GPT-5.1 Medium vs Step-3.5-Flash
GPT-5.1 Medium and Step-3.5-Flash are closely matched at 31.2 and 37.1 on the LLM Stats Score. Step-3.5-Flash is 19.6x cheaper per token.
OpenAI · StepFun · Updated for 2026
Which is better?
GPT-5.1 Medium and Step-3.5-Flash are closely matched on the overall LLM Stats Score at 31.2 and 37.1.
In the 1 individual benchmarks reported for both models, GPT-5.1 Medium wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, Step-3.5-Flash is roughly 19.6x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.1 Medium also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.1 Medium
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- you process long inputs — it offers a 400,000 token context window
Choose Step-3.5-Flash
- cost matters — it's about 19.6x cheaper per token
- you want the most recent training data — it shipped Feb 2026
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Individual benchmarks
1 reported for GPT-5.1 Medium · 7 for Step-3.5-Flash
GPT-5.1 Medium outperforms in 1 benchmarks (AIME 2025), while Step-3.5-Flash is better at 0 benchmarks.
GPT-5.1 Medium significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.1 Medium ($1.25/1M tokens) is 12.5x more expensive than Step-3.5-Flash ($0.10/1M tokens).
For output processing, GPT-5.1 Medium ($10.00/1M tokens) is 25.0x more expensive than Step-3.5-Flash ($0.40/1M tokens).
In conclusion, GPT-5.1 Medium is more expensive than Step-3.5-Flash.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.1 Medium accepts 400,000 input tokens compared to Step-3.5-Flash's 65,536 tokens. GPT-5.1 Medium can generate longer responses up to 128,000 tokens, while Step-3.5-Flash is limited to 8,192 tokens.
Input capabilities
Documented input modalities across available providers
GPT-5.1 Medium supports multimodal inputs, whereas Step-3.5-Flash does not.
GPT-5.1 Medium can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.1 Medium
Step-3.5-Flash
License
Usage and distribution terms
GPT-5.1 Medium is licensed under a proprietary license, while Step-3.5-Flash uses Apache 2.0.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Apache 2.0
Open weights
Release Timeline
When each model was launched
GPT-5.1 Medium was released on 2025-11-12, while Step-3.5-Flash was released on 2026-02-02.
Step-3.5-Flash is 3 months newer than GPT-5.1 Medium.
Nov 12, 2025
11 months ago
Feb 2, 2026
8 months ago
2mo newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
GPT-5.1 Medium is available from OpenAI. Step-3.5-Flash is available from StepFun.
GPT-5.1 Medium
Step-3.5-Flash
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.1 Medium and Step-3.5-Flash side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.1 Medium vs Step-3.5-Flash.