High-volume, cost-sensitive work
Choose Kimi K3.1 Pro
Kimi K3.1 Pro costs 17% less on a typical mix of three input tokens for every output token ($4.00 against $4.81 per million tokens).
GPT-5.3-Codex vs Kimi K3.1 Pro: price, context and capabilities
Choose GPT-5.3-Codex for reused prompts and documents (RAG, agents). Choose Kimi K3.1 Pro for high-volume, cost-sensitive work, writing and code generation, very long inputs and the latest release.
In short
- Kimi K3.1 Pro is 17% cheaper than GPT-5.3-Codex at the headline price ($4.00 / 1M tokens vs $4.81 / 1M tokens).
- Kimi K3.1 Pro reads more per request: 1.05M tokens against 400k.
- Kimi K3.1 Pro is the newer model (Oct 23, 2026, against Feb 24, 2026).
- Only GPT-5.3-Codex offers batch api.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Kimi K3.1 Pro
Kimi K3.1 Pro charges $10.00 per million output tokens, against $14.00 for GPT-5.3-Codex. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose GPT-5.3-Codex
GPT-5.3-Codex charges $0.18 per million cached input tokens, against $0.20 for Kimi K3.1 Pro.
Very long inputs
Choose Kimi K3.1 Pro
Kimi K3.1 Pro reads up to 1.05M tokens per request, against 400k for GPT-5.3-Codex.
Latest release
Choose Kimi K3.1 Pro
Kimi K3.1 Pro is the newer release (Oct 23, 2026, against Feb 24, 2026 for GPT-5.3-Codex).
Monthly cost at three volumes
| Volume | GPT-5.3-Codex | Kimi K3.1 Pro | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $5.25 | $4.50 | Kimi K3.1 Pro, $0.75 less |
| Production: 20M input, 5M output tokens | $105.00 | $90.00 | Kimi K3.1 Pro, $15.00 less |
| Scale: 500M input, 100M output tokens | $2,275 | $2,000 | Kimi K3.1 Pro, $275.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| GPT-5.3-Codex | Kimi K3.1 Pro | |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Category | Language models | Language models |
| Status | Deprecated | Generally available |
| Headline price | $4.81 / 1M tokens | $4.00 / 1M tokens |
| Input | $1.75 / 1M tokens | $2.00 / 1M tokens |
| Output | $14.00 / 1M tokens | $10.00 / 1M tokens |
| Cached input | $0.175 / 1M tokens | $0.20 / 1M tokens |
| Context window | 400k | 1.05M |
| Max output | 128k | 944k |
| Released | Feb 24, 2026 | Oct 23, 2026 |
| Knowledge cutoff | August 2025 | No data |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching |
| API model id | gpt-5.3-codex | kimi-k3.1-pro |
Benchmarks side by side
Leader in bold.
| Benchmark | GPT-5.3-Codex | Kimi K3.1 Pro |
|---|---|---|
| Terminal-Bench Hard | 53% | No data |
| GPQA Diamond | 91.5% | No data |
| Humanity's Last Exam | 42.5% | No data |
| IFBench (instruction following) | 75.4% | No data |
| τ²-Bench (agentic tool use) | 86% | No data |
| MMMU-Pro (visual reasoning) | 78.5% | No data |
| Long-context reasoning (AA-LCR) | 83.3% | No data |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose GPT-5.3-Codex or Kimi K3.1 Pro?
Choose GPT-5.3-Codex for reused prompts and documents (RAG, agents). Choose Kimi K3.1 Pro for high-volume, cost-sensitive work, writing and code generation, very long inputs and the latest release.
Which is cheaper, GPT-5.3-Codex or Kimi K3.1 Pro?
Kimi K3.1 Pro is 17% cheaper than GPT-5.3-Codex at the headline price ($4.00 / 1M tokens vs $4.81 / 1M tokens).
Which has the larger context window, GPT-5.3-Codex or Kimi K3.1 Pro?
Kimi K3.1 Pro reads more per request: 1.05M tokens against 400k.
What is the difference between GPT-5.3-Codex and Kimi K3.1 Pro?
GPT-5.3-Codex is made by OpenAI and Kimi K3.1 Pro by Moonshot AI. Kimi K3.1 Pro is 17% cheaper than GPT-5.3-Codex at the headline price ($4.00 / 1M tokens vs $4.81 / 1M tokens). Kimi K3.1 Pro reads more per request: 1.05M tokens against 400k. Kimi K3.1 Pro is the newer model (Oct 23, 2026, against Feb 24, 2026). Only GPT-5.3-Codex offers batch api.
How much do GPT-5.3-Codex and Kimi K3.1 Pro cost per month?
At 20 million input and 5 million output tokens a month, GPT-5.3-Codex costs $105.00 and Kimi K3.1 Pro costs $90.00, at standard rates.
Which is newer, GPT-5.3-Codex or Kimi K3.1 Pro?
Kimi K3.1 Pro was released on Oct 23, 2026 and GPT-5.3-Codex on Feb 24, 2026.