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Comparison · 2 models · Updated Oct 4, 2026

GPT-6 Luna vs Gemini 2.5 Flash-Lite

Gemini 2.5 Flash-Lite comes out ahead, 85 to 78 on our weighted score, and it is the cheaper option too.

  1. OpenAI

    GPT-6 Luna

    Released Sep 22, 2026

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

    Google

    Gemini 2.5 Flash-Lite

    Released Jun 17, 2025

    85/100
    • ECI133.9
    • Price$0.10 / $0.40
    • Context1.05M
    Full specs Remove Gemini 2.5 Flash-Lite

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Gemini 2.5 Flash-Lite is our pick

Gemini 2.5 Flash-Lite is the better all-round choice, scoring 85/100 against GPT-6 Luna (78). It leads on price and inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

  • CapabilityNot enough dataNo independent benchmark covers every model here yet
  • Lowest priceGemini 2.5 Flash-LiteGemini 2.5 Flash-Lite $0.175 · GPT-6 Luna $0.20 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameGPT-6 Luna 1,050,000 · Gemini 2.5 Flash-Lite 1,048,576 tokens
  • Widest inputsGemini 2.5 Flash-LiteGPT-6 Luna: Text, Images, PDFs · Gemini 2.5 Flash-Lite: Text, Images, PDFs, Audio, Video
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-6 LunaGemini 2.5 Flash-Lite
Price50%8386
Inputs & features30%80100
Context window20%6161
Overall100%78/10085/100

Left out because at least one model lacks the data: capability. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

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

GPT-6 Luna vs Gemini 2.5 Flash-Lite specifications side by side
SpecificationGPT-6 LunaOpenAIGemini 2.5 Flash-LiteGoogle
Capability
Capabilities Index (ECI)—133.9
ECI rank—#118 of 148
GPQA DiamondGraduate-level science questions90.5%—
FrontierMath Tiers 1–3Research-level mathematics79.0%—
OTIS Mock AIME 2024–2025Competition mathematics98.9%—
SimpleQA VerifiedShort factual questions41.4%—
Price per million tokens
Input$0.10$0.10
Output$0.50$0.40 (best)
Cached input$0.01$0.01
Blended (3:1)$0.20$0.175 (best)
Long-context rateOver 272K: $0.20 / $0.75Same rate
Price sourceOfficial OpenAI APIOfficial Google API
Limits
Context window1,050,000 tokens (best)1,048,576 tokens
Max output128,000 tokens (best)65,536 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoYes
VideoNoYes
ReasoningYeslow · medium · high · xhigh · maxYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-6-lunagemini-2.5-flash-lite
API providers24 (best)20
ReleasedSep 22, 2026Jun 17, 2025
Knowledge cutoffMay 18, 2026Jan 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-6 Luna$2.00
  • Gemini 2.5 Flash-Lite$1.80
04 — Questions

Which should you choose?

Which is better: GPT-6 Luna or Gemini 2.5 Flash-Lite?

Gemini 2.5 Flash-Lite is the better all-round choice, scoring 85/100 against GPT-6 Luna (78). It leads on price and inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

Which is cheaper, GPT-6 Luna or Gemini 2.5 Flash-Lite?

Gemini 2.5 Flash-Lite is cheaper at $0.10 input / $0.40 output per million tokens (official Google API price). GPT-6 Luna costs $0.10 input / $0.50 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $0.175 per million tokens for Gemini 2.5 Flash-Lite versus $0.20 for GPT-6 Luna (1.1× as much).

Which scores higher on benchmarks?

There is no independent benchmark that covers both models yet. GPT-6 Luna has not been scored yet and Gemini 2.5 Flash-Lite has an ECI of 133.9.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-6 Luna and Gemini 2.5 Flash-Lite yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.

Which has the bigger context window?

Their context windows are effectively the same size: GPT-6 Luna 1,050,000 and Gemini 2.5 Flash-Lite 1,048,576 tokens. Maximum output per response: GPT-6 Luna up to 128,000, Gemini 2.5 Flash-Lite up to 65,536 tokens.

Which can read images, PDFs, audio or video?

GPT-6 Luna accepts text, images and PDFs; Gemini 2.5 Flash-Lite accepts text, images, PDFs, audio and video. Gemini 2.5 Flash-Lite handles the widest range of inputs.

Are any of these open source?

No. GPT-6 Luna and Gemini 2.5 Flash-Lite are proprietary and only available through APIs and apps.

Which is newer?

GPT-6 Luna is the newest, released Sep 22, 2026. Gemini 2.5 Flash-Lite came out Jun 17, 2025. Knowledge cutoff: GPT-6 Luna May 18, 2026, Gemini 2.5 Flash-Lite Jan 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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