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Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 5.5 vs GPT-5.6 Sol

Claude Sonnet 5.5 comes out ahead, 72 to 66 on our weighted score, and it is the cheaper option too.

  1. Our pick

    Anthropic

    Claude Sonnet 5.5

    Released Sep 28, 2026

    72/100
    • ECI165.2
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5.5

  2. OpenAI

    GPT-5.6 Sol

    Released Jul 9, 2026

    66/100
    • ECI161.8
    • Price$4.00 / $20.00
    • Context1.05M
    Full specs Remove GPT-5.6 Sol

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Claude Sonnet 5.5 is our pick

Claude Sonnet 5.5 is the better all-round choice, scoring 72/100 against GPT-5.6 Sol (66). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 5.5Capabilities Index (ECI): Claude Sonnet 5.5 165.2 · GPT-5.6 Sol 161.8
  • Lowest priceClaude Sonnet 5.5Claude Sonnet 5.5 $4.00 · GPT-5.6 Sol $8.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.6 SolGPT-5.6 Sol 1,050,000 · Claude Sonnet 5.5 1,000,000 tokens
  • Widest inputsSame inputsClaude Sonnet 5.5: Text, Images, PDFs · GPT-5.6 Sol: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Sonnet 5.5GPT-5.6 Sol
CapabilityCapabilities Index (ECI)50%9793
Price25%217
Inputs & features15%8080
Context window10%6061
Overall100%72/10066/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Claude Sonnet 5.5 vs GPT-5.6 Sol specifications side by side
SpecificationClaude Sonnet 5.5AnthropicGPT-5.6 SolOpenAI
Capability
Capabilities Index (ECI)165.2 (best)161.8
ECI rank#3 of 148 (best)#8 of 148
GPQA DiamondGraduate-level science questions95.6% (best)93.5%
FrontierMath Tiers 1–3Research-level mathematics88.8%89.1% (best)
OTIS Mock AIME 2024–2025Competition mathematics100%100%
SimpleQA VerifiedShort factual questions46.5%69.7% (best)
Price per million tokens
Input$2.00 (best)$4.00
Output$10.00 (best)$20.00
Cached input$0.20 (best)$0.40
Blended (3:1)$4.00 (best)$8.00
Long-context rateSame rateOver 272K: $8.00 / $30.00
Price sourceOfficial Anthropic APIOfficial OpenAI API
Limits
Context window1,000,000 tokens1,050,000 tokens (best)
Max output128,000 tokens128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhigh · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDclaude-sonnet-5-5gpt-5.6-sol
API providers2340 (best)
ReleasedSep 28, 2026Jul 9, 2026
Knowledge cutoffJun 2026Feb 16, 2026
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Claude Sonnet 5.5$40.00
  • GPT-5.6 Sol$80.00
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 5.5 or GPT-5.6 Sol?

Claude Sonnet 5.5 is the better all-round choice, scoring 72/100 against GPT-5.6 Sol (66). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 5.5 or GPT-5.6 Sol?

Claude Sonnet 5.5 is cheaper at $2.00 input / $10.00 output per million tokens (official Anthropic API price). GPT-5.6 Sol costs $4.00 input / $20.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for Claude Sonnet 5.5 versus $8.00 for GPT-5.6 Sol (2× as much).

Which scores higher on benchmarks?

Claude Sonnet 5.5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5.5 165.2 (#3 of 148) and GPT-5.6 Sol 161.8 (#8 of 148). The confidence ranges of the top two overlap (161.8–169.4 vs 159.3–165.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, GPT-5.6 Sol 93.5%; FrontierMath Tiers 1–3 — GPT-5.6 Sol 89.1%, Claude Sonnet 5.5 88.8%; OTIS Mock AIME 2024–2025 — Claude Sonnet 5.5 100%, GPT-5.6 Sol 100%; SimpleQA Verified — GPT-5.6 Sol 69.7%, Claude Sonnet 5.5 46.5%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Sonnet 5.5 and GPT-5.6 Sol yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 5.5 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.6 Sol has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Sonnet 5.5. Maximum output per response: Claude Sonnet 5.5 up to 128,000, GPT-5.6 Sol up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 5.5 accepts text, images and PDFs; GPT-5.6 Sol accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Sonnet 5.5 and GPT-5.6 Sol are proprietary and only available through APIs and apps.

Which is newer?

Claude Sonnet 5.5 is the newest, released Sep 28, 2026. GPT-5.6 Sol came out Jul 9, 2026. Knowledge cutoff: Claude Sonnet 5.5 Jun 2026, GPT-5.6 Sol Feb 16, 2026.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

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