Grok 4.1 Fast vs Gemini 2.5 Flash
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
by xAI
|
by Google
|
|---|---|---|
| Overview | ||
| Status | Retired budget | Deprecated budget |
| Released | Sep 22, 2025 | Jun 17, 2025 |
| Pricing per million tokens | ||
| Input | $0.200/Mtok | $0.300/Mtok |
| Output | $0.500/Mtok | $2.50/Mtok |
| Blended avg | $0.275/Mtok | $0.850/Mtok |
| Specifications | ||
| Context window | 2M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimage
|
textimageaudiovideo
|
| Benchmarks sources: xAI model card / Vellum LLM Leaderboard | ||
| GPQA Diamond | 62 vendor | 78.3 |
| SWE-Bench Verified | 40 vendor | 38 |
| Humanity's Last Exam | 20 vendor | 12.1 |
| ARC-AGI 2 | 25 vendor | 15 |
| AIME 2025 | 65 vendor | 78 |
| MMMLU | 78 vendor | 78 |
| MATH 500 | 72 vendor | 72 |
| Avg benchmark score | — | 50.2 |
| Perf / dollar | — | 59.1 |
| Terminal-Bench 2.1 | — | 16.9 |
| LiveCodeBench | — | 63.5 |
| BFCL | 68 vendor | — |
| HumanEval | 83 vendor | — |
| Independent composite scores each on its own scale — not part of the average above | ||
| LMSYS Chatbot Arena | 1430.7 ELO | 1410.2 ELO |
| Providers | ||
| Available from |
xAI — $0.200/$0.500/Mtok
|
Google — $0.300/$2.50/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Grok 4.1 Fast | Gemini 2.5 Flash | Savings |
|---|---|---|---|
| 1M tokens | $0.28 | $0.85 | $0.57 (67.1%) |
| 10M tokens | $2.75 | $8.5 | $5.75 (67.6%) |
| 100M tokens | $27.5 | $85 | $57.5 (67.6%) |
| 1000M tokens | $275 | $850 | $575 (67.6%) |
When to pick which
distilled from the pricing and spec data above- cost dominates: $0.275/Mtok blended vs $0.850 — 67.6% less on the same 50/50 token mix
- you need the longer context: 2M tokens vs 1M (2×)
- this pairing gives Gemini 2.5 Flash no edge on price, context, cache discount, or measured performance — pick it only for qualitative fit (ecosystem, compliance, model behavior on your prompts)
Price movement
recorded changes since we began tracking each model · last checked Aug 15, 2026| Model | Changes | Latest move | Old → new $/M |
|---|---|---|---|
| Grok 4.1 Fast | 0 | — no move | Stable since we began tracking — no change recorded |
| Gemini 2.5 Flash | 2 | price rise on Jul 4, 2026 | $0.075/$0.3 → $0.3/$2.5/Mtok |
The cheaper option here — Grok 4.1 Fast costs $0.275/Mtok blended on xAI.
Summary
Grok 4.1 Fast by xAI costs $0.200/Mtok input and $0.500/Mtok output, with a 2M-token context window. It supports text, image input.
Gemini 2.5 Flash by Google costs $0.300/Mtok input and $2.50/Mtok output, with a 1M-token context window. It supports text, image, audio, video input.
On a blended cost basis, Grok 4.1 Fast is 67.6% cheaper than Gemini 2.5 Flash.It also has a larger context window.
The two aren't directly comparable on average benchmark score: Gemini 2.5 Flash has published per-benchmark results, while Grok 4.1 Fast does not yet — it is measured today on independent composites (see the table above).
Note: Pricing is per million tokens. Actual costs vary with usage patterns, prompt caching, and batch discounts. Always verify against official provider pricing pages.