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Comparison · 2 models · Updated Oct 4, 2026

DeepSeek V4.1 Flash vs Claude Opus 5.5

DeepSeek V4.1 Flash comes out ahead, 78 to 70 on our weighted score, and it is the cheaper option too.

  1. Our pick

    DeepSeek

    DeepSeek V4.1 Flash

    Released Sep 10, 2026

    78/100
    • ECI155.0
    • Price$0.15 / $0.60
    • Context1M
    Full specs Remove DeepSeek V4.1 Flash

  2. Anthropic

    Claude Opus 5.5

    Released Sep 22, 2026

    70/100
    • ECI167.4
    • Price$4.00 / $20.00
    • Context1M
    Full specs Remove Claude Opus 5.5

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

DeepSeek V4.1 Flash is our pick

DeepSeek V4.1 Flash is the better all-round choice, scoring 78/100 against Claude Opus 5.5 (70). It leads on price. Claude Opus 5.5 wins on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Opus 5.5Capabilities Index (ECI): Claude Opus 5.5 167.4 · DeepSeek V4.1 Flash 155.0
  • Lowest priceDeepSeek V4.1 FlashDeepSeek V4.1 Flash $0.263 · Claude Opus 5.5 $8.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameDeepSeek V4.1 Flash 1,000,000 · Claude Opus 5.5 1,000,000 tokens
  • Widest inputsClaude Opus 5.5DeepSeek V4.1 Flash: Text, Images · Claude Opus 5.5: Text, Images, PDFs
  • Self-hostingDeepSeek V4.1 FlashPublishes downloadable weights (MIT)
How the score is built
MeasureWeightDeepSeek V4.1 FlashClaude Opus 5.5
CapabilityCapabilities Index (ECI)50%84100
Price25%777
Inputs & features15%7080
Context window10%6060
Overall100%78/10070/100
02 — Side by side

Every spec in one table

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

DeepSeek V4.1 Flash vs Claude Opus 5.5 specifications side by side
SpecificationDeepSeek V4.1 FlashDeepSeekClaude Opus 5.5Anthropic
Capability
Capabilities Index (ECI)155.0167.4 (best)
ECI rank#29 of 148#1 of 148 (best)
GPQA DiamondGraduate-level science questions—90.6%
FrontierMath Tiers 1–3Research-level mathematics—91.2%
OTIS Mock AIME 2024–2025Competition mathematics—100%
SimpleQA VerifiedShort factual questions—72.2%
Price per million tokens
Input$0.15 (best)$4.00
Output$0.60 (best)$20.00
Cached input$0.003 (best)$0.20
Blended (3:1)$0.263 (best)$8.00
Long-context rateSame rateSame rate
Price sourceOfficial DeepSeek APIOfficial Anthropic API
Limits
Context window1,000,000 tokens1,000,000 tokens
Max output384,000 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · high · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsOpenMITProprietary
API model IDdeepseek-flashclaude-opus-5-5
API providers50 (best)28
ReleasedSep 10, 2026Sep 22, 2026
Knowledge cutoffMay 2025Jun 2026
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 V4.1 Flash$2.70
  • Claude Opus 5.5$80.00
04 — Questions

Which should you choose?

Which is better: DeepSeek V4.1 Flash or Claude Opus 5.5?

DeepSeek V4.1 Flash is the better all-round choice, scoring 78/100 against Claude Opus 5.5 (70). It leads on price. Claude Opus 5.5 wins on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, DeepSeek V4.1 Flash or Claude Opus 5.5?

DeepSeek V4.1 Flash is cheaper at $0.15 input / $0.60 output per million tokens (official DeepSeek API price). Claude Opus 5.5 costs $4.00 input / $20.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $0.263 per million tokens for DeepSeek V4.1 Flash versus $8.00 for Claude Opus 5.5 (30× as much).

Which scores higher on benchmarks?

Claude Opus 5.5 scores higher on the Capabilities Index (ECI): Claude Opus 5.5 167.4 (#1 of 148) and DeepSeek V4.1 Flash 155.0 (#29 of 148). Their confidence ranges do not overlap (164.0–172.0 vs 148.8–157.6), so the gap is a real one.

Which is better for coding?

There are no published SWE-bench Verified results for DeepSeek V4.1 Flash and Claude Opus 5.5 yet, so there is no like-for-like coding score. On overall capability, Claude Opus 5.5 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?

DeepSeek V4.1 Flash and Claude Opus 5.5 share the same 1,000,000-token context window. Maximum output per response: DeepSeek V4.1 Flash up to 384,000, Claude Opus 5.5 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

DeepSeek V4.1 Flash accepts text and images; Claude Opus 5.5 accepts text, images and PDFs. Claude Opus 5.5 handles the widest range of inputs.

Are any of these open source?

DeepSeek V4.1 Flash publishes its weights (MIT) and can be self-hosted; Claude Opus 5.5 is proprietary.

Which is newer?

Claude Opus 5.5 is the newest, released Sep 22, 2026. DeepSeek V4.1 Flash came out Sep 10, 2026. Knowledge cutoff: DeepSeek V4.1 Flash May 2025, Claude Opus 5.5 Jun 2026.

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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