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Comparison · 2 models · Updated Oct 4, 2026

Claude Opus 4.8 vs Kimi K3

Too close to call on our weighted score (Kimi K3 65, Claude Opus 4.8 63). The right pick depends on what you value most.

  1. Anthropic

    Claude Opus 4.8

    Released May 28, 2026

    63/100
    • ECI158.3
    • Price$5.00 / $25.00
    • Context1M
    Full specs Remove Claude Opus 4.8

  2. Moonshot AI

    Kimi K3

    Released Jul 16, 2026

    65/100
    • ECI157.6
    • Price$3.00 / $15.00
    • Context1.05M
    Full specs Remove Kimi K3

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 2 points (Kimi K3 65/100, Claude Opus 4.8 63/100), so choose by what matters most for your work: Claude Opus 4.8 for raw capability, Kimi K3 on price and Kimi K3 for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Opus 4.8Capabilities Index (ECI): Claude Opus 4.8 158.3 · Kimi K3 157.6
  • Lowest priceKimi K3Kimi K3 $6.00 · Claude Opus 4.8 $10.00 per 1M tokens (3:1 blend)
  • Longest contextKimi K3Kimi K3 1,048,576 · Claude Opus 4.8 1,000,000 tokens
  • Widest inputsSame inputsClaude Opus 4.8: Text, Images, PDFs · Kimi K3: Text, Images, Video
  • Self-hostingKimi K3Publishes downloadable weights
How the score is built
MeasureWeightClaude Opus 4.8Kimi K3
CapabilityCapabilities Index (ECI)50%8988
Price25%213
Inputs & features15%8080
Context window10%6061
Overall100%63/10065/100
02 — Side by side

Every spec in one table

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

Claude Opus 4.8 vs Kimi K3 specifications side by side
SpecificationClaude Opus 4.8AnthropicKimi K3Moonshot AI
Capability
Capabilities Index (ECI)158.3 (best)157.6
ECI rank#12 of 148 (best)#13 of 148
GPQA DiamondGraduate-level science questions91.0%93.1% (best)
FrontierMath Tiers 1–3Research-level mathematics80.0% (best)72.2%
OTIS Mock AIME 2024–2025Competition mathematics98.3% (best)97.2%
SimpleQA VerifiedShort factual questions53.0% (best)50.6%
Price per million tokens
Input$5.00$3.00 (best)
Output$25.00$15.00 (best)
Cached input$0.50$0.30 (best)
Blended (3:1)$10.00$6.00 (best)
Long-context rateSame rateSame rate
Price sourceOfficial Anthropic APIOfficial Moonshot AI API
Limits
Context window1,000,000 tokens1,048,576 tokens (best)
Max output128,000 tokens131,072 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesNo
AudioNoNo
VideoNoYes
ReasoningYeslow · medium · high · xhigh · maxYeslow · high · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryOpen
API model IDclaude-opus-4-8kimi-k3
API providers4568 (best)
ReleasedMay 28, 2026Jul 16, 2026
Knowledge cutoffJan 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 Opus 4.8$100.00
  • Kimi K3$60.00
04 — Questions

Which should you choose?

Which is better: Claude Opus 4.8 or Kimi K3?

It is close. Our weighted score puts them within 2 points (Kimi K3 65/100, Claude Opus 4.8 63/100), so choose by what matters most for your work: Claude Opus 4.8 for raw capability, Kimi K3 on price and Kimi K3 for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Claude Opus 4.8 or Kimi K3?

Kimi K3 is cheaper at $3.00 input / $15.00 output per million tokens (official Moonshot AI API price). Claude Opus 4.8 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $6.00 per million tokens for Kimi K3 versus $10.00 for Claude Opus 4.8 (1.7× as much).

Which scores higher on benchmarks?

Claude Opus 4.8 scores higher on the Capabilities Index (ECI): Claude Opus 4.8 158.3 (#12 of 148) and Kimi K3 157.6 (#13 of 148). The confidence ranges of the top two overlap (156.1–160.7 vs 154.9–160.4), so treat the gap as small. On individual benchmarks: GPQA Diamond — Kimi K3 93.1%, Claude Opus 4.8 91.0%; FrontierMath Tiers 1–3 — Claude Opus 4.8 80.0%, Kimi K3 72.2%; OTIS Mock AIME 2024–2025 — Claude Opus 4.8 98.3%, Kimi K3 97.2%; SimpleQA Verified — Claude Opus 4.8 53.0%, Kimi K3 50.6%.

Which is better for coding?

There are no published SWE-bench Verified results for Claude Opus 4.8 and Kimi K3 yet, so there is no like-for-like coding score. On overall capability, Claude Opus 4.8 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?

Kimi K3 has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Opus 4.8. Maximum output per response: Claude Opus 4.8 up to 128,000, Kimi K3 up to 131,072 tokens.

Which can read images, PDFs, audio or video?

Claude Opus 4.8 accepts text, images and PDFs; Kimi K3 accepts text, images and video. They handle the same number of input types.

Are any of these open source?

Kimi K3 publishes its weights and can be self-hosted; Claude Opus 4.8 is proprietary.

Which is newer?

Kimi K3 is the newest, released Jul 16, 2026. Claude Opus 4.8 came out May 28, 2026. Knowledge cutoff: Claude Opus 4.8 Jan 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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