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Comparison · 3 models · Updated Oct 4, 2026

Gemini 2.5 Flash vs o3-mini vs DeepSeek-V3.1

Gemini 2.5 Flash comes out ahead, 68 to 55 and 52 on our weighted score, though DeepSeek-V3.1 is 29% cheaper per token.

  1. 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

  2. OpenAI

    o3-mini

    Released Jan 31, 2025Deprecated

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

  3. DeepSeek

    DeepSeek-V3.1

    Released Aug 21, 2025

    55/100
    • ECI139.9
    • Price$0.385 / $1.25
    • Context131K
    Full specs Remove DeepSeek-V3.1
01 — Verdict

Gemini 2.5 Flash is our pick

Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against DeepSeek-V3.1 (55) and o3-mini (52). It leads on inputs & features and context window. DeepSeek-V3.1 wins on price. 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 · DeepSeek-V3.1 139.9
  • Lowest priceDeepSeek-V3.1DeepSeek-V3.1 $0.601 · Gemini 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 · DeepSeek-V3.1 131,072 tokens
  • Widest inputsGemini 2.5 FlashGemini 2.5 Flash: Text, Images, PDFs, Audio, Video · o3-mini: Text · DeepSeek-V3.1: Text
  • Self-hostingDeepSeek-V3.1Publishes downloadable weights (MIT License)
How the score is built
MeasureWeightGemini 2.5 Flasho3-miniDeepSeek-V3.1
CapabilityCapabilities Index (ECI)50%676665
Price25%533660
Inputs & features15%1004535
Context window10%613224
Overall100%68/10052/10055/100
02 — Side by side

Every spec in one table

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

Gemini 2.5 Flash vs o3-mini vs DeepSeek-V3.1 specifications side by side
SpecificationGemini 2.5 FlashGoogleo3-miniOpenAIDeepSeek-V3.1DeepSeek
Capability
Capabilities Index (ECI)140.8 (best)140.3139.9
ECI rank#97 of 148 (best)#98 of 148#100 of 148
GPQA DiamondGraduate-level science questions—77.0%—
FrontierMath Tiers 1–3Research-level mathematics—18.6%—
OTIS Mock AIME 2024–2025Competition mathematics—76.9%—
SimpleQA VerifiedShort factual questions—15.3%—
Price per million tokens
Input$0.30 (best)$1.10$0.385
Output$2.50$4.40$1.25 (best)
Cached input$0.03 (best)$0.55—
Blended (3:1)$0.85$1.93$0.601 (best)
Long-context rateSame rateSame rateSame rate
Price sourceOfficial Google APIOfficial OpenAI APIMedian of 8 providers
Limits
Context window1,048,576 tokens (best)200,000 tokens131,072 tokens
Max output65,536 tokens100,000 tokens (best)8,192 tokens
Inputs and features
TextYesYesYes
ImagesYesNoNo
PDFsYesNoNo
AudioYesNoNo
VideoYesNoNo
ReasoningYesYeslow · medium · highYes
Tool callingYesYesYes
Structured outputYesYesNo
Availability
WeightsProprietaryProprietaryOpenMIT License
API model IDgemini-2.5-flasho3-mini—
API providers22 (best)158
ReleasedJun 17, 2025Jan 31, 2025Aug 21, 2025
Knowledge cutoffJan 2025May 2024—
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.

  • Gemini 2.5 Flash$8.00
  • o3-mini$19.80
  • DeepSeek-V3.1$6.35
04 — Questions

Which should you choose?

Which is better: Gemini 2.5 Flash, o3-mini or DeepSeek-V3.1?

Gemini 2.5 Flash is the better all-round choice, scoring 68/100 against DeepSeek-V3.1 (55) and o3-mini (52). It leads on inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Gemini 2.5 Flash, o3-mini or DeepSeek-V3.1?

DeepSeek-V3.1 is cheaper at $0.385 input / $1.25 output per million tokens (median across 8 API providers). Gemini 2.5 Flash costs $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 $0.601 per million tokens for DeepSeek-V3.1 versus $0.85 for Gemini 2.5 Flash (1.4× as much) and $1.93 for o3-mini (3.2× 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), o3-mini 140.3 (#98 of 148) and DeepSeek-V3.1 139.9 (#100 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 Gemini 2.5 Flash, o3-mini and DeepSeek-V3.1 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. All three 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 and 131,072 for DeepSeek-V3.1. Maximum output per response: Gemini 2.5 Flash up to 65,536, o3-mini up to 100,000, DeepSeek-V3.1 up to 8,192 tokens.

Which can read images, PDFs, audio or video?

Gemini 2.5 Flash accepts text, images, PDFs, audio and video; o3-mini accepts text; DeepSeek-V3.1 accepts text. Gemini 2.5 Flash handles the widest range of inputs.

Are any of these open source?

DeepSeek-V3.1 publishes its weights (MIT License) and can be self-hosted; Gemini 2.5 Flash and o3-mini is proprietary.

Which is newer?

DeepSeek-V3.1 is the newest, released Aug 21, 2025. Gemini 2.5 Flash came out Jun 17, 2025; o3-mini came out Jan 31, 2025. Knowledge cutoff: Gemini 2.5 Flash Jan 2025, o3-mini May 2024.

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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