ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Claude Opus 4.1 vs GLM-5.1

GLM-5.1 comes out ahead, 57 to 49 on our weighted score, and it is the cheaper option too.

  1. Anthropic

    Claude Opus 4.1

    Released Aug 5, 2025

    49/100
    • ECI144.1
    • Price$15.00 / $75.00
    • Context200K
    Full specs Remove Claude Opus 4.1
  2. Our pick

    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

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GLM-5.1 is our pick

GLM-5.1 is the better all-round choice, scoring 57/100 against Claude Opus 4.1 (49). It leads on capability and price. Claude Opus 4.1 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGLM-5.1Capabilities Index (ECI): GLM-5.1 149.9 · Claude Opus 4.1 144.1
  • Lowest priceGLM-5.1GLM-5.1 $2.15 · Claude Opus 4.1 $30.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Opus 4.1 200,000 · GLM-5.1 200,000 tokens
  • Widest inputsClaude Opus 4.1Claude Opus 4.1: Text, Images, PDFs · GLM-5.1: Text
  • Self-hostingGLM-5.1Publishes downloadable weights
How the score is built
MeasureWeightClaude Opus 4.1GLM-5.1
CapabilityCapabilities Index (ECI)50%7178
Price25%034
Inputs & features15%7045
Context window10%3232
Overall100%49/10057/100
02 — Side by side

Every spec in one table

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

Claude Opus 4.1 vs GLM-5.1 specifications side by side
SpecificationClaude Opus 4.1AnthropicGLM-5.1Z.ai (Zhipu)
Capability
Capabilities Index (ECI)144.1149.9 (best)
ECI rank#81 of 148#51 of 148 (best)
GPQA DiamondGraduate-level science questions77.3%89.9% (best)
FrontierMath Tiers 1–3Research-level mathematics12.6%36.8% (best)
OTIS Mock AIME 2024–2025Competition mathematics68.9%93.3% (best)
SWE-bench VerifiedFixing real GitHub issues73.4%74.2% (best)
SimpleQA VerifiedShort factual questions—34.0%
Price per million tokens
Input$15.00$1.40 (best)
Output$75.00$4.40 (best)
Cached input—$0.26
Blended (3:1)$30.00$2.15 (best)
Long-context rateSame rateSame rate
Price sourceMedian of 14 providersOfficial Z.AI API
Limits
Context window200,000 tokens200,000 tokens
Max output32,000 tokens131,072 tokens (best)
Inputs and features
TextYesYes
ImagesYesNo
PDFsYesNo
AudioNoNo
VideoNoNo
ReasoningYesYes
Tool callingYesYes
Structured outputNoYes
Availability
WeightsProprietaryOpen
API model ID—glm-5.1
API providers1440 (best)
ReleasedAug 5, 2025Apr 7, 2026
Knowledge cutoffMar 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 Opus 4.1$300.00
  • GLM-5.1$22.80
04 — Questions

Which should you choose?

Which is better: Claude Opus 4.1 or GLM-5.1?

GLM-5.1 is the better all-round choice, scoring 57/100 against Claude Opus 4.1 (49). It leads on capability and price. Claude Opus 4.1 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Opus 4.1 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 Opus 4.1 costs $15.00 input / $75.00 output per million tokens (median across 14 API providers). At a typical mix of three input tokens to one output token, that is $2.15 per million tokens for GLM-5.1 versus $30.00 for Claude Opus 4.1 (14× 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 Opus 4.1 144.1 (#81 of 148). Their confidence ranges do not overlap (148.0–151.6 vs 141.6–146.0), so the gap is a real one. On individual benchmarks: GPQA Diamond — GLM-5.1 89.9%, Claude Opus 4.1 77.3%; FrontierMath Tiers 1–3 — GLM-5.1 36.8%, Claude Opus 4.1 12.6%; OTIS Mock AIME 2024–2025 — GLM-5.1 93.3%, Claude Opus 4.1 68.9%; SWE-bench Verified — GLM-5.1 74.2%, Claude Opus 4.1 73.4%.

Which is better for coding?

GLM-5.1 resolves more real GitHub issues on SWE-bench Verified: GLM-5.1 74.2% and Claude Opus 4.1 73.4%. Both support tool calling for agent workflows.

Which has the bigger context window?

Claude Opus 4.1 and GLM-5.1 share the same 200,000-token context window. Maximum output per response: Claude Opus 4.1 up to 32,000, GLM-5.1 up to 131,072 tokens.

Which can read images, PDFs, audio or video?

Claude Opus 4.1 accepts text, images and PDFs; GLM-5.1 accepts text. Claude Opus 4.1 handles the widest range of inputs.

Are any of these open source?

GLM-5.1 publishes its weights and can be self-hosted; Claude Opus 4.1 is proprietary.

Which is newer?

GLM-5.1 is the newest, released Apr 7, 2026. Claude Opus 4.1 came out Aug 5, 2025. Knowledge cutoff: Claude Opus 4.1 Mar 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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