Compare / head-to-head
Grok 4 Fast Reasoningvso3
Grok 4 Fast Reasoning leads 2 of 2 shared benchmarks. Grok 4 Fast Reasoning is 14.3x cheaper per token. Grok 4 Fast Reasoning has the larger context window (2M tokens).
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
2 – 0
Grok 4 Fast Reasoning leads
Cheaper per token
Grok 4 Fast Reasoning
14.3x cheaper, input + output
Larger context
Grok 4 Fast Reasoning
2M tokens
Provider uptime (30d)
— · 94.9843%
xAI · OpenAI
Grok 4 Fast Reasoning
xAI · released 2025-09-19
text
Quality
Benchmark matrix
2 shared · 10 only Grok 4 Fast Reasoning · 5 only o3| Benchmark | Grok 4 Fast Reasoning | o3 | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 2 | ||||
| GPQA Diamond | 85.7% ↗ | 81.8% ↗epoch | +3.9 pt | Grok 4 Fast Reasoning |
| AIME 2025 | 92% ↗ | 89.2% ↗matharena ⚠ | +2.8 pt | Grok 4 Fast Reasoning |
| Only Grok 4 Fast Reasoning reports · 10 | ||||
| Humanity's Last Exam (no tools) | 20% ↗ | not reported | — | — |
| BrowseComp | 44.9% ↗ | not reported | — | — |
| BrowseComp (zh) | 51.2% ↗ | not reported | — | — |
| HMMT 2025 (no tools) | 93.3% ↗ | not reported | — | — |
| LiveCodeBench (Jan-May) | 80% ↗ | not reported | — | — |
| Reka Research Eval | 66% ↗ | not reported | — | — |
| Search Arena Elo | 1163 ↗ | not reported | — | — |
| SimpleQA | 95% ↗ | not reported | — | — |
| X Bench Deepsearch (zh) | 74% ↗ | not reported | — | — |
| X Browse | 58% ↗ | not reported | — | — |
| Only o3 reports · 5 | ||||
| SWE-bench Verified | not reported | 69.1% ↗ | — | — |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | not reported | 33.3% ↗epoch | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | not reported | 84.4% ↗epoch | — | — |
| SimpleQA Verified | not reported | 49.4% ↗epoch | — | — |
| SWE-bench Verified (Epoch AI run) | not reported | 62.3% ↗epoch | — | — |
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 Grok 4 Fast Reasoning minus o3 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 | Grok 4 Fast Reasoning | o3 | Edge |
|---|---|---|---|
| Context window | 2M tokens | 200K tokens | Grok 4 Fast Reasoning |
| Max output | — | 100K tokens | — |
| Input price / 1M | $0.2 ↗ | $2 ↗ | Grok 4 Fast Reasoning |
| Output price / 1M | $0.5 ↗ | $8 ↗ | Grok 4 Fast Reasoning |
| Cached input / 1M | $0.05 ↗ | $0.5 ↗ | Grok 4 Fast Reasoning |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $0.7 | $10 | Grok 4 Fast Reasoning |
| Modalities | text | text · vision | o3 |
| Released | 2025-09-19 | 2025-04-16 | — |
| Cited benchmark scores | 12 | 7 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
Grok 4 Fast Reasoning vs …
Models sharing the most benchmarksMore matchups
o3 vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run Grok 4 Fast Reasoning and o3 on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.