Gemma 4 vs Grok 4.3: Open Weights vs Cheap Closed for Cost-Efficient AI in May 2026

Google released Gemma 4 on April 2, 2026, under an Apache 2.0 license. xAI released Grok 4.3 on April 30. Both models occupy the cost conscious end of the AI infrastructure spectrum. Gemma 4 31B is available at $0.13 per million input tokens and $0.38 per million output tokens through OpenRouter, making it the cheapest capable model in this comparison by a wide margin. Grok 4.3 ships at $1.25 input and $2.50 output, roughly 10x more expensive on input and 6.5x more expensive on output than Gemma 4 31B at API list rates.

The Grok 4.3 premium buys something real. The Artificial Analysis Intelligence Index of 53 is a higher composite score than Gemma 4 31B carries in publicly disclosed individual benchmarks. Grok leads on legal and financial domain work, holds the lowest published hallucination rate among production closed models, and posts a 1500 ELO on GDPval-AA. Gemma 4 leads on reasoning benchmarks where scores are disclosed, carries full open weights under a permissive license, and extends to audio and edge deployment through the E-series variants.

This is not a comparison between a good model and a bad one. It is a deployment philosophy decision.

The Models at a Glance

What Each Model Is Built For

Gemma 4

Gemma 4 is built around intelligence per parameter and deployment flexibility. The 31B dense model competes with much larger closed models on reasoning benchmarks. The 26B A4B MoE optimizes for inference cost at nearly the same capability profile. E2B and E4B variants target phones, browsers, and embedded devices, with native audio input across the smaller end of the family.

The Apache 2.0 license is commercially permissive with no use restrictions that earlier Gemma releases imposed. Full open weights means Gemma 4 is self hostable on any inference stack, fine tunable on proprietary data, and deployable in air gapped environments. A single H100 handles the 31B dense model at production latency. The 26B A4B MoE runs on smaller hardware given the 4B active parameter footprint.

On published benchmarks, Gemma 4 31B posts GPQA Diamond at 84.3%, MMLU Pro at 85.2%, LiveCodeBench v6 at 80.0%, AIME 2025 at 89%, and Codeforces ELO at 2150. These are competitive numbers across reasoning, math, and coding contests.

Grok 4.3

Grok 4.3 is a closed frontier model optimized for cost efficiency within the proprietary tier. The April 30 release cut input pricing roughly 40% and output pricing roughly 60% from Grok 4.20. The result is the cheapest closed frontier model available from any major lab.

Native video input arrived with 4.3 as an xAI first among production closed models. The model posts a 1500 ELO on GDPval-AA, leads CaseLaw v2 at 79.3%, and holds the top position on CorpFin. The Artificial Analysis Intelligence Index of 53 is a composite signal that places Grok 4.3 meaningfully above the open weights tier in that index's methodology.

The closed weights posture means Grok 4.3 is not self hostable, not fine tunable, and not deployable outside the xAI API or OpenRouter. For teams with data residency requirements, air gapped deployment needs, or proprietary fine tuning goals, Grok 4.3 is not a candidate regardless of price.

Benchmark Comparison

The two models publish on largely non overlapping benchmark suites. Gemma 4 leads on disclosed reasoning, math, and coding contest benchmarks. Grok 4.3 leads on published professional domain benchmarks in legal and finance. Neither team has published against the other's benchmark suite in a comparable head to head evaluation.

For teams choosing between them, the practical question is which benchmark category aligns with their production workload. Reasoning and math heavy tasks favor Gemma on the disclosed numbers. Legal research, financial analysis, and general professional knowledge work favor Grok on the disclosed numbers.

Multimodal Capability

Gemma 4 covers text, image, video, and audio natively across the family. Variable aspect ratio and resolution handling are built in. The E2B and E4B variants include native audio input for on device voice applications. This is the broadest open weights multimodal coverage that has ever shipped.

Grok 4.3 introduced native video input with this release. Text and image input are also supported. Audio is not part of the Grok 4.3 surface.

For workflows that need audio input natively in an open weights deployment, Gemma 4 is the only viable option. For video input on a closed API at the lowest available price, Grok 4.3 is competitive with Gemma's managed inference options (which are currently available through OpenRouter rather than Google's own Vertex AI for Gemma 4).

Deployment Flexibility

This is the dimension that most clearly separates the two models.

Gemma 4 runs on Hugging Face, Kaggle, Ollama, Google AI Studio, and any self hosted inference stack. The open weights and permissive license mean fine tuning on proprietary data is available without any vendor relationship. For teams with air gapped deployments, data residency requirements in regulated industries, or fine tuning pipelines on private codebases, Gemma 4 is accessible where Grok 4.3 is not.

Grok 4.3 is available only through the xAI API and OpenRouter. There is no self hosted path, no fine tuning surface, and no deployment option outside those endpoints. For teams that need control over their inference stack, Grok 4.3 is not a candidate.

The edge deployment story also favors Gemma. The E2B and E4B variants run on mobile devices and in the browser with native audio input. Grok 4.3 has no equivalent.

Pricing and Total Cost

At API list rates, Gemma 4 26B A4B MoE is roughly 16x cheaper on input and 7x cheaper on output than Grok 4.3. At 100 million output tokens per month: $35 on Gemma 4 MoE versus $250 on Grok 4.3. At 1 billion output tokens monthly: $350 versus $2,500.

For teams that self host Gemma 4, the marginal cost per token is the amortized compute cost, which flattens to a fixed infrastructure line regardless of volume. High volume generation workloads on Gemma 4 self hosted inference converge toward dramatically lower cost per token than any API based model at scale.

The Grok 4.3 premium, roughly 7x on output at list rates, buys the Intelligence Index of 53, the legal and financial domain benchmark leadership, and the lowest hallucination rate among production closed models. Whether that premium is justified depends on whether your workload matches those specific capability advantages.

Direct Comparison Table

Which One Should You Use

Use Gemma 4 when:

• Open weights under a permissive license are required for your deployment posture
• Self hosting or air gapped inference is a requirement
• Fine tuning on proprietary data is part of the roadmap
• Multimodal input includes audio as a first class signal
• Edge or on device deployment is required (E2B / E4B variants)
• Cost per token at API rates is the dominant variable and the Gemma capability profile matches your workload
• Reasoning, math, and coding contest benchmarks are the most relevant quality signals

Use Grok 4.3 when:

• You need a closed API with no infrastructure overhead
• Legal research, financial analysis, or general professional knowledge work is the core workload
• The lowest hallucination rate among production closed models is a priority
• A 1M token context window is required (versus Gemma's 256K open weights limit)
• You want the highest Intelligence Index among sub $2.00 output per million models
• Native video input at the lowest closed API price point is the goal

Use both when:

• Gemma 4 handles multimodal generation, reasoning tasks, audio workflows, and cost sensitive batch generation
• Grok 4.3 handles legal and financial domain work, long context processing, and pipelines requiring the lowest hallucination rate
• Gemma 4 self hosted inference covers volume; Grok 4.3 API covers the specialty domains
• Route by deployment requirement and workload shape rather than provider

Our Default for May 2026

For teams with open weights requirements, fine tuning needs, or edge deployment goals, Gemma 4 is the most capable and most permissively licensed open family that has ever shipped. The benchmarks on reasoning, math, and coding contests are competitive with models several times its parameter count. At $0.13 / $0.38 per million tokens through OpenRouter, the API price is also the lowest capable option available.

For teams running closed API workloads in legal and financial domains, needing a 1M context window, or prioritizing the lowest hallucination rate among closed models, Grok 4.3 is the strongest option in its price tier. The 10x input cost premium over Gemma 4 31B is meaningful, but so are the domain benchmark advantages and the closed API simplicity.

A production AI architecture in May 2026 does not choose between open and closed as a philosophy. It routes by workload requirements and cost thresholds, using Gemma 4 where open weights, audio, or edge deployment matter, and using Grok 4.3 where closed API simplicity, context length, and domain specialization justify the premium.

How Contra Collective Bridges the Gap

Contra Collective runs Gemma 4, Grok 4.3, Qwen 3.6, Opus 4.7, GPT-5.5, and Gemini 3.1 Pro in production across coding pipelines, multimodal content systems, and multi agent workflows for enterprise clients. We architect systems that use the right model at each stage rather than defaulting to a single provider. Ready to make the right call for your stack? Book a free technical audit, no sales pitch, just clarity.