GPT-5.1 Codex High vs Step-3.5-Flash: Specs & Benchmark Comparison
| Characteristic | GPT-5.1 Codex High | Step-3.5-Flash |
|---|---|---|
| Company | OpenAI | StepFun |
| Release Date | November 11, 2025 | February 1, 2026 |
| Parameters | — | 196B |
| Multimodal | Yes | Yes |
| Context (input) | 400K | 66K |
| Context (output) | 128K | 8K |
| Input Price / 1M | $1.25 | $0.10 |
| Output Price / 1M | $10.00 | $0.40 |
| Average Score | 1.0 | 0.8 |
| Benchmarks | ||
| AIME 2025 | 1.0 | 1.0 |
Visual Benchmark Comparison
GPT-5.1 Codex High
Step-3.5-Flash
AIME 20251.0 vs 1.0
1.0
1.0
Verdict
Step-3.5-Flash leads in 2 out of 4 comparison categories.
Overall Performance
Both models show comparable average scores: GPT-5.1 Codex High — 1.0, Step-3.5-Flash — 0.8.
API Cost
Step-3.5-Flash is 22.5x cheaper: input $0.10/1M vs $1.25/1M tokens.
Context Window
GPT-5.1 Codex High supports a larger context: 400K vs 66K tokens.
Recency
Step-3.5-Flash is newer: released 2/1/2026 vs 11/11/2025.
More About These Models
Related Comparisons
The GPT-5.1 Codex High and Step-3.5-Flash 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 Codex High or Step-3.5-Flash page. See also the complete list of AI model comparisons.