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Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 3.5 v2 vs DeepSeek-V3.1

DeepSeek-V3.1 comes out ahead, 55 to 44 on our weighted score, and it is the cheaper option too.

  1. Anthropic

    Claude Sonnet 3.5 v2

    Released Oct 22, 2024

    44/100
    • ECI133.5
    • Price$3.00 / $15.00
    • Context200K
    Full specs Remove Claude Sonnet 3.5 v2
  2. Our pick

    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

DeepSeek-V3.1 is our pick

DeepSeek-V3.1 is the better all-round choice, scoring 55/100 against Claude Sonnet 3.5 v2 (44). It leads on capability and price. Claude Sonnet 3.5 v2 wins on inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityDeepSeek-V3.1Capabilities Index (ECI): DeepSeek-V3.1 139.9 · Claude Sonnet 3.5 v2 133.5
  • Lowest priceDeepSeek-V3.1DeepSeek-V3.1 $0.601 · Claude Sonnet 3.5 v2 $6.00 per 1M tokens (3:1 blend)
  • Longest contextClaude Sonnet 3.5 v2Claude Sonnet 3.5 v2 200,000 · DeepSeek-V3.1 131,072 tokens
  • Widest inputsClaude Sonnet 3.5 v2Claude Sonnet 3.5 v2: Text, Images, PDFs · DeepSeek-V3.1: Text
  • Self-hostingDeepSeek-V3.1Publishes downloadable weights (MIT License)
How the score is built
MeasureWeightClaude Sonnet 3.5 v2DeepSeek-V3.1
CapabilityCapabilities Index (ECI)50%5765
Price25%1360
Inputs & features15%6035
Context window10%3224
Overall100%44/10055/100
02 — Side by side

Every spec in one table

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

Claude Sonnet 3.5 v2 vs DeepSeek-V3.1 specifications side by side
SpecificationClaude Sonnet 3.5 v2AnthropicDeepSeek-V3.1DeepSeek
Capability
Capabilities Index (ECI)133.5139.9 (best)
ECI rank#119 of 148#100 of 148 (best)
GPQA DiamondGraduate-level science questions55.3%—
OTIS Mock AIME 2024–2025Competition mathematics8.5%—
Price per million tokens
Input$3.00$0.385 (best)
Output$15.00$1.25 (best)
Cached input——
Blended (3:1)$6.00$0.601 (best)
Long-context rateSame rateSame rate
Price sourceMedian of 1 providersMedian of 8 providers
Limits
Context window200,000 tokens (best)131,072 tokens
Max output8,192 tokens8,192 tokens
Inputs and features
TextYesYes
ImagesYesNo
PDFsYesNo
AudioNoNo
VideoNoNo
ReasoningNoYes
Tool callingYesYes
Structured outputNoNo
Availability
WeightsProprietaryOpenMIT License
API model ID——
API providers18 (best)
ReleasedOct 22, 2024Aug 21, 2025
Knowledge cutoffApr 30, 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.

  • Claude Sonnet 3.5 v2$60.00
  • DeepSeek-V3.1$6.35
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 3.5 v2 or DeepSeek-V3.1?

DeepSeek-V3.1 is the better all-round choice, scoring 55/100 against Claude Sonnet 3.5 v2 (44). It leads on capability and price. Claude Sonnet 3.5 v2 wins on inputs & features and context window. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 3.5 v2 or DeepSeek-V3.1?

DeepSeek-V3.1 is cheaper at $0.385 input / $1.25 output per million tokens (median across 8 API providers). Claude Sonnet 3.5 v2 costs $3.00 input / $15.00 output per million tokens (median across 1 API provider). At a typical mix of three input tokens to one output token, that is $0.601 per million tokens for DeepSeek-V3.1 versus $6.00 for Claude Sonnet 3.5 v2 (10× as much).

Which scores higher on benchmarks?

DeepSeek-V3.1 scores higher on the Capabilities Index (ECI): DeepSeek-V3.1 139.9 (#100 of 148) and Claude Sonnet 3.5 v2 133.5 (#119 of 148). The confidence ranges of the top two overlap (136.1–143.3 vs 129.2–137.5), so treat the gap as small.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Sonnet 3.5 v2 and DeepSeek-V3.1 yet, so there is no like-for-like coding score. On overall capability, DeepSeek-V3.1 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 3.5 v2 has the largest context window at 200,000 tokens, against 131,072 for DeepSeek-V3.1. Maximum output per response: Claude Sonnet 3.5 v2 up to 8,192, DeepSeek-V3.1 up to 8,192 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 3.5 v2 accepts text, images and PDFs; DeepSeek-V3.1 accepts text. Claude Sonnet 3.5 v2 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; Claude Sonnet 3.5 v2 is proprietary.

Which is newer?

DeepSeek-V3.1 is the newest, released Aug 21, 2025. Claude Sonnet 3.5 v2 came out Oct 22, 2024. Knowledge cutoff: Claude Sonnet 3.5 v2 Apr 30, 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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