Gemma 4 vs Grok 4: Open-Source vs Frontier AI
Google's free Gemma 4 against xAI's speed-optimized Grok 4 — detailed benchmarks, cost analysis, and practical use case recommendations for developers.
Gemma 4 vs Grok 4: Overview
Google's Gemma 4 31B and xAI's Grok 4 represent opposite ends of the AI model spectrum. Gemma 4 is a free, open-source model you can run on your own hardware. Grok 4 is a closed, frontier-class model optimized for speed and integrated into the X (formerly Twitter) ecosystem. This comparison explores when each model makes sense.
Benchmark Comparison
| Benchmark | Gemma 4 31B | Grok 4.20 |
|---|---|---|
| GPQA Diamond | 84.3% | 88% |
| AIME 2026 | 89.2% | — |
| MMLU Pro | 85.2% | — |
| LiveCodeBench v6 | 80% | — |
| HumanEval | — | 98% |
| Arena ELO | 1452 | 1490 |
| AA Index | — | 49 |
Grok 4.20 leads on GPQA Diamond (88% vs 84.3%) and Arena ELO (1490 vs 1452), but the gaps are smaller than one might expect given the difference in model class. Gemma 4 31B holds its own with strong AIME 2026 (89.2%) and LiveCodeBench v6 (80%) scores where Grok data is not yet available.
Grok 4.20 is a frontier-class closed model with far more compute behind it. The question isn't whether Grok 4.20 is stronger overall (it likely is), but whether the quality gap justifies the cost difference.
Cost Analysis
| Factor | Gemma 4 31B | Grok 4.20 |
|---|---|---|
| Model Cost | Free (Apache 2.0, free on AI Studio) | API pricing / X Premium+ |
| API Input | $0.14 / 1M tokens (free on AI Studio) | $2 / 1M tokens |
| API Output | $0.40 / 1M tokens (free on AI Studio) | $6 / 1M tokens |
| Context Window | 256K | 2M |
| Speed | 102 tok/s | 232 tok/s |
| Hardware Needed | RTX 4090 or equivalent | None (cloud) |
| Data Privacy | Complete (local) | Data sent to xAI |
Gemma 4 is free on Google AI Studio and extremely cheap via API ($0.14/$0.40 per MTok). Even self-hosted, the total cost of ownership can approach $0 per token after the hardware investment.
Grok 4.20's API pricing ($2/$6 per MTok) is moderate for a frontier model but still 14-15x more expensive than Gemma 4's API pricing. For high-volume applications, the cost difference is enormous.
Break-Even Calculation
Assuming a $2,000 GPU investment and Grok 4.20 API costs of ~$3 per million tokens (blended):
- At 1M tokens/day: Gemma 4 pays for itself in ~22 months (or use AI Studio for free)
- At 10M tokens/day: Gemma 4 pays for itself in ~67 days
- At 100M tokens/day: Gemma 4 pays for itself in ~7 days
For low-volume personal use, Grok 4.20's API might be simpler. For anything at scale, Gemma 4 (via AI Studio or self-hosted) is dramatically more economical.
Speed Comparison
Grok 4.20 is optimized for speed at 232 tokens/second — one of the fastest frontier models available. xAI has invested heavily in inference infrastructure for real-time applications.
Gemma 4 31B runs at 102 tokens/second via Google's infrastructure, which is quite fast for its class. Local speed depends on your hardware:
- RTX 4090: ~30-40 tokens/second (Q4 quantized)
- M2 Ultra: ~25-35 tokens/second
- RTX 3090: ~15-25 tokens/second
For real-time applications, Grok 4.20's cloud infrastructure delivers more than double the speed of Gemma 4.
Unique Strengths
Gemma 4 31B
- Completely free — Apache 2.0 license
- Full data privacy — nothing leaves your machine
- Offline capable — works without internet
- Fine-tunable — adapt to your specific domain
- No rate limits — process as much as your hardware allows
Grok 4.20
- Frontier intelligence — stronger reasoning (GPQA Diamond 88%, Arena ELO 1490)
- Real-time knowledge — integrated with X for current events
- Speed — 232 tok/s, optimized cloud inference
- 2M token context window — much larger than Gemma's 256K
- No hardware investment — start immediately
- Humor and personality — Grok's distinctive conversational style
Use Case Recommendations
Choose Gemma 4 31B if:
- Budget is a constraint — free model, free inference
- Privacy is critical — medical, legal, or sensitive data
- High volume — millions of tokens per day
- Offline deployment — edge devices, air-gapped systems
- Customization needed — fine-tuning for specific domains
Choose Grok 4.20 if:
- You need the best quality available — frontier-class performance
- Real-time information matters — current events, trending topics
- Speed is critical — 232 tok/s is among the fastest available
- Large context — 2M token window for massive documents
- Low volume — occasional use doesn't justify hardware investment
Verdict
Gemma 4 and Grok 4.20 don't really compete head-to-head — they serve different needs. Gemma 4 is the best free, private, local AI option available, with surprisingly strong benchmarks (GPQA Diamond 84.3%, AIME 2026 89.2%). Grok 4.20 is a fast (232 tok/s), capable frontier model with a massive 2M context window for users who need top-tier speed and are willing to pay for it.
If you can afford Grok 4.20 and need speed and large context, use it. If you want capable AI at minimal cost with full privacy, Gemma 4 31B is hard to beat.