ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GLM-5.3 vs Grok 4.20 (Reasoning)

Grok 4.20 (Reasoning) comes out ahead, 68 to 64 on our weighted score, and it is the cheaper option too.

  1. Z.ai (Zhipu)

    GLM-5.3

    Released Aug 14, 2026

    64/100
    • ECI155.8
    • Price$1.40 / $4.40
    • Context1M
    Full specs Remove GLM-5.3
  2. Our pick

    xAI

    Grok 4.20 (Reasoning)

    Released Mar 9, 2026

    68/100
    • ECI152.0
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.20 (Reasoning)

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Grok 4.20 (Reasoning) is our pick

Grok 4.20 (Reasoning) is the better all-round choice, scoring 68/100 against GLM-5.3 (64). It leads on price and inputs & features. GLM-5.3 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGLM-5.3Capabilities Index (ECI): GLM-5.3 155.8 · Grok 4.20 (Reasoning) 152.0
  • Lowest priceGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) $1.56 · GLM-5.3 $2.15 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameGLM-5.3 1,000,000 · Grok 4.20 (Reasoning) 1,000,000 tokens
  • Widest inputsGrok 4.20 (Reasoning)GLM-5.3: Text · Grok 4.20 (Reasoning): Text, Images, PDFs
  • Self-hostingGLM-5.3Publishes downloadable weights
How the score is built
MeasureWeightGLM-5.3Grok 4.20 (Reasoning)
CapabilityCapabilities Index (ECI)50%8581
Price25%3441
Inputs & features15%4580
Context window10%6060
Overall100%64/10068/100
02 — Side by side

Every spec in one table

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

GLM-5.3 vs Grok 4.20 (Reasoning) specifications side by side
SpecificationGLM-5.3Z.ai (Zhipu)Grok 4.20 (Reasoning)xAI
Capability
Capabilities Index (ECI)155.8 (best)152.0
ECI rank#24 of 148 (best)#41 of 148
GPQA DiamondGraduate-level science questions90.9% (best)89.3%
FrontierMath Tiers 1–3Research-level mathematics68.8% (best)44.9%
OTIS Mock AIME 2024–2025Competition mathematics91.1%92.2% (best)
SimpleQA VerifiedShort factual questions41.0% (best)30.2%
Price per million tokens
Input$1.40$1.25 (best)
Output$4.40$2.50 (best)
Cached input$0.26$0.20 (best)
Blended (3:1)$2.15$1.56 (best)
Long-context rateSame rateOver 200K: $2.50 / $5.00
Price sourceOfficial Z.AI APIOfficial xAI API
Limits
Context window1,000,000 tokens1,000,000 tokens
Max output131,072 tokens (best)30,000 tokens
Inputs and features
TextYesYes
ImagesNoYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · high · maxYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsOpenProprietary
API model IDglm-5.3grok-4.20-0309-reasoning
API providers62 (best)11
ReleasedAug 14, 2026Mar 9, 2026
Knowledge cutoff——
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$22.80
  • Grok 4.20 (Reasoning)$17.50
04 — Questions

Which should you choose?

Which is better: GLM-5.3 or Grok 4.20 (Reasoning)?

Grok 4.20 (Reasoning) is the better all-round choice, scoring 68/100 against GLM-5.3 (64). It leads on price and inputs & features. GLM-5.3 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GLM-5.3 or Grok 4.20 (Reasoning)?

Grok 4.20 (Reasoning) is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). GLM-5.3 costs $1.40 input / $4.40 output per million tokens (official Z.AI API price). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.20 (Reasoning) versus $2.15 for GLM-5.3 (1.4× as much).

Which scores higher on benchmarks?

GLM-5.3 scores higher on the Capabilities Index (ECI): GLM-5.3 155.8 (#24 of 148) and Grok 4.20 (Reasoning) 152.0 (#41 of 148). The confidence ranges of the top two overlap (153.7–158.3 vs 149.3–154.4), so treat the gap as small. On individual benchmarks: GPQA Diamond — GLM-5.3 90.9%, Grok 4.20 (Reasoning) 89.3%; FrontierMath Tiers 1–3 — GLM-5.3 68.8%, Grok 4.20 (Reasoning) 44.9%; OTIS Mock AIME 2024–2025 — Grok 4.20 (Reasoning) 92.2%, GLM-5.3 91.1%; SimpleQA Verified — GLM-5.3 41.0%, Grok 4.20 (Reasoning) 30.2%.

Which is better for coding?

There are no published SWE-bench Verified results for GLM-5.3 and Grok 4.20 (Reasoning) yet, so there is no like-for-like coding score. On overall capability, GLM-5.3 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?

GLM-5.3 and Grok 4.20 (Reasoning) share the same 1,000,000-token context window. Maximum output per response: GLM-5.3 up to 131,072, Grok 4.20 (Reasoning) up to 30,000 tokens.

Which can read images, PDFs, audio or video?

GLM-5.3 accepts text; Grok 4.20 (Reasoning) accepts text, images and PDFs. Grok 4.20 (Reasoning) handles the widest range of inputs.

Are any of these open source?

GLM-5.3 publishes its weights and can be self-hosted; Grok 4.20 (Reasoning) is proprietary.

Which is newer?

GLM-5.3 is the newest, released Aug 14, 2026. Grok 4.20 (Reasoning) came out Mar 9, 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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