# Blockbrain LLM Selection Guide

### How Blockbrain Measures Usage 

Every action on Blockbrain - messages, file uploads, or agent runs - consumes Compute Blocks (CBs), a transparent, usage-based metric reflecting the actual computational cost of each operation. CBs are primarily driven by LLM token usage, and their consumption directly mirrors each model's input/output token pricing. 

> **A more expensive model = proportionally higher CB usage.** 

### Default Recommendation 

| Model                           | Quality | Speed | Cost Eff. | Pricing (Input/Output per 1M tokens) |
| ------------------------------- | ------- | ----- | --------- | ------------------------------------ |
| Gemini 2.5 Flash                | 4.3     | 4.8   | 4.6       | $0.50 / $3.00                        |
| GPT 5.4 Mini (budget alt.)      | 4.3     | 4.5   | 4.2       | $0.40 / $1.60                        |
| Claude Haiku 4.5 (quality alt.) | 4.2     | 3.6   | 4.0       | $1.00 / $5.00                        |

>  **Gemini 2.5 Flash** is the best all-around choice — excellent quality, fast, cost-efficient, with a 1M token context window. 

### Quick Decision Matrix 

| Priority           | Primary Pick                    | Budget Option                   | Premium Option          |
| ------------------ | ------------------------------- | ------------------------------- | ----------------------- |
| Everyday use       | Gemini 2.5 Flash                | GPT 5.4 Mini                    | Gemini 2.5 Pro ($2/$12) |
| Max cost savings   | GPT 4o Mini ($0.15/$0.60)       | GPT 5.4 Mini                    | Gemini 2.5 Flash        |
| Highest quality    | Claude Opus 4.6 Max ($5/$25)    | Gemini 2.5 Pro                  | GPT 5.5 Pro ($5/$30)    |
| Fastest response   | Claude Sonnet 4.6 Fast ($3/$15) | Gemini 2.5 Flash                | GPT 5.4 Low Thinking    |
| Creative & writing | Claude Sonnet 4.6 ($3/$15)      | Claude Haiku 4.5                | Claude Opus 4.6         |
| Code development   | GPT 5.3 Codex ($1.75/$14)       | Mistral Codestral ($0.30/$0.90) | Claude Opus 4.6         |
| Complex reasoning  | o3 ($2/$8)                      | o4 Mini ($1.10/$4.40)           | GPT 5.5 Pro             |

### Key Considerations 

* **Output tokens cost more than input tokens** - prioritize low output-cost models for reports, docs, and code generation. 
* **1M context windows** (Gemini 2.5 Flash/Pro, Claude Sonnet 4.6) hold \~3,000 pages of text - critical for document analysis and long conversations. 
* **Premium models add up fast**: 1,000 queries cost \~$0.68 with GPT 5.4 Mini vs. \~$10.00 with Claude Opus 4.6. 


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