Which is cheaper: Grok 4.5 or Gemini 3.1 Pro?

Grok 4.5 is cheaper on output tokens: $2 input / $6 output per MTok vs Gemini 3.1 Pro's $2 input / $12 output per MTok. For a typical 30K-input / 5K-output coding task, Grok 4.5 costs $0.09 vs Gemini 3.1 Pro's $0.12 — a 25% saving. On input-heavy workloads (RAG, long documents), the two are effectively equal on input pricing.

Which is better for coding: Grok 4.5 or Gemini 3.1 Pro?

Grok 4.5 leads on coding-specific benchmarks: 62.0% on DeepSWE 1.0 and 83.3% on Terminal-Bench 2.1. Gemini 3.1 Pro leads on ARC-AGI-2 (~77%) and long-context recall (~90% MRCR-v2 at 1M tokens). Grok 4.5 was co-trained with Cursor coding data, giving it an edge on real-world IDE workflows. For pure code generation and terminal agents, Grok 4.5 wins.

Which has the bigger context window?

Gemini 3.1 Pro at 1M tokens (extending to 2M for select customers). Grok 4.5 offers 500K tokens. For document-heavy workloads (legal review, book-length analysis, whole-repo context), Gemini 3.1 Pro's 1M+ window is a decisive advantage, especially given its strong ~90% MRCR-v2 recall at 1M.

Is Gemini 3.1 Pro multimodal? Is Grok 4.5?

Gemini 3.1 Pro is natively multimodal — text, image, audio, and video in a single model. Grok 4.5 is primarily text-focused with image input support. If your workflow requires video understanding, audio transcription, or heavy multimodal reasoning, Gemini 3.1 Pro is the clear pick.

Quick Answer

Grok 4.5 vs Gemini 3.1 Pro: The Cheap Frontier Showdown (July 2026)

Published: July 10, 2026

Two Cheap Frontier Models, One Choice

July 2026 gave us two models that broke the frontier price ceiling:

Grok 4.5 (launched July 8, 2026) at $2 / $6 per MTok
Gemini 3.1 Pro (released February 19, 2026) at $2 / $12 per MTok

Both sit near the top of major benchmarks. Both cost a fraction of Claude Opus 4.8 ($15/$75) or GPT-5.6 Sol Ultra ($12.50/$75). If you’re building a production AI stack and need to pick one as your default, here’s the head-to-head.

Head-to-Head Specs

Feature	Grok 4.5	Gemini 3.1 Pro
Provider	SpaceXAI	Google DeepMind
Launch	July 8, 2026	February 19, 2026
Input / MTok	$2.00	$2.00
Output / MTok	$6.00	$12.00
Context window	500K	1M (2M select)
Multimodal	Text + image	Text + image + audio + video
Serving speed	~80 tok/s	~60-90 tok/s (varies)
Best for	Coding, agentic tasks	Long context, multimodal

Benchmark Comparison

Benchmark	Grok 4.5	Gemini 3.1 Pro	Winner
DeepSWE 1.0	62.0%	~54%	Grok 4.5
Terminal-Bench 2.1	83.3%	~79%	Grok 4.5
SWE Marathon (pass@1)	29.0%	~24%	Grok 4.5
SWE-bench Pro	~63%	~62%	Grok 4.5
ARC-AGI-2	~62%	~77%	Gemini 3.1 Pro
MRCR-v2 (1M context)	N/A (500K max)	~90%	Gemini 3.1 Pro
GPQA Diamond	~87%	~94%	Gemini 3.1 Pro
MMLU Pro	~86%	~88%	Gemini 3.1 Pro
HLE	~48%	~52%	Gemini 3.1 Pro

The pattern: Grok 4.5 dominates coding-specific benchmarks. Gemini 3.1 Pro dominates reasoning, science, and long-context recall.

Where Each Wins

Grok 4.5 wins for:

Coding pipelines — leads DeepSWE, Terminal-Bench, SWE Marathon
Cursor integration — co-trained with real developer data
Lower per-task cost — $6 output vs Gemini’s $12
X / Grok ecosystem — native chat, X Premium+ access
Predictable pricing — no preview/GA tier shifts

Gemini 3.1 Pro wins for:

Long context (>500K) — 1M default, up to 2M for select customers
Multimodal reasoning — native audio and video understanding
ARC-AGI-2 — the abstract reasoning benchmark leader (~77%)
Science / research — GPQA Diamond, MMLU Pro top scores
Google Workspace — native Docs, Sheets, Gmail, YouTube integration
Deep Think mode — extended reasoning for hard problems

Cost Modeling

For 10,000 typical coding tasks (30K input / 5K output):

Model	Monthly Cost
Grok 4.5	$900
Gemini 3.1 Pro	$1,200
Claude Sonnet 5 (intro)	$1,100
GPT-5.6 Sol	$3,000

For 1,000 RAG tasks (200K input / 2K output — long-context work):

Model	Monthly Cost
Grok 4.5	$412
Gemini 3.1 Pro	$424
GPT-5.6 Sol	$1,150

On very-long-context workloads (>500K), Grok 4.5 can’t compete — Gemini 3.1 Pro takes the field by default.

Decision Framework

What's your workload?
│
├── Coding + IDE / Cursor-native
│   → Grok 4.5
│
├── Long documents / whole-repo context
│   → Gemini 3.1 Pro (1M-2M window)
│
├── Multimodal (video, audio, images together)
│   → Gemini 3.1 Pro (only native option)
│
├── ARC-AGI-2 / abstract reasoning
│   → Gemini 3.1 Pro (~77%)
│
├── Google Workspace integration
│   → Gemini 3.1 Pro
│
├── Cheapest capable frontier model overall
│   → Grok 4.5
│
└── Real developer coding trajectories in training
    → Grok 4.5 (Cursor co-trained)

Ecosystem Comparison

Feature	Grok 4.5	Gemini 3.1 Pro
First-party CLI	❌	⚠️ Gemini CLI (beta)
AI Studio / Playground	grok.com	AI Studio
Vertex AI	❌	✅
Bedrock	❌	❌
Azure AI Foundry	❌	❌
MCP support	✅	✅
Cursor native	✅ (co-trained)	✅

The Bottom Line

If your workload is coding-heavy and fits in 500K tokens, Grok 4.5 is the pick — cheaper output, better coding benchmarks, native Cursor integration.

If your workload is multimodal, long-context (>500K), or research-oriented, Gemini 3.1 Pro is the pick — the 1M window, native video/audio, and Google Workspace hooks matter more than the $6 vs $12 output-token gap.

For a balanced production stack, run both: Grok 4.5 for code, Gemini 3.1 Pro for long-context RAG and multimodal work.

Sources

Grok 4.5 Launch (SpaceXAI) — official launch details
Gemini 3.1 Pro on AI Studio — model docs
Gemini API Pricing — official pricing
Artificial Analysis Intelligence Index — benchmarks