Beating the Best Model

Save costs without losing quality. Auto Router delivers best-model accuracy at a fraction of the price.

Most developers assume that using the best model is the safest bet for every query. But in practice, that often means paying more than you need to — especially when cheaper models can handle simpler queries just as well.

LangDB’s Auto Router shows you don’t always need the “best” model — just the right model for the job.

The Question We Asked

When building AI applications, you face a constant trade-off: performance vs. cost. Do you always use the most powerful (and expensive) model to guarantee quality? Or do you risk cheaper alternatives that might fall short on complex tasks?

We wanted to find out: Can smart routing beat the "always use the best model" strategy?

Our Experiment

We designed a head-to-head comparison using 100 real-world queries across four domains: Finance, Writing, Science/Math, and Coding. Each query was tested against two strategies:

• Auto Router → Analyzed query complexity and topic, then selected the most cost-effective model that could handle the task

• Router:Accuracy → Always defaulted to the highest-performing model (the "best model" approach)

What made this test realistic:

• Diverse complexity: 70 low-complexity queries (simple conversions, definitions) and 30 high-complexity queries (complex analysis, multi-step reasoning)

• Real-world domains: Finance calculations, professional writing, scientific explanations, and coding problems

• Impartial judging: Used GPT-5-mini as an objective judge to compare response quality

Sample of what we tested:

• Finance: "A company has revenue of $200M and expenses of $150M. What is its profit?"

• Writing: "Write a one-line professional email subject requesting a meeting"

• Science/Math: "Convert 100 cm into meters"

• Coding: "Explain what a variable is in programming in one sentence"

Results

Metric	Auto Router	Router:Accuracy
Total Cost	$0.95	$1.64
Wins	65%	0%
Ties	35%	35%
Losses	0%	0%
Accuracy Parity	100% (wins + ties)	100%

What Wins & Ties Mean

• Win → Auto Router chose a cheaper model, and the output was equal or better than the best model.

• Tie → Auto Router escalated to the best model itself, because the query was complex enough to require it.

• Loss → Didn’t happen. Auto Router never underperformed compared to always using the best model.

In other words: Auto Router matched or beat the best model strategy 100% of the time — while cutting costs by ~42%.

Category Breakdown

Category	Count	Router Wins	Ties (Used Best Model)
Finance	25	23	2
Writing	24	18	6
Science & Math	19	14	5
Coding	32	10	22

• In Finance and Writing, Auto Router confidently used cheaper models most of the time.

• In Coding, Auto Router often escalated to the best model — proving it knows when not to compromise.

The Methodology Behind the Magic

How Auto Router Works: Auto Router doesn't just pick models randomly. It uses a sophisticated classification system that:

1. Analyzes query complexity — Is this a simple fact lookup or a complex reasoning task?

2. Identifies the domain — Finance, writing, coding, or science/math?

3. Matches to optimal model — Selects the most cost-effective model that can handle the specific complexity level

The "Always Best" Approach: Router:Accuracy takes the conservative route — always selecting the highest-performing model regardless of query complexity. It's like using a Formula 1 car for grocery shopping.

Fair Comparison: We used GPT-5-mini as an impartial judge to evaluate response quality across both strategies. The judge compared answers based on correctness, usefulness, and completeness without knowing which routing strategy was used.

What This Means for Developers

The Real-World Impact:

• Cost optimization without compromise — Save 42% on API costs while maintaining quality

• Intelligent escalation — Complex queries automatically get the best models

• No manual tuning — The router handles the complexity analysis for you

Try It Yourself

Using Auto Router is simple — just point to router/auto:

{
  "model": "router/auto",
  "messages": [
    {
      "role": "user",
      "content": "A company has revenue of $200M and expenses of $150M. What is its profit?"
    }
  ]
}

Auto Router will automatically select the most cost-effective model that can handle your query complexity.

The Bottom Line

• Save Money → Auto Router avoids overpaying on simple queries

• Stay Accurate → For complex cases, it automatically picks the strongest model

• Smarter Than "Always Best" → Matches or beats the best-model-only approach at a fraction of the cost

Takeaway

You don't need to pick the "best" model every time.

With Auto Router:

• Simple queries → cheaper models save you money

• Complex queries → stronger models keep accuracy intact

• Overall → 100% accuracy parity at 42% lower cost

That's the power of LangDB Auto Router.