Key Takeaways
GPT-5.2 Pro wins:
- Larger context window
- Faster response time
- Higher intelligence benchmark
- Better at coding
- Better at math
- Supports vision
- Supports tool calls
Step 3.5 Flash wins:
- Cheaper input tokens
- Cheaper output tokens
Price Advantage
Step 3.5 Flash
Benchmark Advantage
GPT-5.2 Pro
Context Window
GPT-5.2 Pro
Speed
GPT-5.2 Pro
Pricing Comparison
Price Comparison
| Metric | GPT-5.2 Pro | Step 3.5 Flash | Winner |
|---|---|---|---|
| Input (per 1M tokens) | $21.00 | $0.10 | Step 3.5 Flash |
| Output (per 1M tokens) | $168.00 | $0.30 | Step 3.5 Flash |
| Cache Read (per 1M) | N/A | $20000.00 | Step 3.5 Flash |
Using a 3:1 input/output ratio, Step 3.5 Flash is 100% cheaper overall.
GPT-5.2 Pro Providers
OpenAI $21.00 (Cheapest)
Step 3.5 Flash Providers
No provider data available
Benchmark Comparison
6
Benchmarks Compared
0
GPT-5.2 Pro Wins
0
Step 3.5 Flash Wins
Benchmark Scores
| Benchmark | GPT-5.2 Pro | Step 3.5 Flash | Winner |
|---|---|---|---|
Intelligence Index Overall intelligence score | 51.2 | - | - |
Coding Index Code generation & understanding | 48.7 | - | - |
Math Index Mathematical reasoning | 99.0 | - | - |
MMLU Pro Academic knowledge | 87.4 | - | - |
GPQA Graduate-level science | 90.3 | - | - |
LiveCodeBench Competitive programming | 88.9 | - | - |
GPT-5.2 Pro significantly outperforms in coding benchmarks.
Cost vs Quality
X-axis:
Y-axis:
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GPT-5.2 Pro
Other models
Context & Performance
Context Window
GPT-5.2 Pro
400,000
tokens
Max output: 128,000 tokens
Step 3.5 Flash
256,000
tokens
Max output: 256,000 tokens
GPT-5.2 Pro has a 36% larger context window.
Speed Performance
| Metric | GPT-5.2 Pro | Step 3.5 Flash | Winner |
|---|---|---|---|
| Tokens/second | 99.2 tok/s | N/A | |
| Time to First Token | 48.04s | N/A |
Capabilities
Feature Comparison
| Feature | GPT-5.2 Pro | Step 3.5 Flash |
|---|---|---|
| Vision (Image Input) | ||
| Tool/Function Calls | ||
| Reasoning Mode | ||
| Audio Input | ||
| Audio Output | ||
| PDF Input | ||
| Prompt Caching | ||
| Web Search |
License & Release
| Property | GPT-5.2 Pro | Step 3.5 Flash |
|---|---|---|
| License | Proprietary | Proprietary |
| Author | OpenAI | Stepfun-ai |
| Released | Dec 2025 | Jan 2026 |
GPT-5.2 Pro Modalities
Input
imagetextfile
Output
text
Step 3.5 Flash Modalities
Input
text
Output
text