I’ve done that. Even when OpenAI hadn’t and still doesn’t (they finally added GPT-5.2 to their own calculator, for which you can input a resolution and still get a different token count than billed, after a month of mystery pricing to truly be reverse-engineered).
You can pull the truth table and even resizing algorithms and multiplying of costs out of the script.
Compare quickly
Oh, and over here is Python table with some of those facts: which models support vision, their vision algorithm, cost multiplier and cost per tile. Even endpoint it can run on and the token overhead per message and per call.