Key Facts
  • Google has released 3 major Gemini generations since early 2025 — Gemini 2.0, 2.5 Pro, and now Gemini 3.1 Pro
  • Gemini 3.1 Pro (February 2026) leads reasoning benchmarks: 94.3% GPQA Diamond, 77.1% ARC-AGI-2
  • Gemini 2.5 Pro is entering deprecation — scheduled shutdown June 17, 2026
  • Gemini 2.0 Flash remains available but is no longer Google's flagship
  • Gemini 3.1 Pro matches predecessor pricing at $2/$12 per million tokens — a major upgrade at no extra cost

In February 2025, Google made Gemini 2.0 available to everyone. Fourteen months later, that launch is three model generations behind. Google has shipped Gemini 2.5 Pro, Gemini 3 Pro, Gemini 3 Deep Think, and Gemini 3.1 Pro — faster model iteration than anyone expected.

Here's a complete guide to where Google's AI lineup stands in March 2026, what changed with each generation, and which model you should actually use.

The Full Gemini Timeline

Each generation has been a meaningful leap. Gemini 2.0 was Google's public catch-up moment after ChatGPT's dominance. Gemini 2.5 Pro introduced genuine reasoning. Gemini 3.1 Pro is where Google reclaimed benchmark leadership.

What Gemini 2.0 Was (And Why It Mattered)

When Gemini 2.0 launched in February 2025, it was the first time Google made a truly competitive model available to everyone without waitlists or enterprise gates. Three variants shipped together:

Gemini 2.0 Flash — the main model. Faster than Gemini 1.5 Flash, 1 million token context window, native multimodal input (text, images, audio, video), and built-in tool use. At $0.10 per million input tokens, it was aggressively priced.

Gemini 2.0 Flash-Lite — cost-optimized variant for high-volume, lower-complexity tasks.

Gemini 2.0 Pro Experimental — more capable, experimental, for developers who needed maximum performance.

Gemini 2.0 Flash proved that a "non-flagship" model could handle most real-world tasks well. It remains available today, but it's no longer the model you should build on if performance matters.

Gemini 2.5 Pro: The Thinking Model

Gemini 2.5 Pro was Google's first "thinking model" — it reasoned through problems step by step before generating a response, similar to OpenAI's o-series models.

At launch, it topped the LMArena leaderboard by a 40+ point margin. Its benchmark numbers at release:

Benchmark Score
GPQA Diamond (scientific reasoning) 84.0%
AIME 2025 (math) 86.7%
SWE-Bench Verified (coding) 63.8%
LiveCodeBench v5 70.4%
MRCR at 128k context 94.5%

The 2 million token context window (for trusted testers) was also a headline feature. For processing entire codebases or lengthy research corpora, it was unmatched.

Gemini 2.5 Pro is now in deprecation. If you're using it in production, migrate before June 17, 2026.

Gemini 3.1 Pro: The Current Flagship

Gemini 3.1 Pro, released February 2026, is the model to use right now. It represents a step-change in reasoning capability:

**GPQA Diamond**: 94.3% — highest of any model in the world (beats GPT-5.4's 92.8%)
**ARC-AGI-2**: 77.1% — more than double Gemini 3 Pro's score
**ARC-AGI-2 vs. Claude Opus 4.6**: 77.1% vs. 68.8% — Gemini leads
**ARC-AGI-2 vs. GPT-5.4**: 77.1% vs. 73.3% — Gemini leads
**Pricing**: $2 input / $12 output per million tokens — same as predecessor

ARC-AGI-2 tests the ability to recognize novel patterns — tasks that can't be memorized from training data. Gemini 3.1 Pro's 77.1% is considered a landmark result for the field.

Where Gemini 3.1 Pro Doesn't Lead

Coding is not Gemini's strongest suit. On SWE-Bench Verified, Claude Opus 4.6 scores 80.8% compared to Gemini 3.1 Pro's considerably lower result. For software development work, Claude remains the stronger choice.

Human preference rankings also favor Anthropic models. Claude Sonnet 4.6 leads the GDPval-AA Elo leaderboard at 1,633 points. Gemini 3.1 Pro is a benchmark winner, not necessarily a writing quality winner.

Which Gemini Model Should You Use?

Pros
    Cons
      ℹ️
      Migration warning: Gemini 2.5 Pro will be fully deprecated on June 17, 2026. If you have production applications running on 2.5 Pro, migrate to Gemini 3.1 Pro now. The API interface is compatible and performance is substantially better.

      Gemini 3.1 Pro vs. Competitors at a Glance

      Model GPQA Diamond ARC-AGI-2 SWE-Bench Price (input/output per M)
      Gemini 3.1 Pro 94.3% 77.1% — $2 / $12
      GPT-5.4 92.8% 73.3% — $2.50 / $15
      Claude Opus 4.6 89.1% 68.8% 80.8% $5 / $25
      Claude Sonnet 4.6 — — — $3 / $15

      For reasoning, research, and multimodal tasks, Gemini 3.1 Pro is the price-performance leader in March 2026. You're getting the world's top reasoning scores at one of the lowest price points among flagship models.

      How to Access Gemini 3.1 Pro

      • Gemini app (gemini.google.com) — available on Google One AI Premium plan
      • Google AI Studio — free tier access for experimentation
      • Vertex AI — enterprise API with SLAs, private deployment options
      • Gemini API — direct access at $2/$12 per million tokens

      For most developers, Google AI Studio is the fastest way to test Gemini 3.1 Pro capabilities before committing to API integration.

      The Bottom Line

      Google's Gemini has gone from a competitive-but-second-place model in early 2025 to the clear benchmark leader in reasoning by March 2026. Gemini 2.0 was the democratization moment. Gemini 2.5 Pro introduced reasoning. Gemini 3.1 Pro made Google number one on the tests that matter most.

      If you're building something where scientific reasoning, large-context analysis, or cost-efficient frontier capability matters, Gemini 3.1 Pro is the model to use right now.