Gemini 2.0 Pro's 2 Million Token Context: What Can You Actually Do With It?

Gemini 2.0 Pro Experimental’s 2 million token context window lets you feed it an entire large codebase, a year’s worth of legal filings, or 19 hours of audio in a single request. In practice, it delivers on that promise for retrieval-heavy tasks—but accuracy degrades meaningfully as context fills, and the cost of processing that much text at scale adds up fast.

What 2 Million Tokens Actually Means

Raw numbers don’t communicate scale. Two million tokens maps to roughly 1.5 million words, or about 15 full-length novels stacked end to end. In practitioner terms, that means:

• A complete codebase with 40,000+ lines of source across hundreds of files
• Twelve dense legal contracts totaling 847 pages, simultaneously cross-referenced
• An entire academic literature review, including cited papers and methodology sections
• Up to 19 hours of audio processed without segmentation¹

Google released Gemini 2.0 Pro Experimental on February 5, 2025, as part of the Gemini 2.0 family expansion—and the 2 million token limit matched the ceiling set by its predecessor, Gemini 1.5 Pro.² What changed was the underlying model: stronger coding performance, better world-knowledge reasoning, and native tool use (code execution, Google Search). The context window didn’t grow—the model filling it got more capable.

What You Can Actually Do With It

Codebase Analysis at Scale

The most well-validated use case is software development. By loading an entire repository into context, Gemini 2.0 Pro can trace dependencies across files without needing chunked retrieval, which eliminates the fragmentation problem that plagues RAG-based code assistants. Google’s developer documentation demonstrates this workflow with repositories that exceed standard tool limits.⁴

Practitioners report using this for:

• Legacy migration: Feeding a 35,000-line application and requesting a full migration plan, with cross-file dependency analysis intact
• Bug archaeology: Asking why a specific behavior exists by pointing at a symptom without knowing which file contains the cause
• Refactoring scope assessment: Understanding the blast radius of an architectural change before writing a line

# Example: Load a full repository for context-aware analysis
import google.generativeai as genai
import os

def load_repo_context(repo_path: str) -> str:
    """Concatenate repository source files into a single context string."""
    context_parts = []
    for root, _, files in os.walk(repo_path):
        for file in files:
            if file.endswith(('.py', '.ts', '.go', '.rs')):
                filepath = os.path.join(root, file)
                with open(filepath, 'r', errors='ignore') as f:
                    context_parts.append(f"# FILE: {filepath}\n{f.read()}")
    return "\n\n".join(context_parts)

model = genai.GenerativeModel("gemini-2.0-pro-exp")
repo_context = load_repo_context("./src")
response = model.generate_content([repo_context, "Identify all circular dependencies and suggest a resolution order."])

Legal and Compliance Work

Legal teams processing large document sets have reported measurable gains. One documented example involves simultaneously processing 12 related contracts to identify contradictory clauses and compliance issues—work that previously required sequential review sessions.⁵ A financial services firm using a similar approach reported 60% faster contract review cycles after implementation.⁵

The key here is cross-document reasoning—something that single-document analysis or traditional search misses. When clause A in one contract conflicts with clause B in another, only a model that holds both in active context can catch it reliably.

Research and Document Synthesis

Researchers feeding entire literature review bodies into context can ask comparative questions that span methodology, results, and citation networks across dozens of papers simultaneously. This is distinct from summarization—the model can answer “which three studies have contradictory findings on X and what methodology explains the discrepancy?” without the researcher knowing in advance which papers contain the answer.

The Hard Limits: Context Rot and the Middle Problem

Here’s what Google’s marketing doesn’t lead with: filling a context window and using it reliably are different things.

The “Lost in the Middle” phenomenon, formally documented in a 2023 MIT Press study, shows a characteristic U-shaped performance curve across all long-context models.⁶ Models perform best when relevant information sits at the beginning (primacy bias) or end (recency bias) of the input, with performance degrading for information buried in the middle. This isn’t a Gemini-specific flaw—it’s a structural property of transformer attention at scale.

Chroma’s 2025 “Context Rot” research pushed further: across 18 tested frontier models, every single one showed degrading accuracy as input length increased.⁷ The mechanism involves three compounding effects:

1. Attention dilution: Each additional token competes for a fixed “attention budget”
2. Distractor interference: Irrelevant content obscures signal as the haystack grows
3. Lost-in-the-middle effect: Positional biases override semantic relevance for mid-context content

Independent analysis suggests effective reliable capacity typically runs at 60–70% of advertised token limits—meaning a model claiming 2 million tokens often shows meaningful performance degradation around 1.2–1.4 million tokens under realistic workloads.⁸

Gemini 1.5 Pro achieved >99.7% recall on single needle-in-haystack tasks at 1 million tokens in formal testing.⁹ Specific published benchmarks for Gemini 2.0 Pro at the full 2 million token limit are more limited in the public record—a gap worth noting before relying on those extremes in production.

Model Comparison: Long Context Landscape

At time of writing (February 2026), the long-context model landscape has shifted considerably from when Gemini 2.0 Pro launched:

¹⁰¹¹¹²

The comparison reveals a counterintuitive pattern: Google’s 2025 successor models to Gemini 2.0 Pro actually shipped with smaller context windows, suggesting the 2 million token limit carries real infrastructure and quality costs that Google opted to constrain in newer releases.

What It Costs

Gemini 2.0 Pro launched as an experimental model available free through Google AI Studio and via Vertex AI, and to Gemini Advanced subscribers via the model selector.² The experimental designation means pricing and availability remain subject to change.

For reference, Gemini 2.5 Pro—the subsequent release—introduced formal pricing at $1.25 per million input tokens and $10.00 per million output tokens for standard context, with long-context pricing applying above 200K tokens.¹³

At those rates, processing a single 2-million-token prompt costs approximately $2.50 in input alone. For iterative workflows where the same large context is queried multiple times, Google’s context caching API reduces costs significantly—cached context runs at $4.50 per million tokens per hour rather than re-processing charges.¹³ A codebase loaded once and queried fifty times becomes economically viable; loading it fresh fifty times does not.

When the 2 Million Token Window Changes the Outcome

The context window matters most when the task requires cross-document reasoning that can’t be chunked. Specific patterns where it makes a categorical difference:

• Contradiction detection across a document corpus (legal, compliance, policy)
• Dependency tracing in large codebases where chunking breaks reference chains
• Synthesis across timeline in long research threads or customer correspondence histories
• Multi-modal sessions combining extended text, audio transcripts, and code

It matters less—and alternative approaches often outperform—when:

• Documents are largely independent (summarization tasks, independent Q&A)
• Retrieval can be solved with precise semantic search and RAG
• The question targets a known location in known documents
• Latency and cost constraints apply at scale

Frequently Asked Questions

Q: How does Gemini 2.0 Pro’s 2 million token window compare to Claude and GPT-4.1 in practice? A: At 2 million tokens, Gemini 2.0 Pro offers the largest confirmed production-accessible window among major providers as of its launch. Claude 4 Sonnet tops out at 200K tokens in standard tier (1M in limited beta), and GPT-4.1 supports 1M tokens but only via API. Real-world effective capacity across all three typically runs below advertised maximums due to context rot effects.

Q: Does performance actually hold up across 2 million tokens, or does it fall apart in the middle? A: It degrades. Gemini 1.5 Pro demonstrated >99.7% single-item recall at 1 million tokens in formal testing, but all frontier models—including Gemini—show the “lost in the middle” performance drop documented in peer-reviewed research. For complex multi-hop reasoning at extreme context lengths, expect reduced reliability compared to shorter, more curated inputs.

Q: Is Gemini 2.0 Pro available for production use? A: Gemini 2.0 Pro launched with an “Experimental” designation, available through Google AI Studio, Vertex AI, and the Gemini app for Advanced subscribers. Experimental status means SLAs, pricing, and availability are not guaranteed at the same level as GA models. Teams requiring stability for production workloads should evaluate Gemini 2.5 Pro (1M tokens, GA) or use Gemini 2.0 Pro in lower-risk workflows while monitoring Google’s GA announcements.

Q: What’s the most cost-effective way to use very long contexts? A: Context caching. If you’re running multiple queries against the same large document set—the primary use case for 2M token windows—Google’s context caching API caches the static portion and charges only for query-specific tokens on subsequent requests. Without caching, large-context queries at scale become prohibitively expensive.

Q: Should I always use the maximum context window available? A: No. Chroma Research’s context rot findings and the MIT “Lost in the Middle” study both demonstrate that precision beats volume. The right approach is the smallest context that contains the necessary information—which typically means curating inputs rather than dumping everything available. Large context windows are an escape valve for tasks that can’t be curated, not a default strategy.

Sources:

• Gemini 2.0 model updates: 2.0 Flash, Flash-Lite, Pro Experimental
• Gemini 1.5: Unlocking multimodal understanding across millions of tokens of context
• Lost in the Middle: How Language Models Use Long Contexts
• Context Rot: How Increasing Input Tokens Impacts LLM Performance
• The Needle in the Haystack Test and How Gemini Pro Solves It
• Gemini Developer API Pricing
• Gemini in Pro and long context — power file & code analysis
• Long context | Gemini API | Google AI for Developers
• Google Gemini Context Window: Token Limits, Model Comparison, and Workflow Strategies
• Revolutionising Legal Workflows: Gemini-2-Pro in Action