ZMIME
Comparison · 2 models · Updated Oct 4, 2026

Claude Sonnet 5.5 vs Claude Sonnet 5

Claude Sonnet 5.5 comes out ahead, 72 to 66 on our weighted score.

  1. Our pick

    Anthropic

    Claude Sonnet 5.5

    Released Sep 28, 2026

    72/100
    • ECI165.2
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5.5

  2. Anthropic

    Claude Sonnet 5

    Released Jun 30, 2026

    66/100
    • ECI156.3
    • Price$2.00 / $10.00
    • Context1M
    Full specs Remove Claude Sonnet 5

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Claude Sonnet 5.5 is our pick

Claude Sonnet 5.5 is the better all-round choice, scoring 72/100 against Claude Sonnet 5 (66). It leads on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Sonnet 5.5Capabilities Index (ECI): Claude Sonnet 5.5 165.2 · Claude Sonnet 5 156.3
  • Lowest priceSame priceClaude Sonnet 5.5 $4.00 · Claude Sonnet 5 $4.00 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameClaude Sonnet 5.5 1,000,000 · Claude Sonnet 5 1,000,000 tokens
  • Widest inputsSame inputsClaude Sonnet 5.5: Text, Images, PDFs · Claude Sonnet 5: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightClaude Sonnet 5.5Claude Sonnet 5
CapabilityCapabilities Index (ECI)50%9786
Price25%2121
Inputs & features15%8080
Context window10%6060
Overall100%72/10066/100
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 Claude Sonnet 5 specifications side by side
SpecificationClaude Sonnet 5.5AnthropicClaude Sonnet 5Anthropic
Capability
Capabilities Index (ECI)165.2 (best)156.3
ECI rank#3 of 148 (best)#23 of 148
GPQA DiamondGraduate-level science questions95.6% (best)90.5%
FrontierMath Tiers 1–3Research-level mathematics88.8% (best)65.6%
OTIS Mock AIME 2024–2025Competition mathematics100% (best)94.7%
SimpleQA VerifiedShort factual questions46.5% (best)33.7%
Price per million tokens
Input$2.00$2.00
Output$10.00$10.00
Cached input$0.20$0.20
Blended (3:1)$4.00$4.00
Long-context rateSame rateSame rate
Price sourceOfficial Anthropic APIOfficial Anthropic API
Limits
Context window1,000,000 tokens1,000,000 tokens
Max output128,000 tokens128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhigh · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDclaude-sonnet-5-5claude-sonnet-5
API providers2338 (best)
ReleasedSep 28, 2026Jun 30, 2026
Knowledge cutoffJun 2026Jan 31, 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.

  • Claude Sonnet 5.5$40.00
  • Claude Sonnet 5$40.00
04 — Questions

Which should you choose?

Which is better: Claude Sonnet 5.5 or Claude Sonnet 5?

Claude Sonnet 5.5 is the better all-round choice, scoring 72/100 against Claude Sonnet 5 (66). It leads on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Sonnet 5.5 or Claude Sonnet 5?

Claude Sonnet 5.5 and Claude Sonnet 5 cost the same: $2.00 input / $10.00 output per million tokens.

Which scores higher on benchmarks?

Claude Sonnet 5.5 scores higher on the Capabilities Index (ECI): Claude Sonnet 5.5 165.2 (#3 of 148) and Claude Sonnet 5 156.3 (#23 of 148). Their confidence ranges do not overlap (161.8–169.4 vs 153.6–158.8), so the gap is a real one. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, Claude Sonnet 5 90.5%; FrontierMath Tiers 1–3 — Claude Sonnet 5.5 88.8%, Claude Sonnet 5 65.6%; OTIS Mock AIME 2024–2025 — Claude Sonnet 5.5 100%, Claude Sonnet 5 94.7%; SimpleQA Verified — Claude Sonnet 5.5 46.5%, Claude Sonnet 5 33.7%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Sonnet 5.5 and Claude Sonnet 5 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 Claude Sonnet 5 share the same 1,000,000-token context window. Maximum output per response: Claude Sonnet 5.5 up to 128,000, Claude Sonnet 5 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Claude Sonnet 5.5 accepts text, images and PDFs; Claude Sonnet 5 accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. Claude Sonnet 5.5 and Claude Sonnet 5 are proprietary and only available through APIs and apps.

Which is newer?

Claude Sonnet 5.5 is the newest, released Sep 28, 2026. Claude Sonnet 5 came out Jun 30, 2026. Knowledge cutoff: Claude Sonnet 5.5 Jun 2026, Claude Sonnet 5 Jan 31, 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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