Compare / head-to-head
Gemini 3.8 Flashvs
Grok 4.1 Fast Reasoning
Gemini 3.8 Flash leads 5 of 5 shared benchmarks. Grok 4.1 Fast Reasoning is 6.4x cheaper per token. Grok 4.1 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
5 – 0
Gemini 3.8 Flash leads
Cheaper per token
Grok 4.1 Fast Reasoning
6.4x cheaper, input + output
Larger context
Grok 4.1 Fast Reasoning
2M tokens
Providers
2 providers
Google · xAI
Gemini 3.8 Flash
Google · released 2026-09-02
textvisionaudio
Grok 4.1 Fast Reasoning
xAI · released 2025-11-19
text
Quality
Benchmark matrix
5 shared · 32 only Gemini 3.8 Flash · 2 only Grok 4.1 Fast Reasoning| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast Reasoning | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 5 | ||||
| LMArena Elo | 1494.8 ↗ | 1430.3 ↗ | +64.5 | Gemini 3.8 Flash |
| LMArena Vision (LMArena) | 1290.3 ↗ | 1196.3 ↗ | +94 | Gemini 3.8 Flash |
| LMArena WebDev (LMArena) | 1582.7 ↗ | 1241.3 ↗ | +341.4 | Gemini 3.8 Flash |
| SAGE (Vals AI) | 35.1% ↗ | 31.3% ↗ | +3.8 pt | Gemini 3.8 Flash |
| Vending-Bench 2 (Andon Labs) | 5093.79 ↗ | 1106.63 ↗ | +3987.2 | Gemini 3.8 Flash |
| Only Gemini 3.8 Flash reports · 32 | ||||
| GPQA Diamond | 95.3% ↗ | not reported | — | — |
| APEX-Agents (Mercor) | 64.3% ↗ | not reported | — | — |
| CharXiv Reasoning (no tools) | 86.2% ↗ | not reported | — | — |
| Chess Puzzles (Epoch AI run) | 61% ↗epoch run | not reported | — | — |
| DeepSWE v1.1 | 73.7% ↗ | not reported | — | — |
| DeepSWE v1.1 (Datacurve) | 73.8% ↗ | not reported | — | — |
| FrontierMath Tier 4 v2 (Epoch AI run) | 22% ↗epoch run | not reported | — | — |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 68.4% ↗epoch run | not reported | — | — |
| FrontierSWE V2 (Proximal Labs) | 19.6% ↗ | not reported | — | — |
| Furniture Assembly (Epoch AI run) | 31.7% ↗epoch run | not reported | — | — |
| GDPVal-AA v2 | 1545 ↗ | not reported | — | — |
| Harvey's Legal Agent Benchmark | 10% ↗ | not reported | — | — |
| HLE-Verified | 54.9% ↗ | not reported | — | — |
| LABBench2 | 86.2% ↗ | not reported | — | — |
| LiveBench Agentic Coding (LiveBench) | 54.2% ↗ | not reported | — | — |
| LiveBench Coding (LiveBench) | 72.5% ↗ | not reported | — | — |
| LiveBench Data Analysis (LiveBench) | 54% ↗ | not reported | — | — |
| LiveBench Instruction Following (LiveBench) | 81.4% ↗ | not reported | — | — |
| LiveBench Language (LiveBench) | 87.8% ↗ | not reported | — | — |
| LiveBench Mathematics (LiveBench) | 91.6% ↗ | not reported | — | — |
| LiveBench Reasoning (LiveBench) | 89.3% ↗ | not reported | — | — |
| LMArena Agent (LMArena) | 0.0297 ↗ | not reported | — | — |
| Mystery Game Puzzles (Epoch AI run) | 47% ↗epoch run | not reported | — | — |
| OSWorld-2.0 | 59% ↗ | not reported | — | — |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 98.9% ↗epoch run | not reported | — | — |
| SimpleBench (SimpleBench) | 82.4% ↗ | not reported | — | — |
| SimpleQA Verified | 69.7% ↗epoch run | not reported | — | — |
| Terminal-bench 2.1 | 89.4% ↗ | not reported | — | — |
| Terminal-bench 4.0 | 19.1% ↗ | not reported | — | — |
| Terminal-Bench 4.0 (Vals AI) | 19.2% ↗ | not reported | — | — |
| Vals Finance Agent v2 | 61.4% ↗ | not reported | — | — |
| WeirdML (Håvard Tveit Ihle) | 84.8% ↗ | not reported | — | — |
| Only Grok 4.1 Fast Reasoning reports · 2 | ||||
| FRAMES (Agent Tools API) | not reported | 87.6% ↗ | — | — |
| Research-Eval Reka (Agent Tools API) | not reported | 63.9% ↗ | — | — |
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 3.8 Flash minus Grok 4.1 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 3.8 Flash | Grok 4.1 Fast Reasoning | Edge |
|---|---|---|---|
| Context window | 1.0M tokens | 2M tokens | Grok 4.1 Fast Reasoning |
| Max output | 66K tokens | — | — |
| Input price / 1M | $0.75 ↗ | $0.2 ↗ | Grok 4.1 Fast Reasoning |
| Output price / 1M | $3.75 ↗ | $0.5 ↗ | Grok 4.1 Fast Reasoning |
| Cached input / 1M | $0.075 ↗ | $0.05 ↗ | Grok 4.1 Fast Reasoning |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $4.5 | $0.7 | Grok 4.1 Fast Reasoning |
| Modalities | text · vision · audio | text | Gemini 3.8 Flash |
| Released | 2026-09-02 | 2025-11-19 | — |
| Cited benchmark scores | 43 | 7 | — |
Reliability
Provider status
Live from /statusMore matchups
Gemini 3.8 Flash vs …
Models sharing the most benchmarksMore matchups
Grok 4.1 Fast Reasoning vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run Gemini 3.8 Flash and Grok 4.1 Fast Reasoning on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.