ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Grok 4.6 vs GPT-6 Luna

GPT-6 Luna comes out ahead, 78 to 61 on our weighted score, and it is the cheaper option too.

  1. xAI

    Grok 4.6

    Released Aug 12, 2026

    61/100
    • ECI156.6
    • Price$2.00 / $6.00
    • Context500K
    Full specs Remove Grok 4.6
  2. Our pick

    OpenAI

    GPT-6 Luna

    Released Sep 22, 2026

    78/100
    • ECI—
    • Price$0.10 / $0.50
    • Context1.05M
    Full specs Remove GPT-6 Luna

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-6 Luna is our pick

GPT-6 Luna is the better all-round choice, scoring 78/100 against Grok 4.6 (61). It leads on price, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Luna has no Capabilities Index score yet.

  • CapabilityGPT-6 LunaShared benchmarks: GPT-6 Luna 77.4% · Grok 4.6 77.1%
  • Lowest priceGPT-6 LunaGPT-6 Luna $0.20 · Grok 4.6 $3.00 per 1M tokens (3:1 blend)
  • Longest contextGPT-6 LunaGPT-6 Luna 1,050,000 · Grok 4.6 500,000 tokens
  • Widest inputsGPT-6 LunaGrok 4.6: Text, Images · GPT-6 Luna: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGrok 4.6GPT-6 Luna
CapabilityShared benchmarks50%7777
Price25%2783
Inputs & features15%7080
Context window10%4861
Overall100%61/10078/100
02 — Side by side

Every spec in one table

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

Grok 4.6 vs GPT-6 Luna specifications side by side
SpecificationGrok 4.6xAIGPT-6 LunaOpenAI
Capability
Capabilities Index (ECI)156.6—
ECI rank#19 of 148—
GPQA DiamondGraduate-level science questions94.0% (best)90.5%
FrontierMath Tiers 1–3Research-level mathematics66.0%79.0% (best)
OTIS Mock AIME 2024–2025Competition mathematics99.2% (best)98.9%
SimpleQA VerifiedShort factual questions49.3% (best)41.4%
Price per million tokens
Input$2.00$0.10 (best)
Output$6.00$0.50 (best)
Cached input$0.50$0.01 (best)
Blended (3:1)$3.00$0.20 (best)
Long-context rateOver 200K: $4.00 / $12.00Over 272K: $0.20 / $0.75
Price sourceOfficial xAI APIOfficial OpenAI API
Limits
Context window500,000 tokens1,050,000 tokens (best)
Max output500,000 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhighYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgrok-4.6gpt-6-luna
API providers29 (best)24
ReleasedAug 12, 2026Sep 22, 2026
Knowledge cutoffFeb 1, 2026May 18, 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.

  • Grok 4.6$32.00
  • GPT-6 Luna$2.00
04 — Questions

Which should you choose?

Which is better: Grok 4.6 or GPT-6 Luna?

GPT-6 Luna is the better all-round choice, scoring 78/100 against Grok 4.6 (61). It leads on price, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6 Luna has no Capabilities Index score yet.

Which is cheaper, Grok 4.6 or GPT-6 Luna?

GPT-6 Luna is cheaper at $0.10 input / $0.50 output per million tokens (official OpenAI API price). Grok 4.6 costs $2.00 input / $6.00 output per million tokens (official xAI API price). At a typical mix of three input tokens to one output token, that is $0.20 per million tokens for GPT-6 Luna versus $3.00 for Grok 4.6 (15× as much).

Which scores higher on benchmarks?

Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6 Luna 77.4% and Grok 4.6 77.1%. On individual benchmarks: GPQA Diamond — Grok 4.6 94.0%, GPT-6 Luna 90.5%; FrontierMath Tiers 1–3 — GPT-6 Luna 79.0%, Grok 4.6 66.0%; OTIS Mock AIME 2024–2025 — Grok 4.6 99.2%, GPT-6 Luna 98.9%; SimpleQA Verified — Grok 4.6 49.3%, GPT-6 Luna 41.4%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.6 and GPT-6 Luna yet, so there is no like-for-like coding score. On overall capability, GPT-6 Luna 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?

GPT-6 Luna has the largest context window at 1,050,000 tokens, against 500,000 for Grok 4.6. Maximum output per response: Grok 4.6 up to 500,000, GPT-6 Luna up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Grok 4.6 accepts text and images; GPT-6 Luna accepts text, images and PDFs. GPT-6 Luna handles the widest range of inputs.

Are any of these open source?

No. Grok 4.6 and GPT-6 Luna are proprietary and only available through APIs and apps.

Which is newer?

GPT-6 Luna is the newest, released Sep 22, 2026. Grok 4.6 came out Aug 12, 2026. Knowledge cutoff: Grok 4.6 Feb 1, 2026, GPT-6 Luna May 18, 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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