API Cost Lab

Last updated: October 2026 Every AI API bill comes down to one thing: tokens in, tokens out, multiplied by the price list. But the gap between "I understand the pricing page" and "I can predict my monthly invoice" is where most teams get surprised. This guide closes that gap. You'll learn what a token actually is, how the three prices on every rate card work, a formula for modeling any workload, and five practical ways to cut the bill — with real numbers throughout. What Is a Token? A token is the unit of text the model reads and writes. As a rough rule of thumb: 1 token ≈ 4 characters of English text 1 token ≈ 0.75 words So 100 tokens is roughly 75 words. A typical page of text (~500 words) is about 650–700 tokens. Why it matters: everything is metered in tokens, but you think in tasks, messages, and documents. The single most useful habit in API cost management is building an intuition for converting between the two. A few anchors: A short chat mes...

Last updated: October 2026 Two flagship models, two very different price tags — and one of the prices is about to double. If you're choosing a foundation model to build on right now, the decision isn't just about capability. It's about timing. Here's the honest comparison: what each model costs, what the benchmarks actually say, and which one to pick depending on what you're optimizing for. The Pricing: Read the Dates Gemini 4 Argon is on introductory pricing: $2.00 per 1M input tokens / $10.00 per 1M output tokens . That intro rate runs through November 30, 2026 . From December 1 , the price doubles to $4.00 / $20.00 . Muse Wonder is priced at $4.00 / $20.00 per 1M tokens — no intro period, no scheduled change. So today, Argon costs half what Wonder does. On December 1, they cost exactly the same. That convergence matters more than it looks. Every cost comparison you run today has a 6-week expiry date. If you're doing the math — and you should be — do...

Last updated: October 2026 If you're running GPT-5.6 through the API right now, you're on a promotional price. And that promotion has an expiry date: November 21, 2026 . OpenAI's pricing page states the current rate is "available at least through November 21, 2026." Read that carefully. "At least through" — not "until." The promo could extend. It could also end exactly on that date. OpenAI has published no pricing for what comes after. This post lays out exactly what the pricing is today, what it costs on a realistic workload, and how to budget for the unknown that follows November 21. The Current Pricing, Exactly GPT-5.6 is available in several variants. The one most developers are using — the flagship reasoning model, referred to here as GPT-5.6 Sol — is currently priced at: Input: $4.00 per 1M tokens Cached input: $0.40 per 1M tokens Output: $20.00 per 1M tokens That is promotional pricing. Before the promo, announced August 21, ...