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Comparison · 2 models · Updated Nov 2, 2026

Claude Opus 5.5 vs GPT-6.1 Sol

GPT-6.1 Sol comes out ahead, 72 to 69 on our weighted score, and it is the cheaper option too.

  1. Anthropic

    Claude Opus 5.5

    Released Sep 22, 2026New

    69/100
    • ECI168.4
    • Price$4.00 / $20.00
    • Context1M
    Full specs Remove Claude Opus 5.5
  2. Our pick

    OpenAI

    GPT-6.1 Sol

    Released Sep 29, 2026New

    72/100
    • ECI167.8
    • Price$2.00 / $10.00
    • Context1.05M
    Full specs Remove GPT-6.1 Sol

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-6.1 Sol is our pick

GPT-6.1 Sol is the better all-round choice, scoring 72/100 against Claude Opus 5.5 (69). It leads on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Opus 5.5Capabilities Index (ECI): Claude Opus 5.5 168.4 · GPT-6.1 Sol 167.8
  • Lowest priceGPT-6.1 SolGPT-6.1 Sol $4.00 · Claude Opus 5.5 $8.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-6.1 SolGPT-6.1 Sol 1,050,000 · Claude Opus 5.5 1,000,000 tokens
  • Widest inputsSame inputsClaude Opus 5.5: Text, Images, PDFs · GPT-6.1 Sol: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Opus 5.5GPT-6.1 Sol
CapabilityCapabilities Index (ECI)50%9999
Price25%720
Inputs & features15%8080
Context window10%6061
Overall100%69/10072/100
02 — Side by side

Every spec in one table

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

Claude Opus 5.5 vs GPT-6.1 Sol specifications side by side
SpecificationClaude Opus 5.5AnthropicGPT-6.1 SolOpenAI
Capability
Capabilities Index (ECI)168.4 (best)167.8
ECI rank#2 of 165 (best)#4 of 165
GPQA DiamondGraduate-level science questions90.6%95.4% (best)
FrontierMath Tiers 1–3Research-level mathematics91.2%93.7% (best)
OTIS Mock AIME 2024–2025Competition mathematics100%100%
SimpleQA VerifiedShort factual questions72.2%73.9% (best)
Price per million tokens
Input$4.00$2.00 (best)
Output$20.00$10.00 (best)
Cached input$0.20$0.10 (best)
Blended (3:1)$8.00$4.00 (best)
Long-context rateSame rateOver 272K: $4.00 / $15.00
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-opus-5-5gpt-6.1-sol
API providers36 (best)33
ReleasedSep 22, 2026Sep 29, 2026
Knowledge cutoffJun 2026Apr 30, 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 Opus 5.5$80.00
  • GPT-6.1 Sol$40.00
04 — Questions

Which should you choose?

Which is better: Claude Opus 5.5 or GPT-6.1 Sol?

GPT-6.1 Sol is the better all-round choice, scoring 72/100 against Claude Opus 5.5 (69). It leads on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Opus 5.5 or GPT-6.1 Sol?

GPT-6.1 Sol is cheaper at $2.00 input / $10.00 output per million tokens (official OpenAI API price). Claude Opus 5.5 costs $4.00 input / $20.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6.1 Sol versus $8.00 for Claude Opus 5.5 (2× as much).

Which scores higher on benchmarks?

Claude Opus 5.5 scores higher on the Capabilities Index (ECI): Claude Opus 5.5 168.4 (#2 of 165) and GPT-6.1 Sol 167.8 (#4 of 165). The confidence ranges of the top two overlap (165.4–173.0 vs 164.3–172.5), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-6.1 Sol 95.4%, Claude Opus 5.5 90.6%; FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, Claude Opus 5.5 91.2%; OTIS Mock AIME 2024–2025 — Claude Opus 5.5 100%, GPT-6.1 Sol 100%; SimpleQA Verified — GPT-6.1 Sol 73.9%, Claude Opus 5.5 72.2%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Opus 5.5 and GPT-6.1 Sol yet, so there is no like-for-like coding score. On overall capability, Claude Opus 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-6.1 Sol has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Opus 5.5. Maximum output per response: Claude Opus 5.5 up to 128,000, GPT-6.1 Sol up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Opus 5.5 accepts text, images and PDFs; GPT-6.1 Sol accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Opus 5.5 and GPT-6.1 Sol are proprietary and only available through APIs and apps.

Which is newer?

GPT-6.1 Sol is the newest, released Sep 29, 2026. Claude Opus 5.5 came out Sep 22, 2026. Knowledge cutoff: Claude Opus 5.5 Jun 2026, GPT-6.1 Sol Apr 30, 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 Nov 2, 2026.

05 — Keep comparing

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