Gemini 3.8 Flash vs Grok 4.3
Side-by-side comparison of API pricing, specs, benchmarks, and capabilities
| Specification |
Gemini 3.8 FlashIntro price
by Google
|
by xAI
|
|---|---|---|
| Overview | ||
| Status | Current flagship | Current flagship |
| Released | ||
| Pricing per million tokens | ||
| Input | $0.750/Mtok | $1.25/Mtok |
| Output | $3.75/Mtok | $2.50/Mtok |
| Blended avg | $1.50/Mtok | $1.56/Mtok |
| Cached input | $0.075/Mtok | $0.200/Mtok |
| Price basis | Google's Gemini API pricing page prints a dated, two-phase schedule for this model, the same Standard tier as Gemini 3.7 Flash: $0.75 per 1M input tokens through December 31, 2026, rising to $1.50 on January 1, 2027, and $3.75 per 1M output tokens through December 31, 2026, rising to $7.50. Context caching follows the same dates ($0.075, then $0.15). We publish the rate you would pay today and re-verify it before the changeover date. Note that resellers may quote a lower figure: OpenRouter's ':batch' route for this model shows $0.375/$1.875, which is Google's own Batch tier — exactly half the standard rate, and not what an ordinary API call is billed. We publish the standard rate. Checked 2026-09-03 against ai.google.dev/gemini-api/docs/pricing, anchored on the section's API-name line 'Gemini 3.8 Flash gemini-3.8-flash'. | — |
| Specifications | ||
| Context window | 1M tokens | 1M tokens |
| Parameters | Proprietary | Proprietary |
| Speed (TPS) | — | — |
| Modalities | ||
| Input |
textimageaudiovideo
|
textimage
|
| Benchmarks sources: Artificial Analysis / xAI model card, Artificial Analysis | ||
| Independent composite scores measured for both models — each on its own scale | ||
| AA Intelligence Index | 58.7 | 37.9 |
| AA Agentic Index | 50 | 24.2 |
| AA-Omniscience Index (−100–100) | 29.6 | 18 |
| LMSYS Chatbot Arena | 1493.8 ELO | 1443 ELO |
| GDPval-AA v2 | 1545.5 ELO | — |
| Per-benchmark results published for Grok 4.3 only — no independent per-benchmark scores exist for Gemini 3.8 Flash yet | ||
| Avg benchmark score | — | 72.4 |
| Perf / dollar | — | 46.3 |
| GPQA Diamond | — | 80 |
| SWE-Bench Verified | — | 65 |
| Humanity's Last Exam | — | 38 |
| ARC-AGI 2 | — | 42 |
| AIME 2025 | — | 85 |
| MMMLU | — | 86 |
| BFCL | — | 78 |
| HumanEval | — | 90 |
| MATH 500 | — | 88 |
| Providers | ||
| Available from |
Google — $0.750/$3.75/Mtok
|
xAI — $1.25/$2.50/Mtok
|
Cost at scale
1M tokens · 50/50 input/output| Volume | Gemini 3.8 Flash | Grok 4.3 | Savings |
|---|---|---|---|
| 1M tokens | $1.5 | $1.56 | $0.06 (3.8%) |
| 10M tokens | $15 | $15.63 | $0.63 (4%) |
| 100M tokens | $150 | $156.25 | $6.25 (4%) |
| 1000M tokens | $1500 | $1562.5 | $62.5 (4%) |
When to pick which
distilled from the pricing and spec data above- cost dominates: $1.50/Mtok blended vs $1.56 — 4% less on the same 50/50 token mix
- your workload re-reads context (agents, RAG, long chats): cached input costs $0.075/Mtok — 90% off its list input price
- this pairing gives Grok 4.3 no edge on price, context, cache discount, or measured performance — pick it only for qualitative fit (ecosystem, compliance, model behavior on your prompts)
The cheaper option here — Gemini 3.8 Flash costs $1.50/Mtok blended on Google.
Summary
Gemini 3.8 Flash by Google costs $0.750/Mtok input and $3.75/Mtok output, with a 1M-token context window. It supports text, image, audio, video input.
Grok 4.3 by xAI costs $1.25/Mtok input and $2.50/Mtok output, with a 1M-token context window. It supports text, image input.
On a blended cost basis, Gemini 3.8 Flash is 4% cheaper than Grok 4.3.
The two aren't directly comparable on average benchmark score: Grok 4.3 has published per-benchmark results, while Gemini 3.8 Flash 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.