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Should you fine-tune?

Name: CARTIE AI
Author: CARTIE AI

Real crossover math: monthly cost without fine-tuning vs. with, plus payback months. Jan-2026 OpenAI / Anthropic / Together AI pricing.

Model

Monthly calls

Avg prompt tokens

Avg output tokens

Few-shot savings

Training examples

Train tokens / example

Amortization (months)

Verdict

Fine-tuning would cost more — skip it

Without fine-tuning

$438

per month

With fine-tuning

$456

per month

Math breakdown

One-time training cost$5

Amortized training / month$1

Monthly savings (gross)$-18

Net monthly (post-amortization)$-19

Real fine-tuning ROI also depends on quality lift (often the bigger win) and engineering time to maintain the training pipeline. This calculator only models the pure cost crossover.

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