ZMIME
Comparison · 3 models · Updated Oct 4, 2026

Claude Opus 4.1 vs GLM-5.1 vs o3-pro

GLM-5.1 comes out ahead, 57 to 51 and 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. OpenAI

    o3-pro

    Released Jun 10, 2025

    51/100
    • ECI147.4
    • Price$20.00 / $80.00
    • Context200K
    Full specs Remove o3-pro
01 — Verdict

GLM-5.1 is our pick

GLM-5.1 is the better all-round choice, scoring 57/100 against o3-pro (51) and Claude Opus 4.1 (49). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGLM-5.1Capabilities Index (ECI): GLM-5.1 149.9 · o3-pro 147.4 · Claude Opus 4.1 144.1
  • Lowest priceGLM-5.1GLM-5.1 $2.15 · Claude Opus 4.1 $30.00 · o3-pro $35.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Opus 4.1 200,000 · GLM-5.1 200,000 · o3-pro 200,000 tokens
  • Widest inputsClaude Opus 4.1Claude Opus 4.1: Text, Images, PDFs · GLM-5.1: Text · o3-pro: Text, Images
  • Self-hostingGLM-5.1Publishes downloadable weights
How the score is built
MeasureWeightClaude Opus 4.1GLM-5.1o3-pro
CapabilityCapabilities Index (ECI)50%717875
Price25%0340
Inputs & features15%704570
Context window10%323232
Overall100%49/10057/10051/100
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 vs o3-pro specifications side by side
SpecificationClaude Opus 4.1AnthropicGLM-5.1Z.ai (Zhipu)o3-proOpenAI
Capability
Capabilities Index (ECI)144.1149.9 (best)147.4
ECI rank#81 of 148#51 of 148 (best)#60 of 148
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)$20.00
Output$75.00$4.40 (best)$80.00
Cached input—$0.26—
Blended (3:1)$30.00$2.15 (best)$35.00
Long-context rateSame rateSame rateSame rate
Price sourceMedian of 14 providersOfficial Z.AI APIOfficial OpenAI API
Limits
Context window200,000 tokens200,000 tokens200,000 tokens
Max output32,000 tokens131,072 tokens (best)100,000 tokens
Inputs and features
TextYesYesYes
ImagesYesNoYes
PDFsYesNoNo
AudioNoNoNo
VideoNoNoNo
ReasoningYesYesYeslow · medium · high
Tool callingYesYesYes
Structured outputNoYesYes
Availability
WeightsProprietaryOpenProprietary
API model ID—glm-5.1o3-pro
API providers1440 (best)6
ReleasedAug 5, 2025Apr 7, 2026Jun 10, 2025
Knowledge cutoffMar 31, 2025—May 2024
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
  • o3-pro$360.00
04 — Questions

Which should you choose?

Which is better: Claude Opus 4.1, GLM-5.1 or o3-pro?

GLM-5.1 is the better all-round choice, scoring 57/100 against o3-pro (51) and Claude Opus 4.1 (49). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Opus 4.1, GLM-5.1 or o3-pro?

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); o3-pro costs $20.00 input / $80.00 output per million tokens (official OpenAI 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 $30.00 for Claude Opus 4.1 (14× as much) and $35.00 for o3-pro (16× 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), o3-pro 147.4 (#60 of 148) and Claude Opus 4.1 144.1 (#81 of 148). The confidence ranges of the top two overlap (148.0–151.6 vs 145.8–149.7), so treat the gap as small.

Which is better for coding?

There are no published SWE-bench Verified results for o3-pro yet, so there is no like-for-like coding score. On overall capability, GLM-5.1 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?

Claude Opus 4.1, GLM-5.1 and o3-pro 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, o3-pro up to 100,000 tokens.

Which can read images, PDFs, audio or video?

Claude Opus 4.1 accepts text, images and PDFs; GLM-5.1 accepts text; o3-pro accepts text and images. 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 and o3-pro is proprietary.

Which is newer?

GLM-5.1 is the newest, released Apr 7, 2026. Claude Opus 4.1 came out Aug 5, 2025; o3-pro came out Jun 10, 2025. Knowledge cutoff: Claude Opus 4.1 Mar 31, 2025, o3-pro May 2024.

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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