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Comparison · 3 models · Updated Nov 2, 2026

DeepSeek-V3.1 vs Gemini 2.5 Flash Preview 05-20 vs GPT OSS 120B

Gemini 2.5 Flash Preview 05-20 comes out ahead, 67 to 58 and 56 on our weighted score, though GPT OSS 120B is 2.3× cheaper per token.

  1. DeepSeek

    DeepSeek-V3.1

    Released Aug 21, 2025

    56/100
    • ECI139.8
    • Price$0.27 / $1.00
    • Context131K
    Full specs Remove DeepSeek-V3.1
  2. Our pick

    Google

    Gemini 2.5 Flash Preview 05-20

    Released May 20, 2025

    67/100
    • ECI141.5
    • Price$0.146 / $1.96
    • Context1.05M
    Full specs Remove Gemini 2.5 Flash Preview 05-20

  3. OpenAI

    GPT OSS 120B

    Released Aug 5, 2025

    58/100
    • ECI139.8
    • Price$0.15 / $0.60
    • Context131K
    Full specs Remove GPT OSS 120B
01 — Verdict

Gemini 2.5 Flash Preview 05-20 is our pick

Gemini 2.5 Flash Preview 05-20 is the better all-round choice, scoring 67/100 against GPT OSS 120B (58) and DeepSeek-V3.1 (56). It leads on capability, inputs & features and context window. GPT OSS 120B wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGemini 2.5 Flash Preview 05-20Capabilities Index (ECI): Gemini 2.5 Flash Preview 05-20 141.5 · DeepSeek-V3.1 139.8 · GPT OSS 120B 139.8
  • Lowest priceGPT OSS 120BGPT OSS 120B $0.263 · DeepSeek-V3.1 $0.453 · Gemini 2.5 Flash Preview 05-20 $0.60 per 1M tokens (3:1 blend)
  • Longest contextGemini 2.5 Flash Preview 05-20Gemini 2.5 Flash Preview 05-20 1,048,576 · DeepSeek-V3.1 131,072 · GPT OSS 120B 131,072 tokens
  • Widest inputsGemini 2.5 Flash Preview 05-20DeepSeek-V3.1: Text · Gemini 2.5 Flash Preview 05-20: Text, Images, PDFs, Audio, Video · GPT OSS 120B: Text
  • Self-hostingDeepSeek-V3.1 and GPT OSS 120BPublishes downloadable weights (MIT License)
How the score is built
MeasureWeightDeepSeek-V3.1Gemini 2.5 Flash Preview 05-20GPT OSS 120B
CapabilityCapabilities Index (ECI)50%646664
Price25%635874
Inputs & features15%359035
Context window10%256125
Overall100%56/10067/10058/100
02 — Side by side

Every spec in one table

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

DeepSeek-V3.1 vs Gemini 2.5 Flash Preview 05-20 vs GPT OSS 120B specifications side by side
SpecificationDeepSeek-V3.1DeepSeekGemini 2.5 Flash Preview 05-20GoogleGPT OSS 120BOpenAI
Capability
Capabilities Index (ECI)139.8141.5 (best)139.8
ECI rank#113 of 165#106 of 165 (best)#114 of 165
GPQA DiamondGraduate-level science questions——75.8%
OTIS Mock AIME 2024–2025Competition mathematics—70.8%88.9% (best)
Price per million tokens
Input$0.27$0.146 (best)$0.15
Output$1.00$1.96$0.60 (best)
Cached input———
Blended (3:1)$0.453$0.60$0.263 (best)
Long-context rateSame rateSame rateSame rate
Price sourceMedian of 19 providersMedian of 2 providersMedian of 65 providers
Limits
Context window131,072 tokens1,048,576 tokens (best)131,072 tokens
Max output8,192 tokens65,536 tokens (best)32,768 tokens
Inputs and features
TextYesYesYes
ImagesNoYesNo
PDFsNoYesNo
AudioNoYesNo
VideoNoYesNo
ReasoningYesYesYes
Tool callingYesYesYes
Structured outputNoNoNo
Availability
WeightsOpenMIT LicenseProprietaryOpen
API model ID———
API providers19267 (best)
ReleasedAug 21, 2025May 20, 2025Aug 5, 2025
Knowledge cutoff—Jan 2025Jun 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.

  • DeepSeek-V3.1$4.70
  • Gemini 2.5 Flash Preview 05-20$5.39
  • GPT OSS 120B$2.70
04 — Questions

Which should you choose?

Which is better: DeepSeek-V3.1, Gemini 2.5 Flash Preview 05-20 or GPT OSS 120B?

Gemini 2.5 Flash Preview 05-20 is the better all-round choice, scoring 67/100 against GPT OSS 120B (58) and DeepSeek-V3.1 (56). It leads on capability, inputs & features and context window. GPT OSS 120B wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, DeepSeek-V3.1, Gemini 2.5 Flash Preview 05-20 or GPT OSS 120B?

GPT OSS 120B is cheaper at $0.15 input / $0.60 output per million tokens (median across 65 API providers). DeepSeek-V3.1 costs $0.27 input / $1.00 output per million tokens (median across 19 API providers); Gemini 2.5 Flash Preview 05-20 costs $0.146 input / $1.96 output per million tokens (median across 2 API providers). At a typical mix of three input tokens to one output token, that is $0.263 per million tokens for GPT OSS 120B versus $0.453 for DeepSeek-V3.1 (1.7× as much) and $0.60 for Gemini 2.5 Flash Preview 05-20 (2.3× as much).

Which scores higher on benchmarks?

Gemini 2.5 Flash Preview 05-20 scores higher on the Capabilities Index (ECI): Gemini 2.5 Flash Preview 05-20 141.5 (#106 of 165), DeepSeek-V3.1 139.8 (#113 of 165) and GPT OSS 120B 139.8 (#114 of 165). The confidence ranges of the top two overlap (139.3–142.9 vs 135.6–143.2), so treat the gap as small.

Which is better for coding?

There are no published SWE-bench Verified results for DeepSeek-V3.1, Gemini 2.5 Flash Preview 05-20 and GPT OSS 120B yet, so there is no like-for-like coding score. On overall capability, Gemini 2.5 Flash Preview 05-20 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 Preview 05-20 has the largest context window at 1,048,576 tokens, against 131,072 for DeepSeek-V3.1 and 131,072 for GPT OSS 120B. Maximum output per response: DeepSeek-V3.1 up to 8,192, Gemini 2.5 Flash Preview 05-20 up to 65,536, GPT OSS 120B up to 32,768 tokens.

Which can read images, PDFs, audio or video?

DeepSeek-V3.1 accepts text; Gemini 2.5 Flash Preview 05-20 accepts text, images, PDFs, audio and video; GPT OSS 120B accepts text. Gemini 2.5 Flash Preview 05-20 handles the widest range of inputs.

Are any of these open source?

DeepSeek-V3.1 and GPT OSS 120B publishes its weights (MIT License) and can be self-hosted; Gemini 2.5 Flash Preview 05-20 is proprietary.

Which is newer?

DeepSeek-V3.1 is the newest, released Aug 21, 2025. GPT OSS 120B came out Aug 5, 2025; Gemini 2.5 Flash Preview 05-20 came out May 20, 2025. Knowledge cutoff: Gemini 2.5 Flash Preview 05-20 Jan 2025, GPT OSS 120B Jun 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 Nov 2, 2026.

05 — Keep comparing

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