Compare / head-to-head
GPT-5.5vsSeed2.1 Pro
GPT-5.5 leads 1 of 1 shared benchmark.
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
1 – 0
GPT-5.5 leads
Cheaper per token
—
list price, input + output
Larger context
—
both 1M tokens
Provider uptime (30d)
94.2446% · —
OpenAI · ByteDance Seed
GPT-5.5
OpenAI · released 2026-04-23
textvision
Seed2.1 Pro
ByteDance Seed · released 2026-07-13
textvisionvideo
- Context
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- Max out
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- Input /1M
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- Output /1M
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- Cached /1M
- —
- Scores
- 26 · 2 core
Quality
Benchmark matrix
1 shared · 20 only GPT-5.5 · 25 only Seed2.1 Pro| Benchmark | GPT-5.5 | Seed2.1 Pro | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 1 | ||||
| MMMU-Pro (with tools) | 83.2% ↗ | 82.7% ↗ | +0.5 pt | GPT-5.5 |
| Only GPT-5.5 reports · 20 | ||||
| GPQA Diamond | 90.7% ↗epoch | not reported | — | — |
| AIME 2026 | 100% ↗matharena ⚠ | not reported | — | — |
| LMArena Elo | 1465.6 ↗ | not reported | — | — |
| ARC-AGI-1 (Verified) | 95% ↗ | not reported | — | — |
| ARC-AGI-2 (Verified) | 85% ↗ | not reported | — | — |
| BrowseComp | 84.4% ↗ | 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 | — | — |
| 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 | — | — |
| Terminal-Bench 2.0 | 82.7% ↗ | not reported | — | — |
| Toolathlon | 55.6% ↗ | not reported | — | — |
| Only Seed2.1 Pro reports · 25 | ||||
| Agent Startup Bench | not reported | 68.8% ↗ | — | — |
| BabyVision | not reported | 73.7% ↗ | — | — |
| BeyondAIME | not reported | 87% ↗ | — | — |
| CharXiv-RQ | not reported | 85.4% ↗ | — | — |
| CharXiv-RQ (with tools) | not reported | 86.4% ↗ | — | — |
| ERQA | not reported | 72% ↗ | — | — |
| KINA | not reported | 48.3% ↗ | — | — |
| MathVision | not reported | 92.6% ↗ | — | — |
| MathVision (with tools) | not reported | 94.5% ↗ | — | — |
| Minerva Video Reasoning | not reported | 70.7% ↗ | — | — |
| MMLongBench 128K | not reported | 78.3% ↗ | — | — |
| MMMU-Pro | not reported | 81.6% ↗ | — | — |
| NL2Repo-Bench | not reported | 47% ↗ | — | — |
| OVOBench | not reported | 80.7% ↗ | — | — |
| SuperGPQA | not reported | 70.8% ↗ | — | — |
| SWE-Atlas | not reported | 35.2% ↗ | — | — |
| Terminal-Bench 2.1 | not reported | 71% ↗ | — | — |
| TOMATO | not reported | 79.5% ↗ | — | — |
| VideoMME | not reported | 89.2% ↗ | — | — |
| VideoSimpleQA | not reported | 76.4% ↗ | — | — |
| Workspace Bench | not reported | 53% ↗ | — | — |
| WorldVQA | not reported | 53% ↗ | — | — |
| xDailyBench | not reported | 61% ↗ | — | — |
| ZEROBench | not reported | 18% ↗ | — | — |
| ZEROBench (with tools) | not reported | 22% ↗ | — | — |
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 Seed2.1 Pro 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 | Seed2.1 Pro | Edge |
|---|---|---|---|
| Context window | 1M tokens | — | — |
| 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 · vision · video | Seed2.1 Pro |
| Released | 2026-04-23 | 2026-07-13 | — |
| Cited benchmark scores | 21 | 26 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
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Which one wins on your data?
Public benchmarks are a starting point. Run GPT-5.5 and Seed2.1 Pro on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.