ZMIME
Comparison · 3 models · Updated Oct 4, 2026

Claude Sonnet 4.5 vs Claude Sonnet 4.6 vs o3

Claude Sonnet 4.6 comes out ahead, 62 to 58 and 55 on our weighted score, though o3 is 42% cheaper per token.

  1. Anthropic

    Claude Sonnet 4.5

    Released Sep 29, 2025

    55/100
    • ECI146.8
    • Price$3.00 / $15.00
    • Context200K
    Full specs Remove Claude Sonnet 4.5
  2. Our pick

    Anthropic

    Claude Sonnet 4.6

    Released Feb 17, 2026

    62/100
    • ECI152.3
    • Price$3.00 / $15.00
    • Context1M
    Full specs Remove Claude Sonnet 4.6

  3. OpenAI

    o3

    Released Apr 16, 2025

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

Claude Sonnet 4.6 is our pick

Claude Sonnet 4.6 is the better all-round choice, scoring 62/100 against o3 (58) and Claude Sonnet 4.5 (55). It leads on capability and context window. o3 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 4.6Capabilities Index (ECI): Claude Sonnet 4.6 152.3 · o3 146.9 · Claude Sonnet 4.5 146.8
  • Lowest priceo3o3 $3.50 · Claude Sonnet 4.5 $6.00 · Claude Sonnet 4.6 $6.00 per 1M tokens (3:1 blend)
  • Longest contextClaude Sonnet 4.6Claude Sonnet 4.6 1,000,000 · Claude Sonnet 4.5 200,000 · o3 200,000 tokens
  • Widest inputsSame inputsClaude Sonnet 4.5: Text, Images, PDFs · Claude Sonnet 4.6: Text, Images, PDFs · o3: Text, Images, PDFs
  • Self-hostingNo open weightsAll three are available only through APIs
How the score is built
MeasureWeightClaude Sonnet 4.5Claude Sonnet 4.6o3
CapabilityCapabilities Index (ECI)50%748174
Price25%131324
Inputs & features15%808080
Context window10%326032
Overall100%55/10062/10058/100
02 — Side by side

Every spec in one table

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

Claude Sonnet 4.5 vs Claude Sonnet 4.6 vs o3 specifications side by side
SpecificationClaude Sonnet 4.5AnthropicClaude Sonnet 4.6Anthropico3OpenAI
Capability
Capabilities Index (ECI)146.8152.3 (best)146.9
ECI rank#64 of 148#40 of 148 (best)#63 of 148
GPQA DiamondGraduate-level science questions82.3%87.4% (best)81.8%
FrontierMath Tiers 1–3Research-level mathematics23.9%—33.3% (best)
OTIS Mock AIME 2024–2025Competition mathematics77.8%85.8% (best)84.4%
SWE-bench VerifiedFixing real GitHub issues71.3%75.2% (best)62.3%
SimpleQA VerifiedShort factual questions30.7%35.5%49.4% (best)
Price per million tokens
Input$3.00$3.00$2.00 (best)
Output$15.00$15.00$8.00 (best)
Cached input$0.30 (best)$0.30 (best)$0.50
Blended (3:1)$6.00$6.00$3.50 (best)
Long-context rateSame rateSame rateSame rate
Price sourceOfficial Anthropic APIOfficial Anthropic APIOfficial OpenAI API
Limits
Context window200,000 tokens1,000,000 tokens (best)200,000 tokens
Max output64,000 tokens64,000 tokens100,000 tokens (best)
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsYesYesYes
AudioNoNoNo
VideoNoNoNo
ReasoningYesYeslow · medium · high · maxYeslow · medium · high
Tool callingYesYesYes
Structured outputYesYesYes
Availability
WeightsProprietaryProprietaryProprietary
API model IDclaude-sonnet-4-5claude-sonnet-4-6o3
API providers2841 (best)18
ReleasedSep 29, 2025Feb 17, 2026Apr 16, 2025
Knowledge cutoffJul 31, 2025Aug 31, 2025May 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 4.5$60.00
  • Claude Sonnet 4.6$60.00
  • o3$36.00
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 4.5, Claude Sonnet 4.6 or o3?

Claude Sonnet 4.6 is the better all-round choice, scoring 62/100 against o3 (58) and Claude Sonnet 4.5 (55). It leads on capability and context window. o3 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 4.5, Claude Sonnet 4.6 or o3?

o3 is cheaper at $2.00 input / $8.00 output per million tokens (official OpenAI API price). Claude Sonnet 4.5 costs $3.00 input / $15.00 output per million tokens (official Anthropic API price); Claude Sonnet 4.6 costs $3.00 input / $15.00 output per million tokens (official Anthropic API price). 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 4.5 (1.7× as much) and $6.00 for Claude Sonnet 4.6 (1.7× as much).

Which scores higher on benchmarks?

Claude Sonnet 4.6 scores higher on the Capabilities Index (ECI): Claude Sonnet 4.6 152.3 (#40 of 148), o3 146.9 (#63 of 148) and Claude Sonnet 4.5 146.8 (#64 of 148). Their confidence ranges do not overlap (149.6–154.7 vs 144.9–148.6), so the gap is a real one. On individual benchmarks: GPQA Diamond — Claude Sonnet 4.6 87.4%, Claude Sonnet 4.5 82.3%, o3 81.8%; OTIS Mock AIME 2024–2025 — Claude Sonnet 4.6 85.8%, o3 84.4%, Claude Sonnet 4.5 77.8%; SWE-bench Verified — Claude Sonnet 4.6 75.2%, Claude Sonnet 4.5 71.3%, o3 62.3%; SimpleQA Verified — o3 49.4%, Claude Sonnet 4.6 35.5%, Claude Sonnet 4.5 30.7%.

Which is better for coding?

Claude Sonnet 4.6 resolves more real GitHub issues on SWE-bench Verified: Claude Sonnet 4.6 75.2%, Claude Sonnet 4.5 71.3% and o3 62.3%. All three support tool calling for agent workflows.

Which has the bigger context window?

Claude Sonnet 4.6 has the largest context window at 1,000,000 tokens, against 200,000 for Claude Sonnet 4.5 and 200,000 for o3. Maximum output per response: Claude Sonnet 4.5 up to 64,000, Claude Sonnet 4.6 up to 64,000, o3 up to 100,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 4.5 accepts text, images and PDFs; Claude Sonnet 4.6 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 4.5, Claude Sonnet 4.6 and o3 are proprietary and only available through APIs and apps.

Which is newer?

Claude Sonnet 4.6 is the newest, released Feb 17, 2026. Claude Sonnet 4.5 came out Sep 29, 2025; o3 came out Apr 16, 2025. Knowledge cutoff: Claude Sonnet 4.5 Jul 31, 2025, Claude Sonnet 4.6 Aug 31, 2025, 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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