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Comparison · 3 models · Updated Oct 4, 2026

Grok 4.5 vs Claude Sonnet 5 vs Gemini 3.5 Flash

Too close to call on our weighted score (Gemini 3.5 Flash 69, Claude Sonnet 5 66, Grok 4.5 64). The right pick depends on what you value most.

  1. xAI

    Grok 4.5

    Released Jul 8, 2026

    64/100
    • ECI154.0
    • Price$2.00 / $6.00
    • Context500K
    Full specs Remove Grok 4.5

  2. Anthropic

    Claude Sonnet 5

    Released Jun 30, 2026

    66/100
    • ECI156.3
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5

  3. Google

    Gemini 3.5 Flash

    Released May 19, 2026

    69/100
    • ECI154.5
    • Price$1.50 / $9.00
    • Context1.05M
    Full specs Remove Gemini 3.5 Flash
01 — Verdict

Too close to call

It is close. Our weighted score puts them within 3 points (Gemini 3.5 Flash 69/100, Claude Sonnet 5 66/100, Grok 4.5 64/100), so choose by what matters most for your work: Claude Sonnet 5 for raw capability, Grok 4.5 on price and Gemini 3.5 Flash for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 5Capabilities Index (ECI): Claude Sonnet 5 156.3 · Gemini 3.5 Flash 154.5 · Grok 4.5 154.0
  • Lowest priceGrok 4.5Grok 4.5 $3.00 · Gemini 3.5 Flash $3.38 · Claude Sonnet 5 $4.00 per 1M tokens (3:1 blend)
  • Longest contextGemini 3.5 FlashGemini 3.5 Flash 1,048,576 · Claude Sonnet 5 1,000,000 · Grok 4.5 500,000 tokens
  • Widest inputsGemini 3.5 FlashGrok 4.5: Text, Images · Claude Sonnet 5: Text, Images, PDFs · Gemini 3.5 Flash: Text, Images, PDFs, Audio, Video
  • Self-hostingNo open weightsAll three are available only through APIs
How the score is built
MeasureWeightGrok 4.5Claude Sonnet 5Gemini 3.5 Flash
CapabilityCapabilities Index (ECI)50%838684
Price25%272125
Inputs & features15%7080100
Context window10%486061
Overall100%64/10066/10069/100
02 — Side by side

Every spec in one table

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

Grok 4.5 vs Claude Sonnet 5 vs Gemini 3.5 Flash specifications side by side
SpecificationGrok 4.5xAIClaude Sonnet 5AnthropicGemini 3.5 FlashGoogle
Capability
Capabilities Index (ECI)154.0156.3 (best)154.5
ECI rank#36 of 148#23 of 148 (best)#33 of 148
GPQA DiamondGraduate-level science questions93.4% (best)90.5%92.8%
FrontierMath Tiers 1–3Research-level mathematics57.2%65.6% (best)62.8%
OTIS Mock AIME 2024–2025Competition mathematics97.8% (best)94.7%95.6%
SWE-bench VerifiedFixing real GitHub issues——79.3%
SimpleQA VerifiedShort factual questions48.3%33.7%66.2% (best)
Price per million tokens
Input$2.00$2.00$1.50 (best)
Output$6.00 (best)$10.00$9.00
Cached input$0.30$0.20$0.15 (best)
Blended (3:1)$3.00 (best)$4.00$3.38
Long-context rateOver 200K: $4.00 / $12.00Same rateSame rate
Price sourceOfficial xAI APIOfficial Anthropic APIOfficial Google API
Limits
Context window500,000 tokens1,000,000 tokens1,048,576 tokens (best)
Max output500,000 tokens (best)128,000 tokens65,536 tokens
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsNoYesYes
AudioNoNoYes
VideoNoNoYes
ReasoningYeslow · medium · highYeslow · medium · high · xhigh · maxYesminimal · low · medium · high
Tool callingYesYesYes
Structured outputYesYesYes
Availability
WeightsProprietaryProprietaryProprietary
API model IDgrok-4.5claude-sonnet-5gemini-3.5-flash
API providers2438 (best)32
ReleasedJul 8, 2026Jun 30, 2026May 19, 2026
Knowledge cutoff—Jan 31, 2026Jan 2025
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.

  • Grok 4.5$32.00
  • Claude Sonnet 5$40.00
  • Gemini 3.5 Flash$33.00
04 — Questions

Which should you choose?

Which is better: Grok 4.5, Claude Sonnet 5 or Gemini 3.5 Flash?

It is close. Our weighted score puts them within 3 points (Gemini 3.5 Flash 69/100, Claude Sonnet 5 66/100, Grok 4.5 64/100), so choose by what matters most for your work: Claude Sonnet 5 for raw capability, Grok 4.5 on price and Gemini 3.5 Flash for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Grok 4.5, Claude Sonnet 5 or Gemini 3.5 Flash?

Grok 4.5 is cheaper at $2.00 input / $6.00 output per million tokens (official xAI API price). Gemini 3.5 Flash costs $1.50 input / $9.00 output per million tokens (official Google API price); Claude Sonnet 5 costs $2.00 input / $10.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.00 per million tokens for Grok 4.5 versus $3.38 for Gemini 3.5 Flash (1.1× as much) and $4.00 for Claude Sonnet 5 (1.3× as much).

Which scores higher on benchmarks?

Claude Sonnet 5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5 156.3 (#23 of 148), Gemini 3.5 Flash 154.5 (#33 of 148) and Grok 4.5 154.0 (#36 of 148). The confidence ranges of the top two overlap (153.6–158.8 vs 152.5–156.6), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.5 93.4%, Gemini 3.5 Flash 92.8%, Claude Sonnet 5 90.5%; FrontierMath Tiers 1–3 — Claude Sonnet 5 65.6%, Gemini 3.5 Flash 62.8%, Grok 4.5 57.2%; OTIS Mock AIME 2024–2025 — Grok 4.5 97.8%, Gemini 3.5 Flash 95.6%, Claude Sonnet 5 94.7%; SimpleQA Verified — Gemini 3.5 Flash 66.2%, Grok 4.5 48.3%, Claude Sonnet 5 33.7%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.5 and Claude Sonnet 5 yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 5 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?

Gemini 3.5 Flash has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Sonnet 5 and 500,000 for Grok 4.5. Maximum output per response: Grok 4.5 up to 500,000, Claude Sonnet 5 up to 128,000, Gemini 3.5 Flash up to 65,536 tokens.

Which can read images, PDFs, audio or video?

Grok 4.5 accepts text and images; Claude Sonnet 5 accepts text, images and PDFs; Gemini 3.5 Flash accepts text, images, PDFs, audio and video. Gemini 3.5 Flash handles the widest range of inputs.

Are any of these open source?

No. Grok 4.5, Claude Sonnet 5 and Gemini 3.5 Flash are proprietary and only available through APIs and apps.

Which is newer?

Grok 4.5 is the newest, released Jul 8, 2026. Claude Sonnet 5 came out Jun 30, 2026; Gemini 3.5 Flash came out May 19, 2026. Knowledge cutoff: Claude Sonnet 5 Jan 31, 2026, Gemini 3.5 Flash Jan 2025.

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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