ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 4.5 vs GLM-5.1

Too close to call on our weighted score (GLM-5.1 57, Claude Sonnet 4.5 55). The right pick depends on what you value most.

  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. Z.ai (Zhipu)

    GLM-5.1

    Released Apr 7, 2026

    57/100
    • ECI149.9
    • Price$1.40 / $4.40
    • Context200K
    Full specs Remove GLM-5.1

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 2 points (GLM-5.1 57/100, Claude Sonnet 4.5 55/100), so choose by what matters most for your work: GLM-5.1 for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGLM-5.1Capabilities Index (ECI): GLM-5.1 149.9 · Claude Sonnet 4.5 146.8
  • Lowest priceGLM-5.1GLM-5.1 $2.15 · Claude Sonnet 4.5 $6.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Sonnet 4.5 200,000 · GLM-5.1 200,000 tokens
  • Widest inputsClaude Sonnet 4.5Claude Sonnet 4.5: Text, Images, PDFs · GLM-5.1: Text
  • Self-hostingGLM-5.1Publishes downloadable weights
How the score is built
MeasureWeightClaude Sonnet 4.5GLM-5.1
CapabilityCapabilities Index (ECI)50%7478
Price25%1334
Inputs & features15%8045
Context window10%3232
Overall100%55/10057/100
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 GLM-5.1 specifications side by side
SpecificationClaude Sonnet 4.5AnthropicGLM-5.1Z.ai (Zhipu)
Capability
Capabilities Index (ECI)146.8149.9 (best)
ECI rank#64 of 148#51 of 148 (best)
GPQA DiamondGraduate-level science questions82.3%89.9% (best)
FrontierMath Tiers 1–3Research-level mathematics23.9%36.8% (best)
OTIS Mock AIME 2024–2025Competition mathematics77.8%93.3% (best)
SWE-bench VerifiedFixing real GitHub issues71.3%74.2% (best)
SimpleQA VerifiedShort factual questions30.7%34.0% (best)
Price per million tokens
Input$3.00$1.40 (best)
Output$15.00$4.40 (best)
Cached input$0.30$0.26 (best)
Blended (3:1)$6.00$2.15 (best)
Long-context rateSame rateSame rate
Price sourceOfficial Anthropic APIOfficial Z.AI API
Limits
Context window200,000 tokens200,000 tokens
Max output64,000 tokens131,072 tokens (best)
Inputs and features
TextYesYes
ImagesYesNo
PDFsYesNo
AudioNoNo
VideoNoNo
ReasoningYesYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryOpen
API model IDclaude-sonnet-4-5glm-5.1
API providers2840 (best)
ReleasedSep 29, 2025Apr 7, 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
  • GLM-5.1$22.80
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 4.5 or GLM-5.1?

It is close. Our weighted score puts them within 2 points (GLM-5.1 57/100, Claude Sonnet 4.5 55/100), so choose by what matters most for your work: GLM-5.1 for raw capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 4.5 or GLM-5.1?

GLM-5.1 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI 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 $2.15 per million tokens for GLM-5.1 versus $6.00 for Claude Sonnet 4.5 (2.8× as much).

Which scores higher on benchmarks?

GLM-5.1 scores higher on the Capabilities Index (ECI): GLM-5.1 149.9 (#51 of 148) and Claude Sonnet 4.5 146.8 (#64 of 148). The confidence ranges of the top two overlap (148.0–151.6 vs 145.3–148.5), so treat the gap as small. On individual benchmarks: GPQA Diamond — GLM-5.1 89.9%, Claude Sonnet 4.5 82.3%; FrontierMath Tiers 1–3 — GLM-5.1 36.8%, Claude Sonnet 4.5 23.9%; OTIS Mock AIME 2024–2025 — GLM-5.1 93.3%, Claude Sonnet 4.5 77.8%; SWE-bench Verified — GLM-5.1 74.2%, Claude Sonnet 4.5 71.3%; SimpleQA Verified — GLM-5.1 34.0%, Claude Sonnet 4.5 30.7%.

Which is better for coding?

GLM-5.1 resolves more real GitHub issues on SWE-bench Verified: GLM-5.1 74.2% and Claude Sonnet 4.5 71.3%. Both support tool calling for agent workflows.

Which has the bigger context window?

Claude Sonnet 4.5 and GLM-5.1 share the same 200,000-token context window. Maximum output per response: Claude Sonnet 4.5 up to 64,000, GLM-5.1 up to 131,072 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 4.5 accepts text, images and PDFs; GLM-5.1 accepts text. Claude Sonnet 4.5 handles the widest range of inputs.

Are any of these open source?

GLM-5.1 publishes its weights and can be self-hosted; Claude Sonnet 4.5 is proprietary.

Which is newer?

GLM-5.1 is the newest, released Apr 7, 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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