ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GLM-5.3-Flash vs Claude Sonnet 5.5

GLM-5.3-Flash comes out ahead, 80 to 72 on our weighted score, and it is the cheaper option too.

  1. Our pick

    Z.ai (Zhipu)

    GLM-5.3-Flash

    Released Aug 26, 2026

    80/100
    • ECI151.9
    • Price$0.15 / $0.50
    • Context1M
    Full specs Remove GLM-5.3-Flash

  2. Anthropic

    Claude Sonnet 5.5

    Released Sep 28, 2026

    72/100
    • ECI165.2
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5.5

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GLM-5.3-Flash is our pick

GLM-5.3-Flash is the better all-round choice, scoring 80/100 against Claude Sonnet 5.5 (72). It leads on price and inputs & features. Claude Sonnet 5.5 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 5.5Capabilities Index (ECI): Claude Sonnet 5.5 165.2 · GLM-5.3-Flash 151.9
  • Lowest priceGLM-5.3-FlashGLM-5.3-Flash $0.237 · Claude Sonnet 5.5 $4.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameGLM-5.3-Flash 1,000,000 · Claude Sonnet 5.5 1,000,000 tokens
  • Widest inputsGLM-5.3-FlashGLM-5.3-Flash: Text, Images, PDFs, Video · Claude Sonnet 5.5: Text, Images, PDFs
  • Self-hostingGLM-5.3-FlashPublishes downloadable weights
How the score is built
MeasureWeightGLM-5.3-FlashClaude Sonnet 5.5
CapabilityCapabilities Index (ECI)50%8197
Price25%7921
Inputs & features15%9080
Context window10%6060
Overall100%80/10072/100
02 — Side by side

Every spec in one table

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

GLM-5.3-Flash vs Claude Sonnet 5.5 specifications side by side
SpecificationGLM-5.3-FlashZ.ai (Zhipu)Claude Sonnet 5.5Anthropic
Capability
Capabilities Index (ECI)151.9165.2 (best)
ECI rank#42 of 148#3 of 148 (best)
GPQA DiamondGraduate-level science questions90.2%95.6% (best)
FrontierMath Tiers 1–3Research-level mathematics55.8%88.8% (best)
OTIS Mock AIME 2024–2025Competition mathematics93.9%100% (best)
SimpleQA VerifiedShort factual questions—46.5%
Price per million tokens
Input$0.15 (best)$2.00
Output$0.50 (best)$10.00
Cached input$0.03 (best)$0.20
Blended (3:1)$0.237 (best)$4.00
Long-context rateSame rateSame rate
Price sourceOfficial Z.AI APIOfficial Anthropic API
Limits
Context window1,000,000 tokens1,000,000 tokens
Max output131,072 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoYesNo
ReasoningYeslow · high · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsOpenProprietary
API model IDglm-5.3-flashclaude-sonnet-5-5
API providers65 (best)23
ReleasedAug 26, 2026Sep 28, 2026
Knowledge cutoff—Jun 2026
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.

  • GLM-5.3-Flash$2.50
  • Claude Sonnet 5.5$40.00
04 — Questions

Which should you choose?

Which is better: GLM-5.3-Flash or Claude Sonnet 5.5?

GLM-5.3-Flash is the better all-round choice, scoring 80/100 against Claude Sonnet 5.5 (72). It leads on price and inputs & features. Claude Sonnet 5.5 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GLM-5.3-Flash or Claude Sonnet 5.5?

GLM-5.3-Flash is cheaper at $0.15 input / $0.50 output per million tokens (official Z.AI API price). Claude Sonnet 5.5 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 $0.237 per million tokens for GLM-5.3-Flash versus $4.00 for Claude Sonnet 5.5 (17× as much).

Which scores higher on benchmarks?

Claude Sonnet 5.5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5.5 165.2 (#3 of 148) and GLM-5.3-Flash 151.9 (#42 of 148). Their confidence ranges do not overlap (161.8–169.4 vs 149.4–154.3), so the gap is a real one. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, GLM-5.3-Flash 90.2%; FrontierMath Tiers 1–3 — Claude Sonnet 5.5 88.8%, GLM-5.3-Flash 55.8%; OTIS Mock AIME 2024–2025 — Claude Sonnet 5.5 100%, GLM-5.3-Flash 93.9%.

Which is better for coding?

There are no published SWE-bench Verified results for GLM-5.3-Flash and Claude Sonnet 5.5 yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 5.5 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?

GLM-5.3-Flash and Claude Sonnet 5.5 share the same 1,000,000-token context window. Maximum output per response: GLM-5.3-Flash up to 131,072, Claude Sonnet 5.5 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

GLM-5.3-Flash accepts text, images, PDFs and video; Claude Sonnet 5.5 accepts text, images and PDFs. GLM-5.3-Flash handles the widest range of inputs.

Are any of these open source?

GLM-5.3-Flash publishes its weights and can be self-hosted; Claude Sonnet 5.5 is proprietary.

Which is newer?

Claude Sonnet 5.5 is the newest, released Sep 28, 2026. GLM-5.3-Flash came out Aug 26, 2026. Knowledge cutoff: Claude Sonnet 5.5 Jun 2026.

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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