5.6 Luna: 57, $0.45 per 1MGrok 4.5: 63, $3 per 1MGLM-5.2: 49, $2.15 per 1MKimi K2.7 Code: 51, $1.71 per 1MClaude Fable 5: 74, $20 per 1MQwen3.7 Plus: 44, $0.7 per 1MClaude Opus 4.8: 68, $10 per 1MQwen3.7 Max: 58, $3.75 per 1MGemini 3.5 Flash: 64, $3.38 per 1MDeepSeek V4 Pro: 48, $0.26 per 1MDeepSeek V4 Flash: 21, $0.11 per 1MGPT-5.5 Pro: 79, $67.5 per 1MGPT-5.5: 75, $11.2 per 1MQwen3.6 27B: 27, $1.35 per 1MKimi K2.6: 46, $1.71 per 1MGrok 4.3: 22, $1.56 per 1MGrok Build 0.1: 34, $1.25 per 1MClaude Opus 4.7: 63, $10 per 1MQwen3.6 35B-A3B: 49, $0.84 per 1MMuse Spark 1.1: 61, $2 per 1MGLM-5.1: 54, $2.15 per 1MQwen3.6 Plus: 33, $1.12 per 1MGPT-5.4 nano: 48, $0.46 per 1MGPT-5.4 mini: 40, $1.69 per 1MGPT-5.4 Pro: 77, $67.5 per 1MGPT-5.4: 68, $5.62 per 1MQwen3.5 Flash: 47, $0.18 per 1MQwen3.5 122B-A10B: 44, $1.1 per 1MGemini 3.1 Pro Preview: 68, $4.5 per 1MClaude Sonnet 4.6: 54, $6 per 1MQwen3.5 Plus: 43, $0.9 per 1MQwen3.5 397B-A17B: 45, $1.35 per 1MGLM-5: 47, $1.55 per 1MClaude Opus 4.6: 55, $10 per 1MKimi K2.5: 46, $1 per 1MGLM-4.7: 51, $1 per 1MGemini 3 Flash Preview: 58, $1.12 per 1MGPT-5.2 Pro: 69, $57.8 per 1MGPT-5.2 Codex: 37, $4.81 per 1MGPT-5.2: 59, $4.81 per 1MClaude Opus 4.5: 61, $10 per 1MGPT-5.1: 54, $3.44 per 1MClaude Sonnet 5: 64, $4 per 1MClaude Sonnet 5.5: 81, $4 per 1MClaude Sonnet 5.5Price per 1M tokens →↑ Reasoning

Anthropic $2 / $10 · OpenRouter $2 / $10 · Cached input $0.1

Since Claude Sonnet 5

6 releases in the Claude Sonnet line.

Claude Sonnet 3.7Feb 19, 202592dClaude Sonnet 4May 22, 2025130dClaude Sonnet 4.5Sep 29, 2025141dClaude Sonnet 4.6Feb 17, 2026133dClaude Sonnet 5Jun 30, 202690dClaude Sonnet 5.5Sep 28, 2026
Released90 days later
Price in / out$2 / $10same price
Context1Msame
Coding71+11.1
Writing55−1.2
Reading & documents67+15.6
Reasoning81+17.2
Math75+13.3
Science76+9.9
Visual reasoning71+25.9
Computer use92+37.8
ECI STANDING#6 of 270
SCORE166.18163.06–171.34 CI
FRONTIER LAGLaunched 0.9 months behindScores about what Claude Fable 5.1 did in September 2026.
SCORES LIKE THESE MODELSGPT-6.1 SolOpenAI · Sep 2026168.37Claude Fable 5.1Anthropic · Sep 2026166.49Gemini 4 ArgonGoogle DeepMind · Sep 2026166.45Claude Opus 5Anthropic · Jul 2026163.94
Full Epoch Capabilities Index ranking ↗

Epoch benchmark boards

Best result on each board it has run. The tick marks the leader.

GPQA diamond
96%#3 of 233
OTIS Mock AIME 2024-2025
100%#3 of 215
ProofBench
100%#3 of 81
APEX-Agents
76%#2 of 51
Mystery Game Puzzles
65%#4 of 87
DTBench
97%#9 of 179
FrontierMath-Tiers-1-3-v2-Private
89%#7 of 89
FrontierCode
52%#5 of 46
7 more boards
FrontierMath-Tier-4-v2-Private
80%#8 of 71
Furniture Assembly
75%#4 of 34
Chess Puzzles
59%#13 of 93
FrontierSWE
62%#3 of 21
WeirdML v3
37%#6 of 23
SimpleQA Verified
46%#36 of 84
SpireClimb
1%#6 of 7

Anthropic's past year

12 release days in the past year, about one every 30 days. The next is expected around Nov 17, 2026. Forecasts ↗

NovDecJanFebMarAprMayJunJulAugSepOctNov

Specifications

RELEASE DATESep 28, 2026
WEIGHTSClosed weights
CONTEXT WINDOW1M
MAX OUTPUT128K
REASONINGNot listed
TOOL CALLINGNot listed
INPUTStext, image/jpeg, image/png, image/gif, image/webp, application/pdf
OUTPUTStext

Models.dev record ↗

Specifications and prices from Models.dev; availability and limits may differ by provider. Benchmarks from Epoch AI (CC BY 4.0), LiveBench and the other sources named above.