Compare / head-to-head
Gemini 2.5 FlashvsGrok 4 Fast Reasoning
Grok 4 Fast Reasoning leads 3 of 3 shared benchmarks. Grok 4 Fast Reasoning is 4x 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
0 – 3
Grok 4 Fast Reasoning leads
Cheaper per token
Grok 4 Fast Reasoning
4x cheaper, input + output
Larger context
Grok 4 Fast Reasoning
2M tokens
Provider uptime (30d)
100% · —
Google · xAI
Gemini 2.5 Flash
Google · released 2025-06-17
textvisionaudio
Grok 4 Fast Reasoning
xAI · released 2025-09-19
text
Quality
Benchmark matrix
3 shared · 5 only Gemini 2.5 Flash · 9 only Grok 4 Fast Reasoning| Benchmark | Gemini 2.5 Flash | Grok 4 Fast Reasoning | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 3 | ||||
| GPQA Diamond | 82.8% ↗ | 85.7% ↗ | -2.9 pt | Grok 4 Fast Reasoning |
| AIME 2025 | 72% ↗ | 92% ↗ | -20 pt | Grok 4 Fast Reasoning |
| Humanity's Last Exam (no tools) | 11% ↗ | 20% ↗ | -9 pt | Grok 4 Fast Reasoning |
| Only Gemini 2.5 Flash reports · 5 | ||||
| SWE-bench Verified | 48.9% ↗ | not reported | — | — |
| LMArena Elo | 1417.3 ↗ | not reported | — | — |
| Aider Polyglot | 56.7% ↗ | not reported | — | — |
| LiveCodeBench | 59.3% ↗ | not reported | — | — |
| MMMU | 79.7% ↗ | not reported | — | — |
| Only Grok 4 Fast Reasoning reports · 9 | ||||
| BrowseComp | not reported | 44.9% ↗ | — | — |
| BrowseComp (zh) | not reported | 51.2% ↗ | — | — |
| HMMT 2025 (no tools) | not reported | 93.3% ↗ | — | — |
| LiveCodeBench (Jan-May) | not reported | 80% ↗ | — | — |
| Reka Research Eval | not reported | 66% ↗ | — | — |
| Search Arena Elo | not reported | 1163 ↗ | — | — |
| SimpleQA | not reported | 95% ↗ | — | — |
| X Bench Deepsearch (zh) | not reported | 74% ↗ | — | — |
| X Browse | not reported | 58% ↗ | — | — |
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 Gemini 2.5 Flash minus Grok 4 Fast Reasoning 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 | Gemini 2.5 Flash | Grok 4 Fast Reasoning | Edge |
|---|---|---|---|
| Context window | 1.0M tokens | 2M tokens | Grok 4 Fast Reasoning |
| Max output | 66K tokens | — | — |
| Input price / 1M | $0.3 ↗ | $0.2 ↗ | Grok 4 Fast Reasoning |
| Output price / 1M | $2.5 ↗ | $0.5 ↗ | Grok 4 Fast Reasoning |
| Cached input / 1M | $0.03 ↗ | $0.05 ↗ | Gemini 2.5 Flash |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $2.8 | $0.7 | Grok 4 Fast Reasoning |
| Modalities | text · vision · audio | text | Gemini 2.5 Flash |
| Released | 2025-06-17 | 2025-09-19 | — |
| Cited benchmark scores | 9 | 12 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
Gemini 2.5 Flash vs …
Models sharing the most benchmarksMore matchups
Grok 4 Fast Reasoning vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run Gemini 2.5 Flash and Grok 4 Fast Reasoning on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.