GPT-5.1 Medium vs Kimi K3: Specs & Benchmark Comparison
GPT-5.1 Medium is developed by OpenAI, while Kimi K3 comes from Moonshot AI. GPT-5.1 Medium was released in November 2025, and Kimi K3 followed 8 months later in July 2026. Kimi K3 has a published size of about 2.8 trillion parameters; OpenAI has not disclosed the parameter count of GPT-5.1 Medium.
We have 1 benchmark result for GPT-5.1 Medium and 3 benchmark results for Kimi K3, but they were measured on different benchmarks, so there is no like-for-like scoreboard.
GPT-5.1 Medium is the cheaper API at $1 per million input tokens and $4 per million output tokens, roughly 3 times cheaper than Kimi K3 at $3 and $15. Kimi K3 takes the larger context window at 1M tokens, compared with 256K for GPT-5.1 Medium. Both accept text and images as input.
| Characteristic | GPT-5.1 Medium | Kimi K3 |
|---|---|---|
| Company | OpenAI | Moonshot AI |
| Release Date | November 11, 2025 | July 16, 2026 |
| Parameters | — | 2.8T |
| Multimodal | Yes | Yes |
| Context (input) | 256K | 1.0M |
| Context (output) | 64K | 1.0M |
| Input Price / 1M | $1.00 | $3.00 |
| Output Price / 1M | $4.00 | $15.00 |
| Average Score | 98.0% | 95.7% |
Verdict
Kimi K3 leads in 2 out of 4 comparison categories.
Both models show comparable average scores: GPT-5.1 Medium — 1.0, Kimi K3 — 1.0.
GPT-5.1 Medium is 3.6x cheaper: input $1.00/1M vs $3.00/1M tokens.
Kimi K3 supports a larger context: 1M vs 256K tokens.
Kimi K3 is newer: released 7/16/2026 vs 11/11/2025.
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Frequently Asked Questions
Which is better for coding — GPT-5.1 Medium or Kimi K3?
Which model is cheaper — GPT-5.1 Medium or Kimi K3?
Which has a larger context window — GPT-5.1 Medium or Kimi K3?
The GPT-5.1 Medium and Kimi K3 comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the GPT-5.1 Medium or Kimi K3 page. See also the complete list of AI model comparisons.