The Cost of AI Code Review: Should You Build Cheap and Review Expensive?
June 16, 2026 · 6 min read
The Split-Model Idea
A popular cost pattern in agentic coding is the build-cheap, review-expensive split: let an inexpensive model generate the bulk of the code, then have a premium model review, critique, and correct it. The logic is that generation is high-volume and forgiving, while review is where quality and judgment matter most.
It can work beautifully. It can also quietly cost more than just using the good model for everything. The difference comes down to how much output each stage produces and at what price.
Why the Split Can Save Money
Generation produces a lot of output tokens, and output is the expensive half of any bill. If a cheap model at $0.30/M output generates the first draft and a premium model at $15/M output only reads it and emits a concise critique, you've moved the high-volume work to the low-priced model and reserved the premium price for a small amount of review output.
The savings are real when review output is much smaller than generation output—a few hundred tokens of "here are the three bugs" against thousands of tokens of generated code.
Where the Math Turns Against You
The premium reviewer still has to read the generated code—those are input tokens at the premium model's input price. And if the cheap model produces buggy code that triggers multiple review-and-fix cycles, you pay for the expensive model repeatedly, plus regeneration on the cheap one. A low-quality builder can erase the savings through churn.
| Scenario | Review Cycles | Split Cost vs. All-Premium |
|---|---|---|
| Cheap model writes clean code | 1 | Much cheaper |
| Moderate quality | 2–3 | Roughly even |
| Buggy, needs heavy fixing | 4+ | More expensive |
When the Split Is Worth It
- The builder is competent: a good cheap model (DeepSeek V3, Kimi K2.7-Code) produces code the reviewer rarely has to send back.
- Review output stays small: the premium model critiques rather than rewrites.
- Tasks are well-specified: clear requirements reduce the bug rate that drives expensive churn.
If the cheap model is too weak for the task, skip the split—paying the premium model to repeatedly fix bad output is the worst of both worlds.
Bottom Line
Build-cheap, review-expensive saves money when the builder is good enough to keep review cycles low. Test your builder's quality on real tasks, then compare the two-model split against single-model cost with our AI Cost Estimator before standardizing on it.
Frequently Asked Questions
What is the build-cheap, review-expensive pattern?
Using an inexpensive model to generate most of the code, then a premium model to review and correct it. The aim is to put high-volume output on the cheap model and reserve premium pricing for a small amount of review.
When does the split-model approach save money?
When the cheap model writes clean code that needs only one review pass, and the premium model critiques concisely rather than rewriting. Savings come from moving high-volume output to the low-priced model.
When does it cost more than just using one good model?
When the cheap model produces buggy code that triggers multiple review-and-fix cycles. The premium model is paid repeatedly to read and re-review, plus regeneration cost on the cheap model, which can exceed all-premium cost.
Want to calculate exact costs for your project?
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