ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GPT-5.6 Luna vs Inkling Small

GPT-5.6 Luna comes out ahead, 78 to 70 on our weighted score, and it is the cheaper option too.

  1. Our pick

    OpenAI

    GPT-5.6 Luna

    Released Jul 9, 2026

    78/100
    • ECI156.5
    • Price$0.20 / $1.20
    • Context1.05M
    Full specs Remove GPT-5.6 Luna

  2. Thinking Machines

    Inkling Small

    Released Jul 30, 2026

    70/100
    • ECI150.2
    • Price$0.50 / $1.20
    • Context1.05M
    Full specs Remove Inkling Small

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-5.6 Luna is our pick

GPT-5.6 Luna is the better all-round choice, scoring 78/100 against Inkling Small (70). It leads on capability, price and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGPT-5.6 LunaCapabilities Index (ECI): GPT-5.6 Luna 156.5 · Inkling Small 150.2
  • Lowest priceGPT-5.6 LunaGPT-5.6 Luna $0.45 · Inkling Small $0.675 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameGPT-5.6 Luna 1,050,000 · Inkling Small 1,048,576 tokens
  • Widest inputsSame inputsGPT-5.6 Luna: Text, Images, PDFs · Inkling Small: Text, Images, Audio
  • Self-hostingInkling SmallPublishes downloadable weights (Apache-2.0)
How the score is built
MeasureWeightGPT-5.6 LunaInkling Small
CapabilityCapabilities Index (ECI)50%8678
Price25%6658
Inputs & features15%8070
Context window10%6161
Overall100%78/10070/100
02 — Side by side

Every spec in one table

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

GPT-5.6 Luna vs Inkling Small specifications side by side
SpecificationGPT-5.6 LunaOpenAIInkling SmallThinking Machines
Capability
Capabilities Index (ECI)156.5 (best)150.2
ECI rank#21 of 148 (best)#47 of 148
GPQA DiamondGraduate-level science questions91.6% (best)88.5%
FrontierMath Tiers 1–3Research-level mathematics82.1% (best)46.3%
OTIS Mock AIME 2024–2025Competition mathematics98.3% (best)90.0%
SimpleQA VerifiedShort factual questions41.0% (best)19.1%
Price per million tokens
Input$0.20 (best)$0.50
Output$1.20$1.20
Cached input$0.02—
Blended (3:1)$0.45 (best)$0.675
Long-context rateOver 272K: $0.40 / $1.80Same rate
Price sourceOfficial OpenAI APIMedian of 11 providers
Limits
Context window1,050,000 tokens (best)1,048,576 tokens
Max output128,000 tokens1,048,576 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesNo
AudioNoYes
VideoNoNo
ReasoningYeslow · medium · high · xhigh · maxYes
Tool callingYesYes
Structured outputYesNo
Availability
WeightsProprietaryOpenApache-2.0
API model IDgpt-5.6-luna—
API providers38 (best)11
ReleasedJul 9, 2026Jul 30, 2026
Knowledge cutoffFeb 16, 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.

  • GPT-5.6 Luna$4.40
  • Inkling Small$7.40
04 — Questions

Which should you choose?

Which is better: GPT-5.6 Luna or Inkling Small?

GPT-5.6 Luna is the better all-round choice, scoring 78/100 against Inkling Small (70). It leads on capability, price and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5.6 Luna or Inkling Small?

GPT-5.6 Luna is cheaper at $0.20 input / $1.20 output per million tokens (official OpenAI API price). Inkling Small costs $0.50 input / $1.20 output per million tokens (median across 11 API providers). At a typical mix of three input tokens to one output token, that is $0.45 per million tokens for GPT-5.6 Luna versus $0.675 for Inkling Small (1.5× as much).

Which scores higher on benchmarks?

GPT-5.6 Luna scores higher on the Capabilities Index (ECI): GPT-5.6 Luna 156.5 (#21 of 148) and Inkling Small 150.2 (#47 of 148). Their confidence ranges do not overlap (154.1–158.6 vs 147.5–152.1), so the gap is a real one. On individual benchmarks: GPQA Diamond — GPT-5.6 Luna 91.6%, Inkling Small 88.5%; FrontierMath Tiers 1–3 — GPT-5.6 Luna 82.1%, Inkling Small 46.3%; OTIS Mock AIME 2024–2025 — GPT-5.6 Luna 98.3%, Inkling Small 90.0%; SimpleQA Verified — GPT-5.6 Luna 41.0%, Inkling Small 19.1%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5.6 Luna and Inkling Small yet, so there is no like-for-like coding score. On overall capability, GPT-5.6 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?

Their context windows are effectively the same size: GPT-5.6 Luna 1,050,000 and Inkling Small 1,048,576 tokens. Maximum output per response: GPT-5.6 Luna up to 128,000, Inkling Small up to 1,048,576 tokens.

Which can read images, PDFs, audio or video?

GPT-5.6 Luna accepts text, images and PDFs; Inkling Small accepts text, images and audio. They handle the same number of input types.

Are any of these open source?

Inkling Small publishes its weights (Apache-2.0) and can be self-hosted; GPT-5.6 Luna is proprietary.

Which is newer?

Inkling Small is the newest, released Jul 30, 2026. GPT-5.6 Luna came out Jul 9, 2026. Knowledge cutoff: GPT-5.6 Luna Feb 16, 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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