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Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 4.5 vs Grok 4.3

Grok 4.3 comes out ahead, 67 to 55 on our weighted score, and it is the cheaper option too.

  1. Anthropic

    Claude Sonnet 4.5

    Released Sep 29, 2025

    55/100
    • ECI146.8
    • Price$3.00 / $15.00
    • Context200K
    Full specs Remove Claude Sonnet 4.5
  2. Our pick

    xAI

    Grok 4.3

    Released Apr 17, 2026

    67/100
    • ECI149.2
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.3

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Grok 4.3 is our pick

Grok 4.3 is the better all-round choice, scoring 67/100 against Claude Sonnet 4.5 (55). It leads on capability, price and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGrok 4.3Capabilities Index (ECI): Grok 4.3 149.2 · Claude Sonnet 4.5 146.8
  • Lowest priceGrok 4.3Grok 4.3 $1.56 · Claude Sonnet 4.5 $6.00 per 1M tokens (3:1 blend)
  • Longest contextGrok 4.3Grok 4.3 1,000,000 · Claude Sonnet 4.5 200,000 tokens
  • Widest inputsSame inputsClaude Sonnet 4.5: Text, Images, PDFs · Grok 4.3: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Sonnet 4.5Grok 4.3
CapabilityCapabilities Index (ECI)50%7477
Price25%1341
Inputs & features15%8080
Context window10%3260
Overall100%55/10067/100
02 — Side by side

Every spec in one table

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

Claude Sonnet 4.5 vs Grok 4.3 specifications side by side
SpecificationClaude Sonnet 4.5AnthropicGrok 4.3xAI
Capability
Capabilities Index (ECI)146.8149.2 (best)
ECI rank#64 of 148#55 of 148 (best)
GPQA DiamondGraduate-level science questions82.3%88.8% (best)
FrontierMath Tiers 1–3Research-level mathematics23.9%42.8% (best)
OTIS Mock AIME 2024–2025Competition mathematics77.8%93.3% (best)
SWE-bench VerifiedFixing real GitHub issues71.3%—
SimpleQA VerifiedShort factual questions30.7%33.2% (best)
Price per million tokens
Input$3.00$1.25 (best)
Output$15.00$2.50 (best)
Cached input$0.30$0.20 (best)
Blended (3:1)$6.00$1.56 (best)
Long-context rateSame rateOver 200K: $2.50 / $5.00
Price sourceOfficial Anthropic APIOfficial xAI API
Limits
Context window200,000 tokens1,000,000 tokens (best)
Max output64,000 tokens (best)30,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningYesYeslow · medium · high
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDclaude-sonnet-4-5grok-4.3
API providers28 (best)27
ReleasedSep 29, 2025Apr 17, 2026
Knowledge cutoffJul 31, 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.

  • Claude Sonnet 4.5$60.00
  • Grok 4.3$17.50
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 4.5 or Grok 4.3?

Grok 4.3 is the better all-round choice, scoring 67/100 against Claude Sonnet 4.5 (55). It leads on capability, price and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 4.5 or Grok 4.3?

Grok 4.3 is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). Claude Sonnet 4.5 costs $3.00 input / $15.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.3 versus $6.00 for Claude Sonnet 4.5 (3.8× as much).

Which scores higher on benchmarks?

Grok 4.3 scores higher on the Capabilities Index (ECI): Grok 4.3 149.2 (#55 of 148) and Claude Sonnet 4.5 146.8 (#64 of 148). The confidence ranges of the top two overlap (147.6–150.8 vs 145.3–148.5), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.3 88.8%, Claude Sonnet 4.5 82.3%; FrontierMath Tiers 1–3 — Grok 4.3 42.8%, Claude Sonnet 4.5 23.9%; OTIS Mock AIME 2024–2025 — Grok 4.3 93.3%, Claude Sonnet 4.5 77.8%; SimpleQA Verified — Grok 4.3 33.2%, Claude Sonnet 4.5 30.7%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.3 yet, so there is no like-for-like coding score. On overall capability, Grok 4.3 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?

Grok 4.3 has the largest context window at 1,000,000 tokens, against 200,000 for Claude Sonnet 4.5. Maximum output per response: Claude Sonnet 4.5 up to 64,000, Grok 4.3 up to 30,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 4.5 accepts text, images and PDFs; Grok 4.3 accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Sonnet 4.5 and Grok 4.3 are proprietary and only available through APIs and apps.

Which is newer?

Grok 4.3 is the newest, released Apr 17, 2026. Claude Sonnet 4.5 came out Sep 29, 2025. Knowledge cutoff: Claude Sonnet 4.5 Jul 31, 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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