Gemini 3.1 vs 2.5: Know the Differences

In reasoning, Google Gemini 3.1 Pro Preview (Feb 2026) is better than 2.5 Pro (June 2025 flagship), tops LMSYS Arena 1501 Elo vs 1420, and better at math/coding through improved chain-of-thought, 3.1 has 2M token context (vs 1M) and improved video analysis, multimodality (text/image/audio/video) structured output from agents; cheaper inference suits are used by developers, 2. The trend 3.1: beat Sonnet 4.6 cost-effectively, advanced agents.

Benchmark Gains

LMSYS Arena: 3.1 1501 Elo crushes 2.5’s 1420; real-user prefs favor nuanced responses.

Math/Coding: 3.1 stronger multi-step chains; 2.5 SWE-Bench leader stable production.

Preview tests show 3.1 10-15% uplift for complex queries.

Context & Multimodality

Tokens: 3.1 2M vs 2.5 1M; deeper docs/codebases.

Vision/Video: Both strong; 3.1 temporal reasoning sharper in real-time.

Audio TTS native both, 3.1 faster responsive agents.

Availability & Use Cases

2.5 Pro: Full public/enterprise stable apps.

3.1 Preview: Vertex AI/Gemini CLI select users; experimental reasoning power.

Devs pick 2.5 reliability, bleeding-edge 3.1.

Official Social Update

FAQs

Gemini 3.1 available now?
Preview Vertex AI/Gemini CLI select users; full GA soon. 2.5 Pro public Gemini Advanced stable choice.

Coding which better?
3.1 preview edges multi-step; 2.5 Pro mature SWE-Bench 63.8% web apps/agents production-ready.

Context window sizes?
3.1 2M tokens long docs/code; 2.5 1M (2M soon) sufficient for most tasks cost lower.

Multimodal improvements?
3.1 superior video reasoning/agents; 2.5 balanced text/image/audio reliable consumer.

Cost inference compare?
3.1 cheaper than Sonnet 4.6 benchmarks; 2.5 optimized scale enterprise savings volumes.