ZMIME
Comparison · 2 models · Updated Nov 2, 2026

Claude Sonnet 5.5 vs DeepSeek V4.1 Flash 1017

DeepSeek V4.1 Flash 1017 comes out ahead, 79 to 72 on our weighted score, and it is the cheaper option too.

  1. Anthropic

    Claude Sonnet 5.5

    Released Sep 28, 2026New

    72/100
    • ECI166.7
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5.5
  2. Our pick

    DeepSeek

    DeepSeek V4.1 Flash 1017

    Released Oct 17, 2026New

    79/100
    • ECI158.8
    • Price$0.15 / $0.60
    • Context1M
    Full specs Remove DeepSeek V4.1 Flash 1017

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

DeepSeek V4.1 Flash 1017 is our pick

DeepSeek V4.1 Flash 1017 is the better all-round choice, scoring 79/100 against Claude Sonnet 5.5 (72). It leads on price. Claude Sonnet 5.5 wins on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 5.5Capabilities Index (ECI): Claude Sonnet 5.5 166.7 · DeepSeek V4.1 Flash 1017 158.8
  • Lowest priceDeepSeek V4.1 Flash 1017DeepSeek V4.1 Flash 1017 $0.263 · Claude Sonnet 5.5 $4.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Sonnet 5.5 1,000,000 · DeepSeek V4.1 Flash 1017 1,000,000 tokens
  • Widest inputsClaude Sonnet 5.5Claude Sonnet 5.5: Text, Images, PDFs · DeepSeek V4.1 Flash 1017: Text, Images
  • Self-hostingDeepSeek V4.1 Flash 1017Publishes downloadable weights (MIT)
How the score is built
MeasureWeightClaude Sonnet 5.5DeepSeek V4.1 Flash 1017
CapabilityCapabilities Index (ECI)50%9787
Price25%2074
Inputs & features15%8070
Context window10%6060
Overall100%72/10079/100
02 — Side by side

Every spec in one table

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

Claude Sonnet 5.5 vs DeepSeek V4.1 Flash 1017 specifications side by side
SpecificationClaude Sonnet 5.5AnthropicDeepSeek V4.1 Flash 1017DeepSeek
Capability
Capabilities Index (ECI)166.7 (best)158.8
ECI rank#5 of 165 (best)#19 of 165
GPQA DiamondGraduate-level science questions95.6% (best)93.2%
FrontierMath Tiers 1–3Research-level mathematics88.8% (best)71.2%
OTIS Mock AIME 2024–2025Competition mathematics100% (best)99.4%
SimpleQA VerifiedShort factual questions46.5% (best)42.5%
Price per million tokens
Input$2.00$0.15 (best)
Output$10.00$0.60 (best)
Cached input$0.10$0.003 (best)
Blended (3:1)$4.00$0.263 (best)
Long-context rateSame rateSame rate
Price sourceOfficial Anthropic APIOfficial DeepSeek API
Limits
Context window1,000,000 tokens1,000,000 tokens
Max output128,000 tokens384,000 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesNo
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhigh · maxYeslow · high · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryOpenMIT
API model IDclaude-sonnet-5-5deepseek-flash
API providers3440 (best)
ReleasedSep 28, 2026Oct 17, 2026
Knowledge cutoffJun 2026May 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.

  • Claude Sonnet 5.5$40.00
  • DeepSeek V4.1 Flash 1017$2.70
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 5.5 or DeepSeek V4.1 Flash 1017?

DeepSeek V4.1 Flash 1017 is the better all-round choice, scoring 79/100 against Claude Sonnet 5.5 (72). It leads on price. Claude Sonnet 5.5 wins on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 5.5 or DeepSeek V4.1 Flash 1017?

DeepSeek V4.1 Flash 1017 is cheaper at $0.15 input / $0.60 output per million tokens (official DeepSeek API price). Claude Sonnet 5.5 costs $2.00 input / $10.00 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 1017 versus $4.00 for Claude Sonnet 5.5 (15× as much).

Which scores higher on benchmarks?

Claude Sonnet 5.5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5.5 166.7 (#5 of 165) and DeepSeek V4.1 Flash 1017 158.8 (#19 of 165). Their confidence ranges do not overlap (163.6–171.3 vs 156.7–162.2), so the gap is a real one. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, DeepSeek V4.1 Flash 1017 93.2%; FrontierMath Tiers 1–3 — Claude Sonnet 5.5 88.8%, DeepSeek V4.1 Flash 1017 71.2%; OTIS Mock AIME 2024–2025 — Claude Sonnet 5.5 100%, DeepSeek V4.1 Flash 1017 99.4%; SimpleQA Verified — Claude Sonnet 5.5 46.5%, DeepSeek V4.1 Flash 1017 42.5%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Sonnet 5.5 and DeepSeek V4.1 Flash 1017 yet, so there is no like-for-like coding score. On overall capability, Claude Sonnet 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?

Claude Sonnet 5.5 and DeepSeek V4.1 Flash 1017 share the same 1,000,000-token context window. Maximum output per response: Claude Sonnet 5.5 up to 128,000, DeepSeek V4.1 Flash 1017 up to 384,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 5.5 accepts text, images and PDFs; DeepSeek V4.1 Flash 1017 accepts text and images. Claude Sonnet 5.5 handles the widest range of inputs.

Are any of these open source?

DeepSeek V4.1 Flash 1017 publishes its weights (MIT) and can be self-hosted; Claude Sonnet 5.5 is proprietary.

Which is newer?

DeepSeek V4.1 Flash 1017 is the newest, released Oct 17, 2026. Claude Sonnet 5.5 came out Sep 28, 2026. Knowledge cutoff: Claude Sonnet 5.5 Jun 2026, DeepSeek V4.1 Flash 1017 May 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 Nov 2, 2026.

05 — Keep comparing

Related comparisons