GPT-5.4 mini vs Grok 4.3 vs Kimi K2.8 Preview
Grok 4.3 comes out ahead, 72 to 66 and 60 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.4 mini
60/100- ECI148.8
- Price$0.75 / $4.50
- Context400K
- Our pick
xAIGrok 4.3
72/100- ECI149.2
- Price$1.25 / $2.50
- Context1M
Moonshot AIKimi K2.8 Preview
66/100- ECI—
- Price—
- Context1.05M
Grok 4.3 is our pick
Grok 4.3 is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66) and GPT-5.4 mini (60). It leads on inputs & features. The score weighs inputs & features 60%, context window 40%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceGrok 4.3Grok 4.3 $1.56 · GPT-5.4 mini $1.69 per 1M tokens (3:1 blend) · Kimi K2.8 Preview unpriced
- Longest contextKimi K2.8 PreviewKimi K2.8 Preview 1,048,576 · Grok 4.3 1,000,000 · GPT-5.4 mini 400,000 tokens
- Widest inputsGrok 4.3 and Kimi K2.8 PreviewGPT-5.4 mini: Text, Images · Grok 4.3: Text, Images, PDFs · Kimi K2.8 Preview: Text, Images, Video
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | GPT-5.4 mini | Grok 4.3 | Kimi K2.8 Preview |
|---|---|---|---|---|
| Inputs & features | 60% | 70 | 80 | 70 |
| Context window | 40% | 44 | 60 | 61 |
| Overall | 100% | 60/100 | 72/100 | 66/100 |
Left out because at least one model lacks the data: capability and price. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.4 miniOpenAI | Grok 4.3xAI | Kimi K2.8 PreviewMoonshot AI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 148.8 | 149.2 (best) | — |
| ECI rank | #56 of 148 | #55 of 148 (best) | — |
| GPQA DiamondGraduate-level science questions | 86.9% | 88.8% (best) | — |
| FrontierMath Tiers 1–3Research-level mathematics | 51.2% (best) | 42.8% | — |
| OTIS Mock AIME 2024–2025Competition mathematics | 88.9% | 93.3% (best) | — |
| SimpleQA VerifiedShort factual questions | 29.4% | 33.2% (best) | — |
| Price per million tokens | |||
| Input | $0.75 (best) | $1.25 | — |
| Output | $4.50 | $2.50 (best) | — |
| Cached input | $0.075 (best) | $0.20 | — |
| Blended (3:1) | $1.69 | $1.56 (best) | — |
| Long-context rate | Same rate | Over 200K: $2.50 / $5.00 | — |
| Price source | Official OpenAI API | Official xAI API | — |
| Limits | |||
| Context window | 400,000 tokens | 1,000,000 tokens | 1,048,576 tokens (best) |
| Max output | 128,000 tokens (best) | 30,000 tokens | — |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | No |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yeslow · medium · high · xhigh | Yeslow · medium · high | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | No |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gpt-5.4-mini | grok-4.3 | — |
| API providers | 29 (best) | 27 | — |
| Released | Mar 17, 2026 | Apr 17, 2026 | Sep 11, 2026 |
| Knowledge cutoff | Aug 31, 2025 | — | — |
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 mini$16.50
- Grok 4.3$17.50
- Kimi K2.8 Preview—
Which should you choose?
Which is better: GPT-5.4 mini, Grok 4.3 or Kimi K2.8 Preview?
Grok 4.3 is the better all-round choice, scoring 72/100 against Kimi K2.8 Preview (66) and GPT-5.4 mini (60). It leads on inputs & features. The score weighs inputs & features 60%, context window 40%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, GPT-5.4 mini, Grok 4.3 or Kimi K2.8 Preview?
Grok 4.3 is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). GPT-5.4 mini costs $0.75 input / $4.50 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.3 versus $1.69 for GPT-5.4 mini (1.1× as much). Kimi K2.8 Preview has no published per-token price.
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. GPT-5.4 mini has an ECI of 148.8, Grok 4.3 has an ECI of 149.2 and Kimi K2.8 Preview has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.4 mini, Grok 4.3 and Kimi K2.8 Preview yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Kimi K2.8 Preview has the largest context window at 1,048,576 tokens, against 1,000,000 for Grok 4.3 and 400,000 for GPT-5.4 mini. Maximum output per response: GPT-5.4 mini up to 128,000, Grok 4.3 up to 30,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.4 mini accepts text and images; Grok 4.3 accepts text, images and PDFs; Kimi K2.8 Preview accepts text, images and video. Grok 4.3 handles the widest range of inputs.
Are any of these open source?
No. GPT-5.4 mini, Grok 4.3 and Kimi K2.8 Preview are proprietary and only available through APIs and apps.
Which is newer?
Kimi K2.8 Preview is the newest, released Sep 11, 2026. Grok 4.3 came out Apr 17, 2026; GPT-5.4 mini came out Mar 17, 2026. Knowledge cutoff: GPT-5.4 mini Aug 31, 2025.
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.
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