# Cascade Routing: Cut Your API Costs by 66% | Agentic Engineering the Hard Way
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# Cascade Routing: Cut Your API Costs by 66% ​

June 11, 2026

Most teams use one model for everything. They default to Claude Opus or GPT-5 for every task, which means they are paying premium prices for simple work.

## The Price Range ​

Model | Input ($/M) | Output ($/M)
--- | --- | ---
Gemini 2.5 Flash | $0.15 | $0.60
DeepSeek V3 | $0.27 | $1.10
Claude Sonnet 4 | $3.00 | $15.00
Claude Opus 4 | $15.00 | $75.00

That is a 100x range between the cheapest and most expensive.

## The Cascade Pattern ​

Route different steps to different models. Use cheap models for simple retrieval and formatting. Use expensive models only for complex reasoning.

    Retrieve context -> Gemini Flash ($0.15/$0.60)
    Analyze data     -> Claude Sonnet ($3/$15)
    Make decision    -> Claude Opus ($15/$75)
    Format output    -> Gemini Flash ($0.15/$0.60)

## The Savings ​

Pattern | Cost/Task | Savings
--- | --- | ---
All Opus | $2.50 | Baseline
Cascade | $0.85 | 66%
All Sonnet | $0.50 | 80% (but quality loss on complex steps)

## Implementation ​

python

    def route_task(task_complexity: str) -> str:
        if task_complexity == "retrieval":
            return "gemini-2.5-flash"
        elif task_complexity == "analysis":
            return "claude-sonnet-4"
        elif task_complexity == "decision":
            return "claude-opus-4"
        elif task_complexity == "formatting":
            return "gemini-2.5-flash"

## When Not to Cascade ​

If your task is a single critical decision, use the best model. Cascade routing shines when you have a pipeline of steps with varying complexity, which is most real-world agent systems.

From Module 6 of the Agentic Engineering Course. The full module includes a cost optimization lab with working code.