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Head-to-head comparison

Kimi K3 vs GPT-6 Astra

Kimi K3 (Moonshot AI) and GPT-6 Astra (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 9 September 2026

As of 9 September 2026, GPT-6 Astra holds the stronger ModelCap Index position (#1 vs #6); and Kimi K3 is 3.3× cheaper per output token ($15.00/1M vs $50.00/1M).

Which should you choose?

Choose Kimi K3 if…

  • API cost matters — $15.00/1M output tokens against $50.00/1M, about 3.3× cheaper.
  • your workload is prompt-heavy — input tokens cost $3.00/1M against $10.00/1M.
  • you want provider choice — 16 listed API providers against 2.

Choose GPT-6 Astra if…

  • you want the stronger overall ModelCap Index position — #1 against #6 (93.7 vs 82.6 points).
  • LMArena Agent is your yardstick — 12.5% against 6.6%.
  • ARC-AGI-2 is your yardstick — 95.0% against 60.4%.
  • AA Intelligence Index is your yardstick — 52.8 against 43.8.
  • AA Terminal-Bench 2.1 is your yardstick — 88.4% against 85.0%.
  • AA Humanity's Last Exam is your yardstick — 54.7% against 46.9%.
  • you want the more recently listed model — GPT-6 Astra was listed 4 September 2026, Kimi K3 16 July 2026.

Kimi K3 vs GPT-6 Astra: specs, pricing and context

Specification comparison of Kimi K3 and GPT-6 Astra
FieldKimi K3Moonshot AIGPT-6 AstraOpenAI
ModelCap Index position#6#1
Index score82.693.7
EvidenceMeasuredMeasured
Input price / 1M tokens$3.00$10.00
Output price / 1M tokens$15.00$50.00
Context window1M tokens1M tokens
Max output tokens944K128K
API providers listed162
Weight accessRestricted licenseAPI only
Input modalitiesText, Image, VideoFile, Image, Text
First listed16 July 20264 September 2026
PublisherMoonshot AIOpenAI

Evidence: 6 public benchmark observations across 6 boards · 4 public benchmark observations across 4 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Kimi K3 vs GPT-6 Astra

Public benchmark boards where Kimi K3 or GPT-6 Astra has a published result
BoardKimi K3GPT-6 AstraLeads
Arena codingArena (LMArena)15421533–1551Max—Only one result
LMArena AgentLMArena6.6%5.9%–7.3%Max12.5%10.4%–14.7%MaxGPT-6 Astra
ARC-AGI-2ARC Prize Foundation60.4%Max95.0%MaxGPT-6 Astra
ARC-AGI-3ARC Prize Foundation—62.7%MaxOnly one result
AA Intelligence IndexArtificial Analysis43.8intelligence-index:v4.3:max52.8intelligence-index:v4.3:maxGPT-6 Astra
AA Terminal-Bench 2.1Artificial Analysis85.0%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="Kimi K3 (max)":reasoning=true88.4%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GPT-6 Astra (max)":reasoning=trueGPT-6 Astra
AA Humanity's Last ExamArtificial Analysis46.9%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Kimi K3 (max)":reasoning=true54.7%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GPT-6 Astra (max)":reasoning=trueGPT-6 Astra
Terminal-Bench 4.0Terminal-Bench (Laude Institute)—58.2%55.4%–61.0%Codex · MaxOnly one result
WildClawBench OpenClawWildClawBench54.5—Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Kimi K3 vs GPT-6 Astra: common questions

Is Kimi K3 better than GPT-6 Astra?

GPT-6 Astra ranks higher on the ModelCap Index as of 9 September 2026: #1 against #6. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is Kimi K3 cheaper than GPT-6 Astra?

Kimi K3 is cheaper on output tokens: $15.00/1M against $50.00/1M. Input tokens are $3.00/1M for Kimi K3 and $10.00/1M for GPT-6 Astra. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $13.50 for Kimi K3 versus $45.00 for GPT-6 Astra. Kimi K3 costs 70.0% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, Kimi K3 or GPT-6 Astra?

Both publish a 1M-token context window.

Which is better for coding, Kimi K3 or GPT-6 Astra?

AA Terminal-Bench 2.1: Kimi K3 85.0%, GPT-6 Astra 88.4% — GPT-6 Astra leads.

Are Kimi K3 and GPT-6 Astra open-weight models?

Kimi K3: Restricted license. GPT-6 Astra: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Kimi K3 and GPT-6 Astra?

ModelCap currently lists 16 API providers for Kimi K3 and 2 for GPT-6 Astra, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Kimi K3 vs GPT-6 Astra comparison?

Every figure comes from the sealed ModelCap dataset published 9 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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