ZMIME
Comparison · 3 models · Updated Oct 4, 2026

GPT-6 Sol vs Gemini 3.1 Pro Preview vs Claude Sonnet 5.5

Too close to call on our weighted score (GPT-6 Sol 67, Gemini 3.1 Pro Preview 66, Claude Sonnet 5.5 65). The right pick depends on what you value most.

  1. OpenAI

    GPT-6 Sol

    Released Sep 22, 2026

    67/100
    • ECI—
    • Price$2.00 / $10.00
    • Context1.05M
    Full specs Remove GPT-6 Sol

  2. Google

    Gemini 3.1 Pro Preview

    Released Feb 19, 2026

    66/100
    • ECI154.8
    • Price$2.00 / $12.00
    • Context1.05M
    Full specs Remove Gemini 3.1 Pro Preview

  3. Anthropic

    Claude Sonnet 5.5

    Released Sep 28, 2026

    65/100
    • ECI165.2
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5.5
01 — Verdict

Too close to call

It is close. Our weighted score puts them within a point (GPT-6 Sol 67/100, Gemini 3.1 Pro Preview 66/100, Claude Sonnet 5.5 65/100), so choose by what matters most for your work: GPT-6 Sol for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Sol has no Capabilities Index score yet.

  • CapabilityGPT-6 SolShared benchmarks: GPT-6 Sol 86.2% · Claude Sonnet 5.5 82.7% · Gemini 3.1 Pro Preview 80.8%
  • Lowest priceGPT-6 Sol and Claude Sonnet 5.5GPT-6 Sol $4.00 · Claude Sonnet 5.5 $4.00 · Gemini 3.1 Pro Preview $4.50 per 1M tokens (3:1 blend)
  • Longest contextGPT-6 Sol and Gemini 3.1 Pro PreviewGPT-6 Sol 1,050,000 · Gemini 3.1 Pro Preview 1,048,576 · Claude Sonnet 5.5 1,000,000 tokens
  • Widest inputsGemini 3.1 Pro PreviewGPT-6 Sol: Text, Images, PDFs · Gemini 3.1 Pro Preview: Text, Images, PDFs, Audio, Video · Claude Sonnet 5.5: Text, Images, PDFs
  • Self-hostingNo open weightsAll three are available only through APIs
How the score is built
MeasureWeightGPT-6 SolGemini 3.1 Pro PreviewClaude Sonnet 5.5
CapabilityShared benchmarks50%868183
Price25%211921
Inputs & features15%8010080
Context window10%616160
Overall100%67/10066/10065/100
02 — Side by side

Every spec in one table

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

GPT-6 Sol vs Gemini 3.1 Pro Preview vs Claude Sonnet 5.5 specifications side by side
SpecificationGPT-6 SolOpenAIGemini 3.1 Pro PreviewGoogleClaude Sonnet 5.5Anthropic
Capability
Capabilities Index (ECI)—154.8165.2 (best)
ECI rank—#31 of 148#3 of 148 (best)
GPQA DiamondGraduate-level science questions94.3%94.4%95.6% (best)
FrontierMath Tiers 1–3Research-level mathematics89.8% (best)59.7%88.8%
OTIS Mock AIME 2024–2025Competition mathematics100% (best)95.6%100% (best)
SWE-bench VerifiedFixing real GitHub issues—75.6%—
SimpleQA VerifiedShort factual questions60.7%73.5% (best)46.5%
Price per million tokens
Input$2.00$2.00$2.00
Output$10.00 (best)$12.00$10.00 (best)
Cached input$0.20$0.20$0.20
Blended (3:1)$4.00 (best)$4.50$4.00 (best)
Long-context rateOver 272K: $4.00 / $15.00Over 200K: $4.00 / $18.00Same rate
Price sourceOfficial OpenAI APIOfficial Google APIOfficial Anthropic API
Limits
Context window1,050,000 tokens (best)1,048,576 tokens1,000,000 tokens
Max output128,000 tokens (best)65,536 tokens128,000 tokens (best)
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsYesYesYes
AudioNoYesNo
VideoNoYesNo
ReasoningYeslow · medium · high · xhigh · maxYeslow · medium · highYeslow · medium · high · xhigh · max
Tool callingYesYesYes
Structured outputYesYesYes
Availability
WeightsProprietaryProprietaryProprietary
API model IDgpt-6-solgemini-3.1-pro-previewclaude-sonnet-5-5
API providers2526 (best)23
ReleasedSep 22, 2026Feb 19, 2026Sep 28, 2026
Knowledge cutoffApr 20, 2026Jan 2025Jun 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.

  • GPT-6 Sol$40.00
  • Gemini 3.1 Pro Preview$44.00
  • Claude Sonnet 5.5$40.00
04 — Questions

Which should you choose?

Which is better: GPT-6 Sol, Gemini 3.1 Pro Preview or Claude Sonnet 5.5?

It is close. Our weighted score puts them within a point (GPT-6 Sol 67/100, Gemini 3.1 Pro Preview 66/100, Claude Sonnet 5.5 65/100), so choose by what matters most for your work: GPT-6 Sol for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Sol has no Capabilities Index score yet.

Which is cheaper, GPT-6 Sol, Gemini 3.1 Pro Preview or Claude Sonnet 5.5?

GPT-6 Sol is cheaper at $2.00 input / $10.00 output per million tokens (official OpenAI API price). Claude Sonnet 5.5 costs $2.00 input / $10.00 output per million tokens (official Anthropic API price); Gemini 3.1 Pro Preview costs $2.00 input / $12.00 output per million tokens (official Google API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6 Sol versus $4.00 for Claude Sonnet 5.5 (1× as much) and $4.50 for Gemini 3.1 Pro Preview (1.1× as much).

Which scores higher on benchmarks?

Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6 Sol 86.2%, Claude Sonnet 5.5 82.7% and Gemini 3.1 Pro Preview 80.8%. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, Gemini 3.1 Pro Preview 94.4%, GPT-6 Sol 94.3%; FrontierMath Tiers 1–3 — GPT-6 Sol 89.8%, Claude Sonnet 5.5 88.8%, Gemini 3.1 Pro Preview 59.7%; OTIS Mock AIME 2024–2025 — GPT-6 Sol 100%, Claude Sonnet 5.5 100%, Gemini 3.1 Pro Preview 95.6%; SimpleQA Verified — Gemini 3.1 Pro Preview 73.5%, GPT-6 Sol 60.7%, Claude Sonnet 5.5 46.5%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-6 Sol and Claude Sonnet 5.5 yet, so there is no like-for-like coding score. On overall capability, GPT-6 Sol leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.

Which has the bigger context window?

GPT-6 Sol and Gemini 3.1 Pro Preview have the largest context windows (1,050,000 and 1,048,576 tokens), against 1,000,000 for Claude Sonnet 5.5. Maximum output per response: GPT-6 Sol up to 128,000, Gemini 3.1 Pro Preview up to 65,536, Claude Sonnet 5.5 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

GPT-6 Sol accepts text, images and PDFs; Gemini 3.1 Pro Preview accepts text, images, PDFs, audio and video; Claude Sonnet 5.5 accepts text, images and PDFs. Gemini 3.1 Pro Preview handles the widest range of inputs.

Are any of these open source?

No. GPT-6 Sol, Gemini 3.1 Pro Preview and Claude Sonnet 5.5 are proprietary and only available through APIs and apps.

Which is newer?

Claude Sonnet 5.5 is the newest, released Sep 28, 2026. GPT-6 Sol came out Sep 22, 2026; Gemini 3.1 Pro Preview came out Feb 19, 2026. Knowledge cutoff: GPT-6 Sol Apr 20, 2026, Gemini 3.1 Pro Preview Jan 2025, Claude Sonnet 5.5 Jun 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

Related comparisons