GPT-5.5 Pro vs Kimi K3
Too close to call on our weighted score (Kimi K3 65, GPT-5.5 Pro 65). The right pick depends on what you value most.
OpenAIGPT-5.5 Pro
65/100- ECI162.4
- Price$30.00 / $180.00
- Context1.05M
Moonshot AIKimi K3
65/100- ECI157.6
- Price$3.00 / $15.00
- Context1.05M
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Make it a three-way comparison.
Too close to call
It is close. Our weighted score puts them within a point (Kimi K3 65/100, GPT-5.5 Pro 65/100), so choose by what matters most for your work: GPT-5.5 Pro for raw capability and Kimi K3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.5 ProCapabilities Index (ECI): GPT-5.5 Pro 162.4 · Kimi K3 157.6
- Lowest priceKimi K3Kimi K3 $6.00 · GPT-5.5 Pro $67.50 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-5.5 Pro 1,050,000 · Kimi K3 1,048,576 tokens
- Widest inputsSame inputsGPT-5.5 Pro: Text, Images, PDFs · Kimi K3: Text, Images, Video
- Self-hostingKimi K3Publishes downloadable weights
| Measure | Weight | GPT-5.5 Pro | Kimi K3 |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 94 | 88 |
| Price | 25% | 0 | 13 |
| Inputs & features | 15% | 80 | 80 |
| Context window | 10% | 61 | 61 |
| Overall | 100% | 65/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.5 ProOpenAI | Kimi K3Moonshot AI |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 162.4 (best) | 157.6 |
| ECI rank | #6 of 148 (best) | #13 of 148 |
| GPQA DiamondGraduate-level science questions | 93.9% (best) | 93.1% |
| FrontierMath Tiers 1–3Research-level mathematics | 87.7% (best) | 72.2% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 97.2% |
| SimpleQA VerifiedShort factual questions | — | 50.6% |
| Price per million tokens | ||
| Input | $30.00 | $3.00 (best) |
| Output | $180.00 | $15.00 (best) |
| Cached input | — | $0.30 |
| Blended (3:1) | $67.50 | $6.00 (best) |
| Long-context rate | Over 272K: $60.00 / $270.00 | Same rate |
| Price source | Official OpenAI API | Official Moonshot AI API |
| Limits | ||
| Context window | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 128,000 tokens | 131,072 tokens (best) |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | No |
| Audio | No | No |
| Video | No | Yes |
| Reasoning | Yesmedium · high · xhigh | Yeslow · high · max |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Open |
| API model ID | gpt-5.5-pro | kimi-k3 |
| API providers | 19 | 68 (best) |
| Released | Apr 23, 2026 | Jul 16, 2026 |
| Knowledge cutoff | Dec 1, 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-5.5 Pro$660.00
- Kimi K3$60.00
Which should you choose?
Which is better: GPT-5.5 Pro or Kimi K3?
It is close. Our weighted score puts them within a point (Kimi K3 65/100, GPT-5.5 Pro 65/100), so choose by what matters most for your work: GPT-5.5 Pro for raw capability and Kimi K3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.5 Pro or Kimi K3?
Kimi K3 is cheaper at $3.00 input / $15.00 output per million tokens (official Moonshot AI API price). GPT-5.5 Pro costs $30.00 input / $180.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $6.00 per million tokens for Kimi K3 versus $67.50 for GPT-5.5 Pro (11× as much).
Which scores higher on benchmarks?
GPT-5.5 Pro scores higher on the Capabilities Index (ECI): GPT-5.5 Pro 162.4 (#6 of 148) and Kimi K3 157.6 (#13 of 148). The confidence ranges of the top two overlap (159.0–166.0 vs 154.9–160.4), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-5.5 Pro 93.9%, Kimi K3 93.1%; FrontierMath Tiers 1–3 — GPT-5.5 Pro 87.7%, Kimi K3 72.2%; OTIS Mock AIME 2024–2025 — GPT-5.5 Pro 100%, Kimi K3 97.2%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.5 Pro and Kimi K3 yet, so there is no like-for-like coding score. On overall capability, GPT-5.5 Pro leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.
Which has the bigger context window?
Their context windows are effectively the same size: GPT-5.5 Pro 1,050,000 and Kimi K3 1,048,576 tokens. Maximum output per response: GPT-5.5 Pro up to 128,000, Kimi K3 up to 131,072 tokens.
Which can read images, PDFs, audio or video?
GPT-5.5 Pro 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-5.5 Pro is proprietary.
Which is newer?
Kimi K3 is the newest, released Jul 16, 2026. GPT-5.5 Pro came out Apr 23, 2026. Knowledge cutoff: GPT-5.5 Pro Dec 1, 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.
