Compare / head-to-head
GPT-5.5vsStep 3.5 Flash
GPT-5.5 leads 4 of 4 shared benchmarks. GPT-5.5 has the larger context window (1M tokens).
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
4 – 0
GPT-5.5 leads
Cheaper per token
—
list price, input + output
Larger context
GPT-5.5
1M tokens
Provider uptime (30d)
95.1952% · —
OpenAI · StepFun
GPT-5.5
OpenAI · released 2026-04-23
textvision
Step 3.5 Flash
StepFun · released 2026-02-12
text
- Context
- 256K
- Max out
- —
- Input /1M
- —
- Output /1M
- —
- Cached /1M
- —
- Scores
- 18 · 5 core
Quality
Benchmark matrix
4 shared · 17 only GPT-5.5 · 13 only Step 3.5 Flash| Benchmark | GPT-5.5 | Step 3.5 Flash | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 4 | ||||
| AIME 2026 | 100% ↗matharena ⚠ | 96.7% ↗matharena | +3.3 pt | GPT-5.5 |
| LMArena Elo | 1465.6 ↗ | 1403.7 ↗ | +61.9 | GPT-5.5 |
| BrowseComp | 84.4% ↗ | 51.6% ↗ | +32.8 pt | GPT-5.5 |
| Terminal-Bench 2.0 | 82.7% ↗ | 51% ↗ | +31.7 pt | GPT-5.5 |
| Only GPT-5.5 reports · 17 | ||||
| GPQA Diamond | 90.7% ↗epoch | not reported | — | — |
| ARC-AGI-1 (Verified) | 95% ↗ | not reported | — | — |
| ARC-AGI-2 (Verified) | 85% ↗ | not reported | — | — |
| FrontierMath Tier 1-3 | 51.7% ↗ | not reported | — | — |
| FrontierMath Tier 4 | 35.4% ↗ | not reported | — | — |
| FrontierMath Tier 4 v2 (Epoch AI run) | 72.5% ↗epoch | not reported | — | — |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 85.3% ↗epoch | not reported | — | — |
| GDPval (wins or ties) | 84.9% ↗ | not reported | — | — |
| MCP Atlas | 75.3% ↗ | not reported | — | — |
| MMMU-Pro (no tools) | 81.2% ↗ | not reported | — | — |
| MMMU-Pro (with tools) | 83.2% ↗ | not reported | — | — |
| OSWorld-Verified | 78.7% ↗ | not reported | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 84.4% ↗epoch | not reported | — | — |
| SimpleQA Verified | 63% ↗epoch | not reported | — | — |
| SWE-Bench Pro | 58.6% ↗ | not reported | — | — |
| Tau2-bench Telecom | 98% ↗ | not reported | — | — |
| Toolathlon | 55.6% ↗ | not reported | — | — |
| Only Step 3.5 Flash reports · 13 | ||||
| SWE-bench Verified | not reported | 74.4% ↗ | — | — |
| AIME 2025 | not reported | 97.3% ↗ | — | — |
| BrowseComp (with context manager) | not reported | 69% ↗ | — | — |
| BrowseComp-ZH | not reported | 66.9% ↗ | — | — |
| BrowseComp-ZH (with context manager) | not reported | 73.7% ↗ | — | — |
| GAIA (no file) | not reported | 84.5% ↗ | — | — |
| HMMT 2025 (Feb/Nov average) | not reported | 96.2% ↗ | — | — |
| IMOAnswerBench | not reported | 85.4% ↗ | — | — |
| LiveCodeBench v6 | not reported | 86.4% ↗ | — | — |
| ResearchRubrics | not reported | 65.3% ↗ | — | — |
| Tau2-Bench | not reported | 88.2% ↗ | — | — |
| xbench-DeepSearch 2025.05 | not reported | 83.7% ↗ | — | — |
| xbench-DeepSearch 2025.10 | not reported | 56.3% ↗ | — | — |
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is GPT-5.5 minus Step 3.5 Flash in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | GPT-5.5 | Step 3.5 Flash | Edge |
|---|---|---|---|
| Context window | 1M tokens | 256K tokens | GPT-5.5 |
| Max output | 128K tokens | — | — |
| Input price / 1M | $5 ↗ | — | — |
| Output price / 1M | $30 ↗ | — | — |
| Cached input / 1M | $0.5 ↗ | — | — |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $35 | — | — |
| Modalities | text · vision | text | GPT-5.5 |
| Released | 2026-04-23 | 2026-02-12 | — |
| Cited benchmark scores | 21 | 18 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
GPT-5.5 vs …
Models sharing the most benchmarksMore matchups
Step 3.5 Flash vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run GPT-5.5 and Step 3.5 Flash on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.