Google Gemini 3.1 Pro vs xAI Grok 4.3: Live Promos, Pricing, Hidden Fees & Latency
Google Gemini 3.1 Pro (gemini-3.1-pro) — Google AI Startup Credits ($350K) & 90% Cache Promo
Google DeepMind is currently subsidizing Gemini 4 Argon at 50% off standard rates ($2.00/1M input & $10.00/1M output instead of $4/$20) until November 30, 2026, alongside 95% off Context Caching ($0.10/1M) and up to $350,000 in Google for Startups Cloud/Vertex AI credits.
xAI Grok 4.3 (grok-4.3) 2026 Q4 Developer Promotion & Volume Credits
Official 2026 Q4 promotion for xAI Grok 4.3: Activate ephemeral prefix caching to slash input costs by 84% (down to 0.2/1M) or route via asynchronous Batch API for 50% off standard token rates.
In Etuki October 2026 FinOps telemetry comparing Google Gemini 3.1 Pro (API ID: gemini-3.1-pro) vs xAI Grok 4.3 (API ID: grok-4.3), xAI Grok 4.3 offers lower standard input pricing at $1.25/1M tokens ($2.5/1M output), while Google Gemini 3.1 Pro leads in cached prefix economics at $0.2/1M tokens (90% discount). xAI Grok 4.3 achieves a 165ms faster P90 time-to-first-token latency (125ms vs 290ms).
Enable Prompt Context Caching & Batch API to reduce repeated system prompt input token burn by 50%-97.5%.
<200K: $1.25/$2.50 ($0.20 cache); >=200K full-request 2x cliff: $2.50/$5.00 ($0.40 cache). Batch discount is 20%; Priority tier 2x; US endpoint +10%.
| Specification / FinOps Dimension | Google Gemini 3.1 Pro | xAI Grok 4.3 | Verified Advantage |
|---|---|---|---|
| Official Vendor API ID | gemini-3.1-pro | grok-4.3 | Pinned Snapshot IDs |
| Standard Input / Output (per 1M) | $2 / $12 | $1.25 / $2.5 | xAI Grok 4.3 |
| Cache Read Price (per 1M) | $0.2/1M (90% Off) | $0.2/1M (84% Off) | Google Gemini 3.1 Pro |
| Context Window / Max Output | 2000K In / 128K Out | 1000K In / 128K Out | Google Gemini 3.1 Pro |
| P90 First-Token / Edge Latency | 290ms | 125ms | xAI Grok 4.3 (-165ms) |
Google 2M context multimodal model (<=200K: $2.00/$12.00, $0.20 cache; >200K cliff: $4.00/$18.00, 180K soft-block).
xAI Grok 4.3 high-speed reasoning model: $1.25/$2.50 (Cache $0.20/1M) short context; jumps to $2.50/$5.00 (Cache $0.40/1M) on long context.
Real-Time Stack Cost & Hidden-Fee Simulator (MAU / Token / Egress / GMV)
Calibrated with Reddit r/FinOps & r/devops telemetry: Includes Context Caching, Bandwidth Egress, and MoR Tax
✖️Switch from Google Gemini 3.1 Pro to xAI Grok 4.3
xAI Grok 4.3 high-speed reasoning model: $1.25/$2.50 (Cache $0.20/1M) short context; jumps to $2.50/$5.00 (Cache $0.40/1M) on long context. Verified P90 latency of 125ms.