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Comparison · 2 models · Updated Oct 4, 2026

o3-mini vs Gemini 2.5 Flash

Gemini 2.5 Flash comes out ahead, 68 to 52 on our weighted score, and it is the cheaper option too.

  1. OpenAI

    o3-mini

    Released Jan 31, 2025Deprecated

    52/100
    • ECI140.3
    • Price$1.10 / $4.40
    • Context200K
    Full specs Remove o3-mini
  2. Our pick

    Google

    Gemini 2.5 Flash

    Released Jun 17, 2025

    68/100
    • ECI140.8
    • Price$0.30 / $2.50
    • Context1.05M
    Full specs Remove Gemini 2.5 Flash

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Gemini 2.5 Flash is our pick

Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against o3-mini (52). It leads on price, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGemini 2.5 FlashCapabilities Index (ECI): Gemini 2.5 Flash 140.8 · o3-mini 140.3
  • Lowest priceGemini 2.5 FlashGemini 2.5 Flash $0.85 · o3-mini $1.93 per 1M tokens (3:1 blend)
  • Longest contextGemini 2.5 FlashGemini 2.5 Flash 1,048,576 · o3-mini 200,000 tokens
  • Widest inputsGemini 2.5 Flasho3-mini: Text · Gemini 2.5 Flash: Text, Images, PDFs, Audio, Video
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeighto3-miniGemini 2.5 Flash
CapabilityCapabilities Index (ECI)50%6667
Price25%3653
Inputs & features15%45100
Context window10%3261
Overall100%52/10068/100
02 — Side by side

Every spec in one table

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

o3-mini vs Gemini 2.5 Flash specifications side by side
Specificationo3-miniOpenAIGemini 2.5 FlashGoogle
Capability
Capabilities Index (ECI)140.3140.8 (best)
ECI rank#98 of 148#97 of 148 (best)
GPQA DiamondGraduate-level science questions77.0%—
FrontierMath Tiers 1–3Research-level mathematics18.6%—
OTIS Mock AIME 2024–2025Competition mathematics76.9%—
SimpleQA VerifiedShort factual questions15.3%—
Price per million tokens
Input$1.10$0.30 (best)
Output$4.40$2.50 (best)
Cached input$0.55$0.03 (best)
Blended (3:1)$1.93$0.85 (best)
Long-context rateSame rateSame rate
Price sourceOfficial OpenAI APIOfficial Google API
Limits
Context window200,000 tokens1,048,576 tokens (best)
Max output100,000 tokens (best)65,536 tokens
Inputs and features
TextYesYes
ImagesNoYes
PDFsNoYes
AudioNoYes
VideoNoYes
ReasoningYeslow · medium · highYes
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDo3-minigemini-2.5-flash
API providers1522 (best)
ReleasedJan 31, 2025Jun 17, 2025
Knowledge cutoffMay 2024Jan 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.

  • o3-mini$19.80
  • Gemini 2.5 Flash$8.00
04 — Questions

Which should you choose?

Which is better: o3-mini or Gemini 2.5 Flash?

Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against o3-mini (52). It leads on price, inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, o3-mini or Gemini 2.5 Flash?

Gemini 2.5 Flash is cheaper at $0.30 input / $2.50 output per million tokens (official Google API price). o3-mini costs $1.10 input / $4.40 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $0.85 per million tokens for Gemini 2.5 Flash versus $1.93 for o3-mini (2.3× as much).

Which scores higher on benchmarks?

Gemini 2.5 Flash scores higher on the Capabilities Index (ECI): Gemini 2.5 Flash 140.8 (#97 of 148) and o3-mini 140.3 (#98 of 148). The confidence ranges of the top two overlap (138.5–142.3 vs 137.4–141.9), so treat the gap as small.

Which is better for coding?

There are no published SWE-bench Verified results for o3-mini and Gemini 2.5 Flash yet, so there is no like-for-like coding score. On overall capability, Gemini 2.5 Flash 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?

Gemini 2.5 Flash has the largest context window at 1,048,576 tokens, against 200,000 for o3-mini. Maximum output per response: o3-mini up to 100,000, Gemini 2.5 Flash up to 65,536 tokens.

Which can read images, PDFs, audio or video?

o3-mini accepts text; Gemini 2.5 Flash accepts text, images, PDFs, audio and video. Gemini 2.5 Flash handles the widest range of inputs.

Are any of these open source?

No. o3-mini and Gemini 2.5 Flash are proprietary and only available through APIs and apps.

Which is newer?

Gemini 2.5 Flash is the newest, released Jun 17, 2025. o3-mini came out Jan 31, 2025. Knowledge cutoff: o3-mini May 2024, Gemini 2.5 Flash 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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