Grok Build 0.1 vs Grok 4.20 (Reasoning)
Benchmarks, API Token Pricing, Context Window & Speed Comparison
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Grok Build 0.1 by xAI and Grok 4.20 (Reasoning) by xAI represent two of the frontier AI models analyzed in our comprehensive 2026 AI benchmark and LLM comparison. In this head-to-head evaluation, we examine API token pricing, context window specifications, inference speed (tokens per second), and empirical reasoning performance. From a pure economic perspective, Grok Build 0.1 holds a notable pricing advantage for token ingestion. On output generation, Grok Build 0.1 is more economical per million generated tokens. In data-heavy architectures requiring extensive repository or document analysis, Grok 4.20 (Reasoning) provides an expanded memory horizon with 1,000K tokens. In latency-sensitive production environments, Grok Build 0.1 leads in tokens-per-second throughput, making it ideal for real-time conversational agents and high-concurrency workflows. Below is the complete empirical head-to-head breakdown across cost, speed, context, and capability matrices.
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Grok Build 0.1
Agentic CodingFast specialized Grok coding engine engineered for iterative code edits, refactoring, and agentic engineering workflows.
$1.00 / 1M
$2.00 / 1M
256K tokens
69.8%
Grok 4.20 (Reasoning)
Document AnalysisxAI's reasoning model engineered for heavy document analysis, complex logic deduction, and long-horizon agentic tool use.
$3.00 / 1M
$15.00 / 1M
1M tokens
68.2%
Key Differences at a Glance
- Grok Build 0.1 is 5.2x cheaper for API usage (input + output tokens combined).
- Grok 4.20 (Reasoning) has a larger context window (1M vs 256K tokens).
- Grok Build 0.1 is faster at 120 tok/s vs 95 tok/s.
- Grok Build 0.1 leads on SWE-bench coding (69.8% vs 68.2%).
| Feature | Grok Build 0.1 | Grok 4.20 (Reasoning) |
|---|---|---|
Intelligence Index Composite reasoning & knowledge score (0-100) | 65 | 68 |
Provider | xAI | xAI |
Input Price Cost per million input tokens | $1.00 / 1M | $3.00 / 1M |
Output Price Cost per million output tokens | $2.00 / 1M | $15.00 / 1M |
Blended Price Weighted 7:2:1 cache:input:output per 1M | $0.57 / 1M | $2.63 / 1M |
Context Window Maximum input + output tokens | 256K tokens~384 A4 pages of text | 1M tokens~1,500 A4 pages of text |
Max Output Tokens Per single request | 66K | 66K |
Throughput Speed Tokens generated per second | 120 tok/s | 95 tok/s |
SWE-bench Verified Real-world software engineering | 69.8% | 68.2% |
GPQA Diamond Graduate-level reasoning | 68.2% | 72.8% |
Cached Input Price Prompt caching discount per 1M tokens | $0.25 / 1M | $0.75 / 1M |
Who Wins Where?
At-a-glance decision frameworkEmpirical Head-to-Head Benchmark Scores
Official evaluation metrics verified by independent third-party research labs.
Industry benchmark evaluating real-world GitHub issue resolution and multi-file debugging.
Challenging questions created by domain experts to test complex PhD-level reasoning.
Hardened reasoning and academic knowledge benchmark with reduced lucky-guess probability.
Crowdsourced human preference evaluation based on blind, head-to-head model battles.
Extremely difficult, closed-ended questions spanning the frontier of human expert knowledge.
Autonomous multi-step tasks executed inside a real command-line terminal environment.
Research-grade coding problems drawn from real scientific and numerical workloads.
Contamination-free competitive programming problems collected continuously over time.
American Invitational Mathematics Examination — multi-step Olympiad-level reasoning.
Accuracy when reasoning over very large inputs that fill the model context window.
Tokens emitted per second during active generation streaming.
Latency & Response Time
Time to first token (TTFT) and estimated end-to-end response time for a typical 500-token response.
Real-Time Interactive Token Cost Simulator
Adjust sliders to calculate projected monthly cloud API spending with prompt caching discounts.
Grok Build 0.1 · Strengths & Key Advantages
- Ultra-responsive iterative code generation with exceptional diff accuracy
- Autonomous agentic tool calling optimized for IDE, CLI, and terminal environments
- Strong 94.6% HumanEval score and competitive SWE-bench coding benchmarks
Considerations & Trade-offs
- Experimental preview release with occasional syntax edge-case variations
- Context window limited to 256K tokens compared to 1M in flagship Grok variants
Grok 4.20 (Reasoning) · Strengths & Key Advantages
- Expansive 1M-token context window tailored for dense repository and legal document intake
- Robust multi-step chain-of-thought reasoning with persistent long-horizon tool execution
- Multimodal ingestion across technical diagrams, multi-page PDFs, and complex charts
- Direct real-time knowledge synthesis from xAI Colossus cluster
Considerations & Trade-offs
- Outperformed by Grok 4.7 and late-2026 frontier leaders on competitive coding benchmarks
- Higher output latency during extended chain-of-thought generation cycles
Token Use & Task Economics
Estimated cost and token consumption to complete one representative agentic task.
| Metric | Grok Build 0.1 | Grok 4.20 (Reasoning) |
|---|---|---|
Cost per Task Estimated USD to finish one task | $0.95 | $1.45 |
Output Tokens / Task Tokens generated per task | 42K | 45K |
Reasoning Tokens / Task Thinking tokens burned per task | 18K | 28K |
Technical Specifications
Architecture, release timeline, capabilities, and modalities.
| Feature | Grok Build 0.1 | Grok 4.20 (Reasoning) |
|---|---|---|
| Official API Model ID (SDK) | grok-build-0-1-latest | grok-4-20-reasoning-latest |
| API Protocol | xAI REST API (OpenAI-Compatible) | xAI REST API (OpenAI-Compatible) |
| Release Date | 2026-04 | 2026-03 |
| Knowledge Cutoff | January 2026 | November 2025 |
| Architecture | Code-Specialized Autoregressive Transformer | Colossus-Scale Reasoning Sparse MoE |
| Parameters | Confidential | Confidential |
| Enterprise Rate Limits (RPM / TPM) | 5,000 – 15,000 RPM (Production Tier) · 800,000 – 2,000,000 TPM | 5,000 – 15,000 RPM (Production Tier) · 4,000,000 – 10,000,000 TPM |
| Long-Context Tier (>128K/200K) | Flat rate ($1/1M in) across full 256K window | Flat rate ($3/1M in) across full 1000K window |
| Prompt Cache Policy & TTL | Cached input at $0.25/1M tokens | Cached input at $0.75/1M tokens |
| Computer Use / GUI Agent | API / CLI Tool-Use & DOM Agent ready (no raw pixel desktop click loop) | API / CLI Tool-Use & DOM Agent ready (no raw pixel desktop click loop) |
| MCP & Parallel Tool Calling | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema |
| Web Search Grounding & Sandbox | Real-time Web & X (Twitter) Search Grounding + Code Execution | Real-time Web & X (Twitter) Search Grounding + Code Execution |
| Official Fine-Tuning Support | API Prompt Engineering & RAG Distillation | API Prompt Engineering & RAG Distillation |
| Multimodal Token Billing | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) |
| Quantization & Min GPU VRAM | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) | Cloud-Hosted Proprietary (FP8 / BF16 Tensor Core Cluster) · Zero Local VRAM Required (100% Serverless Cloud API) |
| Safety & Frontier Classification | xAI Production Safety & Alignment Verified | xAI Production Safety & Alignment Verified |
| Enterprise Compliance (ZDR/HIPAA/SOC2) | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier | SOC2 Type II · GDPR · Zero Data Retention (ZDR) & HIPAA BAA Available on Enterprise Tier |
| Input Modalities | text, vision | text, vision |
| Output Modalities | text | text |
Grok Build 0.1 vs Grok 4.20 (Reasoning): Quick Answers
Which is more intelligent, Grok Build 0.1 or Grok 4.20 (Reasoning)?
Grok 4.20 (Reasoning) is more intelligent. It scores 68 compared with 65 on the composite Intelligence Index.
Which model is faster?
Grok Build 0.1 is faster, generating 120 tokens per second compared with 95 tokens per second.
Which model is cheaper to run?
Grok Build 0.1 is cheaper at $0.57 per 1M tokens blended, compared with $2.63 (7:2:1 cache:input:output ratio).
Which model has lower latency?
Grok Build 0.1 has lower latency, with a time to first token of 0.55s compared with 0.98s.
Which model has a larger context window?
Grok 4.20 (Reasoning) has a larger context window, supporting 1M tokens compared with 256K tokens.
Verdict
Verdict & Model Selection Recommendation: Choose Grok Build 0.1 if your priority is IDE copilots, automated PR review agents, and rapid iterative software prototyping. Its performance in demanding tasks justifies its operational token cost. Choose Grok 4.20 (Reasoning) if your workflow prioritizes Deep document analysis, multi-stage enterprise research, and extensive tool-driven workflows. For large-scale batch processing or customer-facing conversational interfaces, its balance of speed and economics delivers superior ROI.
Frequently asked questions
How does Grok Build 0.1 compare to Grok 4.20 (Reasoning) in API token pricing and cost per token?+
Grok Build 0.1 costs $1.00 per 1M input tokens and $2.00 per 1M output tokens, whereas Grok 4.20 (Reasoning) costs $3.00 input and $15.00 output. Overall, Grok Build 0.1 is the more cost-effective model for high-volume API pipelines. Both models support prompt caching discounts of up to 90% for repeated prompt prefixes.
Which model has a larger context window: Grok Build 0.1 or Grok 4.20 (Reasoning)?+
Grok Build 0.1 supports a context window of 256K tokens (~192k words), while Grok 4.20 (Reasoning) supports 1,000K tokens (~750k words). Therefore, Grok 4.20 (Reasoning) can process more textual data and document context in a single prompt.
Which AI model is better for software engineering and coding: Grok Build 0.1 or Grok 4.20 (Reasoning)?+
Grok Build 0.1 scores 69.8% on SWE-bench Verified while Grok 4.20 (Reasoning) scores 68.2%. For autonomous software engineering and multi-file debugging, Grok Build 0.1 holds the verified benchmark lead.
What is the difference in reasoning capability and extended thinking between Grok Build 0.1 and Grok 4.20 (Reasoning)?+
Grok Build 0.1 features native chain-of-thought extended thinking mode with configurable reasoning effort. In contrast, Grok 4.20 (Reasoning) provides chain-of-thought reasoning depth for complex math and science.
How does inference speed (tokens per second) compare between Grok Build 0.1 and Grok 4.20 (Reasoning)?+
Grok Build 0.1 generates approximately 120 tokens per second, while Grok 4.20 (Reasoning) delivers 95 tokens per second. In latency-sensitive production environments, Grok Build 0.1 provides faster time-to-first-token (TTFT) and higher streaming response velocity.
Can you implement a tiered LLM routing setup combining Grok Build 0.1 and Grok 4.20 (Reasoning) to optimize costs?+
Yes! High-efficiency architectures route high-frequency routine classification and conversational tasks to Grok Build 0.1 to save operational costs, and dynamically escalate complex architectural queries or reasoning tasks to Grok 4.20 (Reasoning). This tiered routing pattern cuts overall API bills by up to 70%.
Understand key metrics like context window, token pricing, reasoning mode, and SWE-bench scores in our comprehensive AI glossary.
Related reading
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Benchmark scores, token prices, and rate limits evolve rapidly as AI labs release model updates. Always verify current specifications and pricing on the official provider documentation.
Sources: GetInfoUs Independent AI Benchmarks & Official API Specs