GPT-5.4 vs GPT-6.1 Sol vs Kimi K3
GPT-6.1 Sol comes out ahead, 69 to 61 and 60 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.4
61/100- ECI156.9
- Price$2.50 / $15.00
- Context1.05M
- Our pickOpenAI
GPT-6.1 Sol
69/100- ECI—
- Price$2.00 / $10.00
- Context1.05M
Moonshot AIKimi K3
60/100- ECI157.6
- Price$3.00 / $15.00
- Context1.05M
GPT-6.1 Sol is our pick
GPT-6.1 Sol is the better all-round choice, scoring 69/100 against GPT-5.4 (61) and Kimi K3 (60). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6.1 Sol has no Capabilities Index score yet.
- CapabilityGPT-6.1 SolShared benchmarks: GPT-6.1 Sol 90.7% · GPT-5.4 78.7% · Kimi K3 78.3%
- Lowest priceGPT-6.1 SolGPT-6.1 Sol $4.00 · GPT-5.4 $5.63 · Kimi K3 $6.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-5.4 1,050,000 · GPT-6.1 Sol 1,050,000 · Kimi K3 1,048,576 tokens
- Widest inputsSame inputsGPT-5.4: Text, Images, PDFs · GPT-6.1 Sol: Text, Images, PDFs · Kimi K3: Text, Images, Video
- Self-hostingKimi K3Publishes downloadable weights
| Measure | Weight | GPT-5.4 | GPT-6.1 Sol | Kimi K3 |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 79 | 91 | 78 |
| Price | 25% | 14 | 21 | 13 |
| Inputs & features | 15% | 80 | 80 | 80 |
| Context window | 10% | 61 | 61 | 61 |
| Overall | 100% | 61/100 | 69/100 | 60/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.4OpenAI | GPT-6.1 SolOpenAI | Kimi K3Moonshot AI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.9 | — | 157.6 (best) |
| ECI rank | #16 of 148 | — | #13 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 93.3% | 95.4% (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% | 73.9% (best) | 50.6% |
| Price per million tokens | |||
| Input | $2.50 | $2.00 (best) | $3.00 |
| Output | $15.00 | $10.00 (best) | $15.00 |
| Cached input | $0.25 | $0.10 (best) | $0.30 |
| Blended (3:1) | $5.63 | $4.00 (best) | $6.00 |
| Long-context rate | Over 272K: $5.00 / $22.50 | Over 272K: $4.00 / $15.00 | 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-6.1-sol | kimi-k3 |
| API providers | 36 | 21 | 68 (best) |
| Released | Mar 5, 2026 | Sep 29, 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-6.1 Sol$40.00
- Kimi K3$60.00
Which should you choose?
Which is better: GPT-5.4, GPT-6.1 Sol or Kimi K3?
GPT-6.1 Sol is the better all-round choice, scoring 69/100 against GPT-5.4 (61) and Kimi K3 (60). It leads on capability and price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6.1 Sol has no Capabilities Index score yet.
Which is cheaper, GPT-5.4, GPT-6.1 Sol or Kimi K3?
GPT-6.1 Sol is cheaper at $2.00 input / $10.00 output per million tokens (official OpenAI API price). GPT-5.4 costs $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). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6.1 Sol versus $5.63 for GPT-5.4 (1.4× as much) and $6.00 for Kimi K3 (1.5× as much).
Which scores higher on benchmarks?
Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6.1 Sol 90.7%, GPT-5.4 78.7% and Kimi K3 78.3%. On individual benchmarks: GPQA Diamond — GPT-6.1 Sol 95.4%, GPT-5.4 93.3%, Kimi K3 93.1%; FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, GPT-5.4 78.6%, Kimi K3 72.2%; OTIS Mock AIME 2024–2025 — GPT-6.1 Sol 100%, GPT-5.4 97.8%, Kimi K3 97.2%; SimpleQA Verified — GPT-6.1 Sol 73.9%, Kimi K3 50.6%, GPT-5.4 45.1%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6.1 Sol and Kimi K3 yet, so there is no like-for-like coding score. On overall capability, GPT-6.1 Sol 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-6.1 Sol 1,050,000 and Kimi K3 1,048,576 tokens. Maximum output per response: GPT-5.4 up to 128,000, GPT-6.1 Sol 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-6.1 Sol 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-6.1 Sol is proprietary.
Which is newer?
GPT-6.1 Sol is the newest, released Sep 29, 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-6.1 Sol 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.
