What is multi-model routing for AI APIs?

Multi-model routing is a cost optimization strategy where you route different types of requests to different AI models based on complexity. Simple tasks (classification, extraction, formatting) go to cheap models like GPT-4o mini or Gemini Flash. Complex tasks (reasoning, code generation, analysis) go to premium models like GPT-5 or Claude Opus. This typically saves 40-80% compared to using a single premium model for everything.

How much can I save with model routing?

Most teams save 40-80% on AI API costs by implementing model routing. For example, if 70% of your requests are simple tasks routed to a budget model ($0.15/M input) instead of a premium model ($5/M input), you save 97% on those requests. The exact savings depend on your traffic mix and which models you choose.

How do I implement model routing?

Implement model routing by: 1) Classifying incoming requests by complexity (use a cheap model or rule-based classifier), 2) Routing simple requests to budget models (GPT-4o mini, Gemini Flash, DeepSeek V4 Flash), 3) Routing complex requests to premium models (GPT-5, Claude Opus, Gemini Pro), 4) Monitoring quality and adjusting thresholds. Start with a simple 2-tier strategy and expand as you learn your traffic patterns.

Multi-Model Routing Strategy Builder

Route simple requests to cheap models, complex ones to premium. Design your routing strategy and see exactly how much you'll save.

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Total requests per month All routes combined

Avg. input tokens per request

Avg. output tokens per request

Baseline (single-model comparison) What you'd pay without routing

Routing Rules

Routing Strategy Results

Routed Cost
$0
$0.0000 per request

Single-Model Cost

$0.0000 per request

Monthly Savings
$0
0% reduction

Cost Breakdown by Route

Detailed Breakdown

Route	Model	Traffic %	Requests/Mo	Cost/Request	Monthly Cost

Annual Savings Projection

How much you'd save over 12 months with this routing strategy

ANNUAL SAVINGS

$0/yr routed vs $0/yr single-model

Routed (12 mo)

Single-model (12 mo)

What Is Multi-Model Routing?

Multi-model routing is a cost optimization strategy where you route different types of requests to different AI models based on their complexity. Instead of sending every request to an expensive premium model, you classify requests and use the cheapest model that can handle each task well.

The 3-Tier Routing Strategy

Tier 1 — Simple (60-70% of traffic): Classification, extraction, formatting, simple Q&A. Use GPT-4o mini, Gemini Flash, or DeepSeek V4 Flash ($0.075-$0.15/M input).
Tier 2 — Medium (20-30% of traffic): Summarization, translation, moderate reasoning. Use Claude Haiku, GPT-4o, or Mistral Large ($1-$2.50/M input).
Tier 3 — Complex (5-15% of traffic): Code generation, deep analysis, multi-step reasoning. Use GPT-5, Claude Opus, or Gemini Pro ($1.25-$5/M input).

How to Classify Requests

The key to model routing is accurate request classification. Common approaches:

Rule-based: Route by endpoint, user tier, or request length. Simple and fast.
Classifier model: Use a cheap model (GPT-4o mini) to classify complexity before routing. Adds ~$0.0001 per request.
Hybrid: Rules for obvious cases, classifier for ambiguous ones. Best balance of speed and accuracy.

Real-World Savings Example

A SaaS app processing 50,000 requests/month with an average of 1,200 input / 400 output tokens:

Without routing (all GPT-5): $1,125/month
With 3-tier routing: $189/month — 83% savings
Annual savings: $11,232

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