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Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 3.5 v2 vs o3

o3 comes out ahead, 58 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

    OpenAI

    o3

    Released Apr 16, 2025

    58/100
    • ECI146.9
    • Price$2.00 / $8.00
    • Context200K
    Full specs Remove o3

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

o3 is our pick

o3 is the better all-round choice, scoring 58/100 against Claude Sonnet 3.5 v2 (44). It leads on capability, price and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • Capabilityo3Capabilities Index (ECI): o3 146.9 · Claude Sonnet 3.5 v2 133.5
  • Lowest priceo3o3 $3.50 · Claude Sonnet 3.5 v2 $6.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Sonnet 3.5 v2 200,000 · o3 200,000 tokens
  • Widest inputsSame inputsClaude Sonnet 3.5 v2: Text, Images, PDFs · o3: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Sonnet 3.5 v2o3
CapabilityCapabilities Index (ECI)50%5774
Price25%1324
Inputs & features15%6080
Context window10%3232
Overall100%44/10058/100
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 o3 specifications side by side
SpecificationClaude Sonnet 3.5 v2Anthropico3OpenAI
Capability
Capabilities Index (ECI)133.5146.9 (best)
ECI rank#119 of 148#63 of 148 (best)
GPQA DiamondGraduate-level science questions55.3%81.8% (best)
FrontierMath Tiers 1–3Research-level mathematics—33.3%
OTIS Mock AIME 2024–2025Competition mathematics8.5%84.4% (best)
SWE-bench VerifiedFixing real GitHub issues—62.3%
SimpleQA VerifiedShort factual questions—49.4%
Price per million tokens
Input$3.00$2.00 (best)
Output$15.00$8.00 (best)
Cached input—$0.50
Blended (3:1)$6.00$3.50 (best)
Long-context rateSame rateSame rate
Price sourceMedian of 1 providersOfficial OpenAI API
Limits
Context window200,000 tokens200,000 tokens
Max output8,192 tokens100,000 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningNoYeslow · medium · high
Tool callingYesYes
Structured outputNoYes
Availability
WeightsProprietaryProprietary
API model ID—o3
API providers118 (best)
ReleasedOct 22, 2024Apr 16, 2025
Knowledge cutoffApr 30, 2024May 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
  • o3$36.00
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 3.5 v2 or o3?

o3 is the better all-round choice, scoring 58/100 against Claude Sonnet 3.5 v2 (44). It leads on capability, price and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 3.5 v2 or o3?

o3 is cheaper at $2.00 input / $8.00 output per million tokens (official OpenAI API price). 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 $3.50 per million tokens for o3 versus $6.00 for Claude Sonnet 3.5 v2 (1.7× as much).

Which scores higher on benchmarks?

o3 scores higher on the Capabilities Index (ECI): o3 146.9 (#63 of 148) and Claude Sonnet 3.5 v2 133.5 (#119 of 148). Their confidence ranges do not overlap (144.9–148.6 vs 129.2–137.5), so the gap is a real one. On individual benchmarks: GPQA Diamond — o3 81.8%, Claude Sonnet 3.5 v2 55.3%; OTIS Mock AIME 2024–2025 — o3 84.4%, Claude Sonnet 3.5 v2 8.5%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Sonnet 3.5 v2 yet, so there is no like-for-like coding score. On overall capability, o3 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 and o3 share the same 200,000-token context window. Maximum output per response: Claude Sonnet 3.5 v2 up to 8,192, o3 up to 100,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 3.5 v2 accepts text, images and PDFs; o3 accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Sonnet 3.5 v2 and o3 are proprietary and only available through APIs and apps.

Which is newer?

o3 is the newest, released Apr 16, 2025. Claude Sonnet 3.5 v2 came out Oct 22, 2024. Knowledge cutoff: Claude Sonnet 3.5 v2 Apr 30, 2024, o3 May 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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