Gemma 4 31B vs GPT-4o-mini

Overview (our 12-test suite): Gemma wins 9 tests; GPT-4o-mini wins 1; 2 ties. Detailed walk-through (Gemma score vs GPT-4o-mini score):

• structured output: Gemma 5 vs GPT-4o-mini 4 — Gemma is tied for 1st (tied with 24 others) on JSON/schema adherence, meaning better reliability for schema-constrained APIs and data extraction.
• strategic analysis: Gemma 5 vs GPT-4o-mini 2 — Gemma is tied for 1st (with 25 others) on nuanced tradeoff reasoning; useful for pricing, forecasting, or multi-criteria decisions.
• tool calling: Gemma 5 vs GPT-4o-mini 4 — Gemma tied for 1st (with 16 others) on function selection and argument accuracy, so it's stronger for agentic/tool-driven workflows.
• faithfulness: Gemma 5 vs GPT-4o-mini 3 — Gemma tied for 1st (with 32 others) indicating fewer hallucinations when sticking to source material.
• persona consistency: Gemma 5 vs GPT-4o-mini 4 — Gemma tied for 1st (with 36 others), better at maintaining voice and resisting prompt injection.
• agentic planning: Gemma 5 vs GPT-4o-mini 3 — Gemma tied for 1st (with 14 others), better at goal decomposition and recovery.
• multilingual: Gemma 5 vs GPT-4o-mini 4 — Gemma tied for 1st (with 34 others), stronger non-English parity.
• creative problem solving: Gemma 4 vs GPT-4o-mini 2 — Gemma ranks 9 of 54 (21 models share), better for non-obvious, feasible ideas.
• constrained rewriting: Gemma 4 vs GPT-4o-mini 3 — Gemma ranks 6 of 53, better at tight character/format compression.
• classification: tie 4 vs 4 — both tied for 1st (with 29 others), so routing/categorization quality is equivalent in our tests.
• long context: tie 4 vs 4 — both rank 38 of 55 (17 models share), so retrieval at 30K+ tokens is similar.
• safety calibration: Gemma 2 vs GPT-4o-mini 4 — GPT-4o-mini ranks 6 of 55 (tied with 3) showing stronger refusal/allow behavior compared with Gemma (rank 12 of 55). This is GPT-4o-mini's clear advantage. Additional external math signals: GPT-4o-mini scores 52.6% on MATH Level 5 and 6.9% on AIME 2025 according to Epoch AI; those place it near the lower end for those specialized math benchmarks (rank 13/14 on MATH Level 5 and 21/23 on AIME 2025). The payload includes no external math percentages for Gemma. Implication for tasks: Gemma's high marks and top-tier rankings in structured output, tool calling, faithfulness, and agentic planning make it the safer choice for production APIs that need reliable data formats, tool integrations, and multilingual support. GPT-4o-mini is the better pick when safety refusal behavior is a decisive requirement.

Raw per-mTok pricing from the payload: Gemma 4 31B input $0.13 / output $0.38; GPT-4o-mini input $0.15 / output $0.60. Assuming a 50/50 split of input/output tokens: 1M tokens (1,000 mTok) costs Gemma $255 and GPT-4o-mini $375 — a $120 monthly gap. At 10M tokens: Gemma $2,550 vs GPT-4o-mini $3,750 (difference $1,200). At 100M tokens: Gemma $25,500 vs GPT-4o-mini $37,500 (difference $12,000). High-volume apps (SaaS APIs, conversational platforms, large-scale inference) should care about this gap; at those volumes the cheaper per-token cost of Gemma materially reduces operating expense. Low-volume or highly safety-sensitive deployments might accept GPT-4o-mini's higher cost for its stronger safety calibration score.

Choose Gemma 4 31B if you need: reliable JSON/schema outputs, high faithfulness, strong tool-calling/agentic planning, multilingual parity, or lower per-token cost — e.g., data-extraction APIs, multi-language customer support, tool-driven agents, or high-volume inference. Choose GPT-4o-mini if you need stronger safety calibration (it scores 4 vs Gemma's 2) and are willing to pay more per token for that behavior — e.g., moderation-sensitive assistants or deployments where refusal/permit behavior is paramount.