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Comparison · 2 models · Updated Oct 4, 2026

GPT-5.4 mini vs Grok 4.20 (Reasoning)

Grok 4.20 (Reasoning) comes out ahead, 68 to 63 on our weighted score, and it is the cheaper option too.

  1. OpenAI

    GPT-5.4 mini

    Released Mar 17, 2026

    63/100
    • ECI148.8
    • Price$0.75 / $4.50
    • Context400K
    Full specs Remove GPT-5.4 mini
  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 GPT-5.4 mini (63). It leads on capability, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGrok 4.20 (Reasoning)Capabilities Index (ECI): Grok 4.20 (Reasoning) 152.0 · GPT-5.4 mini 148.8
  • Lowest priceGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) $1.56 · GPT-5.4 mini $1.69 per 1M tokens (3:1 blend)
  • Longest contextGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) 1,000,000 · GPT-5.4 mini 400,000 tokens
  • Widest inputsGrok 4.20 (Reasoning)GPT-5.4 mini: Text, Images · Grok 4.20 (Reasoning): Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.4 miniGrok 4.20 (Reasoning)
CapabilityCapabilities Index (ECI)50%7781
Price25%3941
Inputs & features15%7080
Context window10%4460
Overall100%63/10068/100
02 — Side by side

Every spec in one table

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

GPT-5.4 mini vs Grok 4.20 (Reasoning) specifications side by side
SpecificationGPT-5.4 miniOpenAIGrok 4.20 (Reasoning)xAI
Capability
Capabilities Index (ECI)148.8152.0 (best)
ECI rank#56 of 148#41 of 148 (best)
GPQA DiamondGraduate-level science questions86.9%89.3% (best)
FrontierMath Tiers 1–3Research-level mathematics51.2% (best)44.9%
OTIS Mock AIME 2024–2025Competition mathematics88.9%92.2% (best)
SimpleQA VerifiedShort factual questions29.4%30.2% (best)
Price per million tokens
Input$0.75 (best)$1.25
Output$4.50$2.50 (best)
Cached input$0.075 (best)$0.20
Blended (3:1)$1.69$1.56 (best)
Long-context rateSame rateOver 200K: $2.50 / $5.00
Price sourceOfficial OpenAI APIOfficial xAI API
Limits
Context window400,000 tokens1,000,000 tokens (best)
Max output128,000 tokens (best)30,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhighYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-5.4-minigrok-4.20-0309-reasoning
API providers29 (best)11
ReleasedMar 17, 2026Mar 9, 2026
Knowledge cutoffAug 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.

  • GPT-5.4 mini$16.50
  • Grok 4.20 (Reasoning)$17.50
04 — Questions

Which should you choose?

Which is better: GPT-5.4 mini or Grok 4.20 (Reasoning)?

Grok 4.20 (Reasoning) is the better all-round choice, scoring 68/100 against GPT-5.4 mini (63). It leads on capability, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5.4 mini 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). GPT-5.4 mini costs $0.75 input / $4.50 output per million tokens (official OpenAI 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 $1.69 for GPT-5.4 mini (1.1× as much).

Which scores higher on benchmarks?

Grok 4.20 (Reasoning) scores higher on the Capabilities Index (ECI): Grok 4.20 (Reasoning) 152.0 (#41 of 148) and GPT-5.4 mini 148.8 (#56 of 148). The confidence ranges of the top two overlap (149.3–154.4 vs 147.1–150.5), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.20 (Reasoning) 89.3%, GPT-5.4 mini 86.9%; FrontierMath Tiers 1–3 — GPT-5.4 mini 51.2%, Grok 4.20 (Reasoning) 44.9%; OTIS Mock AIME 2024–2025 — Grok 4.20 (Reasoning) 92.2%, GPT-5.4 mini 88.9%; SimpleQA Verified — Grok 4.20 (Reasoning) 30.2%, GPT-5.4 mini 29.4%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5.4 mini and Grok 4.20 (Reasoning) yet, so there is no like-for-like coding score. On overall capability, Grok 4.20 (Reasoning) 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?

Grok 4.20 (Reasoning) has the largest context window at 1,000,000 tokens, against 400,000 for GPT-5.4 mini. Maximum output per response: GPT-5.4 mini up to 128,000, Grok 4.20 (Reasoning) up to 30,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.4 mini accepts text and images; 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?

No. GPT-5.4 mini and Grok 4.20 (Reasoning) are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.4 mini is the newest, released Mar 17, 2026. Grok 4.20 (Reasoning) came out Mar 9, 2026. Knowledge cutoff: GPT-5.4 mini Aug 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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