GPT-5.4 vs GPT-6 Astra vs Kimi K3
Too close to call on our weighted score (GPT-6 Astra 68, Kimi K3 65, GPT-5.4 65). The right pick depends on what you value most.
OpenAIGPT-5.4
65/100- ECI156.9
- Price$2.50 / $15.00
- Context1.05M
- OpenAI
GPT-6 Astra
68/100- ECI166.5
- Price$10.00 / $50.00
- Context1.05M
Moonshot AIKimi K3
65/100- ECI157.6
- Price$3.00 / $15.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within 2 points (GPT-6 Astra 68/100, Kimi K3 65/100, GPT-5.4 65/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and GPT-5.4 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-6 AstraCapabilities Index (ECI): GPT-6 Astra 166.5 · Kimi K3 157.6 · GPT-5.4 156.9
- Lowest priceGPT-5.4GPT-5.4 $5.63 · Kimi K3 $6.00 · GPT-6 Astra $20.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-5.4 1,050,000 · GPT-6 Astra 1,050,000 · Kimi K3 1,048,576 tokens
- Widest inputsSame inputsGPT-5.4: Text, Images, PDFs · GPT-6 Astra: Text, Images, PDFs · Kimi K3: Text, Images, Video
- Self-hostingKimi K3Publishes downloadable weights
| Measure | Weight | GPT-5.4 | GPT-6 Astra | Kimi K3 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 87 | 99 | 88 |
| Price | 25% | 14 | 0 | 13 |
| Inputs & features | 15% | 80 | 80 | 80 |
| Context window | 10% | 61 | 61 | 61 |
| Overall | 100% | 65/100 | 68/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.4OpenAI | GPT-6 AstraOpenAI | Kimi K3Moonshot AI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.9 | 166.5 (best) | 157.6 |
| ECI rank | #16 of 148 | #2 of 148 (best) | #13 of 148 |
| GPQA DiamondGraduate-level science questions | 93.3% | 95.8% (best) | 93.1% |
| FrontierMath Tiers 1–3Research-level mathematics | 78.6% | 93.7% (best) | 72.2% |
| OTIS Mock AIME 2024–2025Competition mathematics | 97.8% | 100% (best) | 97.2% |
| SWE-bench VerifiedFixing real GitHub issues | 76.9% | — | — |
| SimpleQA VerifiedShort factual questions | 45.1% | 75.6% (best) | 50.6% |
| Price per million tokens | |||
| Input | $2.50 (best) | $10.00 | $3.00 |
| Output | $15.00 (best) | $50.00 | $15.00 (best) |
| Cached input | $0.25 (best) | $1.00 | $0.30 |
| Blended (3:1) | $5.63 (best) | $20.00 | $6.00 |
| Long-context rate | Over 272K: $5.00 / $22.50 | Over 272K: $20.00 / $75.00 | Same rate |
| Price source | Official OpenAI API | Official OpenAI API | Official Moonshot AI API |
| Limits | |||
| Context window | 1,050,000 tokens (best) | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 128,000 tokens | 128,000 tokens | 131,072 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | No |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yeslow · medium · high · xhigh | Yeslow · medium · high · xhigh · max | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Open |
| API model ID | gpt-5.4 | gpt-6-astra | kimi-k3 |
| API providers | 36 | 26 | 68 (best) |
| Released | Mar 5, 2026 | Sep 4, 2026 | Jul 16, 2026 |
| Knowledge cutoff | Aug 31, 2025 | Apr 30, 2026 | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.4$55.00
- GPT-6 Astra$200.00
- Kimi K3$60.00
Which should you choose?
Which is better: GPT-5.4, GPT-6 Astra or Kimi K3?
It is close. Our weighted score puts them within 2 points (GPT-6 Astra 68/100, Kimi K3 65/100, GPT-5.4 65/100), so choose by what matters most for your work: GPT-6 Astra for raw capability and GPT-5.4 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.4, GPT-6 Astra or Kimi K3?
GPT-5.4 is cheaper at $2.50 input / $15.00 output per million tokens (official OpenAI API price). Kimi K3 costs $3.00 input / $15.00 output per million tokens (official Moonshot AI API price); GPT-6 Astra costs $10.00 input / $50.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $5.63 per million tokens for GPT-5.4 versus $6.00 for Kimi K3 (1.1× as much) and $20.00 for GPT-6 Astra (3.6× as much).
Which scores higher on benchmarks?
GPT-6 Astra scores higher on the Capabilities Index (ECI): GPT-6 Astra 166.5 (#2 of 148), Kimi K3 157.6 (#13 of 148) and GPT-5.4 156.9 (#16 of 148). Their confidence ranges do not overlap (163.1–171.1 vs 154.9–160.4), so the gap is a real one. On individual benchmarks: GPQA Diamond — GPT-6 Astra 95.8%, GPT-5.4 93.3%, Kimi K3 93.1%; FrontierMath Tiers 1–3 — GPT-6 Astra 93.7%, GPT-5.4 78.6%, Kimi K3 72.2%; OTIS Mock AIME 2024–2025 — GPT-6 Astra 100%, GPT-5.4 97.8%, Kimi K3 97.2%; SimpleQA Verified — GPT-6 Astra 75.6%, Kimi K3 50.6%, GPT-5.4 45.1%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Astra and Kimi K3 yet, so there is no like-for-like coding score. On overall capability, GPT-6 Astra leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.
Which has the bigger context window?
Their context windows are effectively the same size: GPT-5.4 1,050,000, GPT-6 Astra 1,050,000 and Kimi K3 1,048,576 tokens. Maximum output per response: GPT-5.4 up to 128,000, GPT-6 Astra up to 128,000, Kimi K3 up to 131,072 tokens.
Which can read images, PDFs, audio or video?
GPT-5.4 accepts text, images and PDFs; GPT-6 Astra 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; GPT-5.4 and GPT-6 Astra is proprietary.
Which is newer?
GPT-6 Astra is the newest, released Sep 4, 2026. Kimi K3 came out Jul 16, 2026; GPT-5.4 came out Mar 5, 2026. Knowledge cutoff: GPT-5.4 Aug 31, 2025, GPT-6 Astra Apr 30, 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.
