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Comparison · 2 models · Updated Oct 4, 2026

Qwen3.5 Plus vs DeepSeek-V3.1

Qwen3.5 Plus comes out ahead, 66 to 55 on our weighted score, though DeepSeek-V3.1 is 33% cheaper per token.

  1. Our pick

    Alibaba (Qwen)

    Qwen3.5 Plus

    Released Feb 16, 2026

    66/100
    • ECI146.8
    • Price$0.40 / $2.40
    • Context1M
    Full specs Remove Qwen3.5 Plus

  2. DeepSeek

    DeepSeek-V3.1

    Released Aug 21, 2025

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

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Qwen3.5 Plus is our pick

Qwen3.5 Plus is the better all-round choice, scoring 66/100 against DeepSeek-V3.1 (55). It leads on capability, inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityQwen3.5 PlusCapabilities Index (ECI): Qwen3.5 Plus 146.8 · DeepSeek-V3.1 139.9
  • Lowest priceDeepSeek-V3.1DeepSeek-V3.1 $0.601 · Qwen3.5 Plus $0.90 per 1M tokens (3:1 blend)
  • Longest contextQwen3.5 PlusQwen3.5 Plus 1,000,000 · DeepSeek-V3.1 131,072 tokens
  • Widest inputsQwen3.5 PlusQwen3.5 Plus: Text, Images, Video · DeepSeek-V3.1: Text
  • Self-hostingDeepSeek-V3.1Publishes downloadable weights (MIT License)
How the score is built
MeasureWeightQwen3.5 PlusDeepSeek-V3.1
CapabilityCapabilities Index (ECI)50%7465
Price25%5260
Inputs & features15%7035
Context window10%6024
Overall100%66/10055/100
02 — Side by side

Every spec in one table

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

Qwen3.5 Plus vs DeepSeek-V3.1 specifications side by side
SpecificationQwen3.5 PlusAlibaba (Qwen)DeepSeek-V3.1DeepSeek
Capability
Capabilities Index (ECI)146.8 (best)139.9
ECI rank#65 of 148 (best)#100 of 148
GPQA DiamondGraduate-level science questions84.9%—
OTIS Mock AIME 2024–2025Competition mathematics86.7%—
SimpleQA VerifiedShort factual questions25.4%—
Price per million tokens
Input$0.40$0.385 (best)
Output$2.40$1.25 (best)
Cached input——
Blended (3:1)$0.90$0.601 (best)
Long-context rateSame rateSame rate
Price sourceOfficial Alibaba APIMedian of 8 providers
Limits
Context window1,000,000 tokens (best)131,072 tokens
Max output65,536 tokens (best)8,192 tokens
Inputs and features
TextYesYes
ImagesYesNo
PDFsNoNo
AudioNoNo
VideoYesNo
ReasoningYesYes
Tool callingYesYes
Structured outputNoNo
Availability
WeightsProprietaryOpenMIT License
API model IDqwen3.5-plus—
API providers10 (best)8
ReleasedFeb 16, 2026Aug 21, 2025
Knowledge cutoffApr 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.

  • Qwen3.5 Plus$8.80
  • DeepSeek-V3.1$6.35
04 — Questions

Which should you choose?

Which is better: Qwen3.5 Plus or DeepSeek-V3.1?

Qwen3.5 Plus is the better all-round choice, scoring 66/100 against DeepSeek-V3.1 (55). It leads on capability, 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, Qwen3.5 Plus or DeepSeek-V3.1?

DeepSeek-V3.1 is cheaper at $0.385 input / $1.25 output per million tokens (median across 8 API providers). Qwen3.5 Plus costs $0.40 input / $2.40 output per million tokens (official Alibaba 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 $0.90 for Qwen3.5 Plus (1.5× as much).

Which scores higher on benchmarks?

Qwen3.5 Plus scores higher on the Capabilities Index (ECI): Qwen3.5 Plus 146.8 (#65 of 148) and DeepSeek-V3.1 139.9 (#100 of 148). Their confidence ranges do not overlap (144.6–148.1 vs 136.1–143.3), so the gap is a real one.

Which is better for coding?

There are no published SWE-bench Verified results for Qwen3.5 Plus and DeepSeek-V3.1 yet, so there is no like-for-like coding score. On overall capability, Qwen3.5 Plus 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?

Qwen3.5 Plus has the largest context window at 1,000,000 tokens, against 131,072 for DeepSeek-V3.1. Maximum output per response: Qwen3.5 Plus up to 65,536, DeepSeek-V3.1 up to 8,192 tokens.

Which can read images, PDFs, audio or video?

Qwen3.5 Plus accepts text, images and video; DeepSeek-V3.1 accepts text. Qwen3.5 Plus 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; Qwen3.5 Plus is proprietary.

Which is newer?

Qwen3.5 Plus is the newest, released Feb 16, 2026. DeepSeek-V3.1 came out Aug 21, 2025. Knowledge cutoff: Qwen3.5 Plus Apr 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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