Which Claude 3 Model Should You Use? Complete Decision Guide

A month into the Claude 3 release, the most common question we hear from operations teams is simple: which model should I actually use? The answer isn't straightforward. Anthropic released three models precisely because different tasks have different requirements. The key is matching the model to the task. This guide gives you a practical framework for making that decision. ## The Core Tradeoffs Every Claude 3 model represents a different balance of four factors: **Intelligence:** How capable is the model at complex reasoning, nuanced understanding, and difficult tasks? **Speed:** How quickly does it respond? How many tasks can it process per hour? **Cost:** What's the price per task at realistic usage volumes? **Accuracy:** How often does it produce correct, reliable outputs? You can't optimize for everything simultaneously. The art is knowing which factors matter most for each task. ## The Decision Framework Use this four-question framework to choose your model: ### 1. What's the Complexity Level? **Simple/Structured Tasks:** Clear patterns, straightforward logic, well-defined outputs. - Examples: FAQ responses, data extraction, content classification, template filling - **Choose: Haiku** **Medium Complexity:** Requires understanding context, some reasoning, business judgment. - Examples: Business writing, meeting summaries, analysis, customer communication - **Choose: Sonnet** **High Complexity:** Multi-step reasoning, expert knowledge, nuanced judgment, strategic thinking. - Examples: Strategic planning, legal analysis, technical architecture, research synthesis - **Choose: Opus** ### 2. What's the Volume? **High Volume (100+ per day):** - Cost becomes primary concern - Speed affects throughput - **Bias toward: Haiku or Sonnet** **Medium Volume (10-100 per day):** - Balance cost and quality - Speed less critical - **Bias toward: Sonnet** **Low Volume (1-10 per day):** - Quality matters most - Cost difference is negligible - **Bias toward: Opus or Sonnet** ### 3. What's the Cost of Errors? **High Cost (legal, financial, strategic decisions):** - Accuracy is non-negotiable - Worth paying premium for reliability - **Choose: Opus** **Medium Cost (customer-facing, internal operations):** - Errors are fixable but annoying - Human review catches most issues - **Choose: Sonnet** **Low Cost (internal drafts, high-volume screening):** - Errors are easy to catch and fix - Speed/cost more important than perfection - **Choose: Haiku** ### 4. Is Speed Critical? **Real-Time Applications:** - User-facing chat - Interactive tools - Live customer support - **Choose: Haiku** **Batch Processing:** - Overnight jobs - Scheduled reports - Background analysis - **Choose: Opus or Sonnet based on complexity** **Standard Workflows:** - Response time under 30 seconds is fine - **Any model works, choose based on other factors** ## Task-Specific Recommendations Here's how to choose for common business operations tasks: ### Strategic Planning & Analysis **Model: Opus** **Why:** Requires maximum intelligence, multi-step reasoning, and nuanced judgment. Errors in strategic decisions are costly. Low volume means cost is manageable. **Examples:** - Annual business planning - Competitive strategy - Market entry analysis - M&A evaluation - Technical architecture decisions **Cost per task:** $0.15-0.30 for complex analysis ### Business Writing **Model: Sonnet** **Why:** Requires good writing quality and business context but not maximum intelligence. Medium volume means cost efficiency matters. Humans review before sending. **Examples:** - Proposals and reports - Internal documentation - Executive summaries - Email communications - Presentation content **Cost per task:** $0.02-0.05 per document ### Customer Support **Model: Haiku (with Sonnet for complex cases)** **Why:** High volume makes cost critical. Speed improves response times. Most questions follow patterns. Human agents review before sending. **Examples:** - FAQ responses - Troubleshooting steps - Account questions - Feature explanations **Cost per task:** $0.001-0.003 per response **Smart approach:** Use Haiku for initial draft, route complex cases to Sonnet. ### Contract & Legal Review **Model: Opus** **Why:** Errors are expensive. Requires nuanced interpretation and attention to detail. Low to medium volume. **Examples:** - Vendor agreements - Employment contracts - Partnership terms - Compliance review **Cost per task:** $0.50-2.00 per contract (worth it for accuracy) ### Data Extraction & Processing **Model: Haiku (Sonnet for complex formats)** **Why:** High volume, structured output, clear patterns. Speed affects throughput. Errors are easy to spot. **Examples:** - Invoice processing - Form extraction - Database population - Receipt parsing **Cost per task:** $0.0005-0.002 per document ### Meeting Summaries **Model: Sonnet** **Why:** Requires understanding context and identifying important points. Medium volume. Quality matters but not critical. **Examples:** - Team meetings - Client calls - 1-on-1s - Standup notes **Cost per task:** $0.01-0.03 per meeting ### Code Generation **Model: Opus for complex, Sonnet for standard, Haiku for simple** **Why:** Complexity varies dramatically. Complex code needs Opus (84.9% HumanEval). Standard CRUD operations work fine with Sonnet. Script automation can use Haiku. **Examples:** - **Opus:** Algorithm design, system architecture, complex debugging - **Sonnet:** API integrations, data processing, standard features - **Haiku:** Simple scripts, config generation, boilerplate code ### Financial Analysis **Model: Opus** **Why:** Accuracy is critical. Numbers must be correct. Requires understanding financial concepts and business context. **Examples:** - Budget analysis - Financial modeling - Variance reporting - Investment analysis **Cost per task:** $0.10-0.50 per analysis ### Research & Synthesis **Model: Opus (Sonnet for straightforward topics)** **Why:** Requires deep understanding, connecting disparate information, identifying patterns. Medium complexity topics work with Sonnet. **Examples:** - **Opus:** Technical research, competitive intelligence, academic synthesis - **Sonnet:** Industry trends, news summaries, basic research ### Content Moderation **Model: Haiku** **Why:** High volume, clear policies, structured decisions. Speed enables real-time moderation. Humans review edge cases. **Examples:** - User content review - Comment filtering - Policy enforcement - Spam detection **Cost per task:** $0.0003-0.001 per item ## Model Routing Strategy The most cost-effective approach uses all three models: ### Tier 1: Haiku (High Volume, Low Complexity) 60-70% of tasks: - Customer support drafts - Data extraction - Content moderation - Simple classifications ### Tier 2: Sonnet (Daily Work, Medium Complexity) 25-35% of tasks: - Business writing - Meeting summaries - Analysis and reporting - Standard code generation ### Tier 3: Opus (Complex, Critical Tasks) 5-10% of tasks: - Strategic planning - Legal review - Complex coding - Financial analysis This routing can reduce costs by 70-80% compared to using Opus for everything, while maintaining quality where it matters. ## Cost Analysis by Team Size ### Small Team (5-10 people) **Scenario:** Mixed workload of writing, analysis, customer support **Smart distribution:** - 100 Haiku tasks/day (support, extraction): $3/day - 20 Sonnet tasks/day (writing, summaries): $1/day - 3 Opus tasks/day (complex analysis): $0.50/day **Monthly cost:** ~$135 **All-Opus cost:** ~$1,500/month **Savings:** $1,365/month (91% reduction) ### Medium Team (25-50 people) **Scenario:** Operations, customer support, analysis **Smart distribution:** - 500 Haiku tasks/day: $15/day - 100 Sonnet tasks/day: $5/day - 10 Opus tasks/day: $2/day **Monthly cost:** ~$660 **All-Opus cost:** ~$9,000/month **Savings:** $8,340/month (93% reduction) ### Large Team (100+ people) **Scenario:** Enterprise operations with high volume **Smart distribution:** - 2,000 Haiku tasks/day: $60/day - 400 Sonnet tasks/day: $20/day - 40 Opus tasks/day: $8/day **Monthly cost:** ~$2,640 **All-Opus cost:** ~$36,000/month **Savings:** $33,360/month (93% reduction) ## Quick Decision Matrix **Choose Opus if ANY of these are true:** - Errors would cost >$100 - Requires expert-level reasoning - Strategic/critical decision - Complex technical work - Legal or financial content **Choose Haiku if ALL of these are true:** - Task follows clear patterns - Processing >50 per day - Speed matters - Errors are easy to catch - Human reviews outputs **Choose Sonnet for everything else.** When in doubt, start with Sonnet. It handles 80% of business tasks well. ## Quick Takeaway Choose your Claude 3 model based on task complexity, volume, error cost, and speed requirements. Use Opus for complex reasoning and critical decisions. Use Sonnet for daily knowledge work and business operations. Use Haiku for high-volume, structured tasks. The most cost-effective strategy routes tasks across all three models based on requirements, reducing costs by 70-90% while maintaining quality where it matters.