Gemini 3.5 Flash vs Grok 4.3
Gemini 3.5 Flash (2026) and Grok 4.3 (2026) are frontier-tier reasoning models from Google DeepMind and xAI. Gemini 3.5 Flash ships a 1.05m-token context window, while Grok 4.3 ships a 1m-token context window. On Google-Proof Q&A, Gemini 3.5 Flash leads by 2.1 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Gemini 3.5 Flash is safer overall; choose Grok 4.3 when vision-heavy evaluation matters.
Decision scorecard
Local evidence first| Signal | Gemini 3.5 Flash | Grok 4.3 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | RAG, Agents, and Long context |
| Context window | 1.05m | 1m |
| Cheapest output | $9/1M tokens | $2.50/1M tokens |
| Provider routes | 4 tracked | 5 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 1 shared |
Decision tradeoffs
- Gemini 3.5 Flash holds a shared-benchmark lead on Google-Proof Q&A, ahead by 2.1 points.
- Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.5 Flash uniquely exposes Code execution in local model data.
- Local decision data tags Gemini 3.5 Flash for Coding, RAG, and Agents.
- Grok 4.3 has the lower cheapest tracked output price at $2.50/1M tokens.
- Grok 4.3 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Grok 4.3 for RAG, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3.5 Flash
$3,450
Cheapest tracked route/tier: Google AI Studio
Grok 4.3
$1,625
Cheapest tracked route/tier: xAI Console
Estimated monthly gap: $1,825. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Grok 4.3 is $6.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution before moving production traffic.
- Provider overlap exists on Vercel AI Gateway and OpenRouter; start route-level A/B tests there.
- Gemini 3.5 Flash is $6.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Gemini 3.5 Flash adds Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-19 | 2026-05-06 |
| Context window | 1.05m | 1m |
| Parameters | — | ~0.5T |
| Architecture | Decoder Only | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-01 | 2024-11 |
Pricing and availability
| Pricing attribute | Gemini 3.5 Flash | Grok 4.3 |
|---|---|---|
| Input price | $1.50/1M tokens |
|
| Output price | $9/1M tokens |
|
| Providers |
Capabilities
| Capability | Gemini 3.5 Flash | Grok 4.3 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Gemini 3.5 Flash | Grok 4.3 |
|---|---|---|
| Google-Proof Q&A | 92.2 | 90.1 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Gemini 3.5 Flash at 92.2 and Grok 4.3 at 90.1, with Gemini 3.5 Flash ahead by 2.1 points. The largest visible gap is 2.1 points on Google-Proof Q&A, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on code execution: Gemini 3.5 Flash. Both models share vision, multimodal input, reasoning mode, and function calling, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Gemini 3.5 Flash lists $1.50/1M input and $9/1M output tokens on the cheapest tracked provider, while Grok 4.3 lists tiered pricing: 0-200,001t is $1.25/1M input and $2.50/1M output; 200,001t+ is $2.50/1M input and $5/1M output. A 70/30 input-output blend puts Grok 4.3 lower by about $2.12 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 4 providers versus 5, so concentration risk also matters.
Choose Gemini 3.5 Flash when coding workflow support and larger context windows are central to the workload. Choose Grok 4.3 when vision-heavy evaluation, lower cheapest-tier input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 3.5 Flash or Grok 4.3?
Gemini 3.5 Flash supports 1.05m tokens, while Grok 4.3 supports 1m tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 3.5 Flash or Grok 4.3?
Gemini 3.5 Flash lists $1.50/1M input and $9/1M output tokens on the cheapest tracked provider. Grok 4.3 lists tiered pricing: 0-200,001t is $1.25/1M input and $2.50/1M output; 200,001t+ is $2.50/1M input and $5/1M output. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Gemini 3.5 Flash or Grok 4.3 open source?
Gemini 3.5 Flash is listed under Proprietary. Grok 4.3 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 3.5 Flash or Grok 4.3?
Both Gemini 3.5 Flash and Grok 4.3 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Gemini 3.5 Flash or Grok 4.3?
Both Gemini 3.5 Flash and Grok 4.3 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 3.5 Flash and Grok 4.3?
Gemini 3.5 Flash is available on Google AI Studio, GCP Vertex AI, Vercel AI Gateway, and OpenRouter. Grok 4.3 is available on xAI Console, OpenRouter, Microsoft Foundry, Vercel AI Gateway, and AWS Bedrock. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-18. Data sourced from public model cards and provider documentation.