GPT-5.3 Chat vs GPT-5.4 vs Kimi K3
Too close to call on our weighted score (GPT-5.4 43, Kimi K3 43, GPT-5.3 Chat 32). The right pick depends on what you value most.
OpenAIGPT-5.3 Chat
32/100- ECI—
- Price$1.75 / $14.00
- Context128K
- OpenAI
GPT-5.4
43/100- ECI156.9
- Price$2.50 / $15.00
- Context1.05M
Moonshot AIKimi K3
43/100- ECI157.6
- Price$3.00 / $15.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within a point (GPT-5.4 43/100, Kimi K3 43/100, GPT-5.3 Chat 32/100), so choose by what matters most for your work: GPT-5.3 Chat on price. The score weighs price 50%, inputs & features 30%, context window 20%. 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 priceGPT-5.3 ChatGPT-5.3 Chat $4.81 · GPT-5.4 $5.63 · Kimi K3 $6.00 per 1M tokens (3:1 blend)
- Longest contextGPT-5.4 and Kimi K3GPT-5.4 1,050,000 · Kimi K3 1,048,576 · GPT-5.3 Chat 128,000 tokens
- Widest inputsGPT-5.4 and Kimi K3GPT-5.3 Chat: Text, Images · GPT-5.4: Text, Images, PDFs · Kimi K3: Text, Images, Video
- Self-hostingKimi K3Publishes downloadable weights
| Measure | Weight | GPT-5.3 Chat | GPT-5.4 | Kimi K3 |
|---|---|---|---|---|
| Price | 50% | 18 | 14 | 13 |
| Inputs & features | 30% | 60 | 80 | 80 |
| Context window | 20% | 24 | 61 | 61 |
| Overall | 100% | 32/100 | 43/100 | 43/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.3 ChatOpenAI | GPT-5.4OpenAI | 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% (best) | 93.1% |
| FrontierMath Tiers 1–3Research-level mathematics | — | 78.6% (best) | 72.2% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 97.8% (best) | 97.2% |
| SWE-bench VerifiedFixing real GitHub issues | — | 76.9% | — |
| SimpleQA VerifiedShort factual questions | — | 45.1% | 50.6% (best) |
| Price per million tokens | |||
| Input | $1.75 (best) | $2.50 | $3.00 |
| Output | $14.00 (best) | $15.00 | $15.00 |
| Cached input | $0.175 (best) | $0.25 | $0.30 |
| Blended (3:1) | $4.81 (best) | $5.63 | $6.00 |
| Long-context rate | Same rate | Over 272K: $5.00 / $22.50 | Same rate |
| Price source | Official OpenAI API | Official OpenAI API | Official Moonshot AI API |
| Limits | |||
| Context window | 128,000 tokens | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 16,384 tokens | 128,000 tokens | 131,072 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | No |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | No | Yeslow · medium · high · xhigh | Yeslow · high · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Open |
| API model ID | gpt-5.3-chat-latest | gpt-5.4 | kimi-k3 |
| API providers | 4 | 36 | 68 (best) |
| Released | Mar 3, 2026 | Mar 5, 2026 | Jul 16, 2026 |
| Knowledge cutoff | Aug 31, 2025 | 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-5.3 Chat$45.50
- GPT-5.4$55.00
- Kimi K3$60.00
Which should you choose?
Which is better: GPT-5.3 Chat, GPT-5.4 or Kimi K3?
It is close. Our weighted score puts them within a point (GPT-5.4 43/100, Kimi K3 43/100, GPT-5.3 Chat 32/100), so choose by what matters most for your work: GPT-5.3 Chat on price. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, GPT-5.3 Chat, GPT-5.4 or Kimi K3?
GPT-5.3 Chat is cheaper at $1.75 input / $14.00 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 $4.81 per million tokens for GPT-5.3 Chat versus $5.63 for GPT-5.4 (1.2× as much) and $6.00 for Kimi K3 (1.2× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. GPT-5.3 Chat has not been scored yet, GPT-5.4 has an ECI of 156.9 and Kimi K3 has an ECI of 157.6.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.3 Chat and Kimi K3 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?
GPT-5.4 and Kimi K3 have the largest context windows (1,050,000 and 1,048,576 tokens), against 128,000 for GPT-5.3 Chat. Maximum output per response: GPT-5.3 Chat up to 16,384, GPT-5.4 up to 128,000, Kimi K3 up to 131,072 tokens.
Which can read images, PDFs, audio or video?
GPT-5.3 Chat accepts text and images; GPT-5.4 accepts text, images and PDFs; Kimi K3 accepts text, images and video. GPT-5.4 handles the widest range of inputs.
Are any of these open source?
Kimi K3 publishes its weights and can be self-hosted; GPT-5.3 Chat and GPT-5.4 is proprietary.
Which is newer?
Kimi K3 is the newest, released Jul 16, 2026. GPT-5.4 came out Mar 5, 2026; GPT-5.3 Chat came out Mar 3, 2026. Knowledge cutoff: GPT-5.3 Chat Aug 31, 2025, GPT-5.4 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.
