The 272K Long-Context Cliff, Fully Specified

Every model that publishes this rule applies it the same way: once a request's input crosses the threshold — 272,000 tokens — the entire request reprices, input and output both, not just the portion past the line.

Why "full request" is the detail that trips people up

Most tiered pricing works like a tax bracket, with the higher rate applying only to the amount over the threshold. This rule doesn't. Cross the line by one token and every token in that request bills on the long-context band. Treating it like a bracket understates the cost of every request that crosses it.

The wording differs by family; the bands don't

GPT-6 model pages say the rule applies 2x to "input and cache rates" and 1.5x to output. GPT-5.6 pages name only input and output, and GPT-5.5 and GPT-5.4 pages say the rule covers "the full session for standard, batch, and flex." Read the published long bands rather than the sentences and the pattern is consistent: wherever a long band exists, cached-input and cache-write cells rise by the same multiplier as input. Since August, GPT-5.6 models also publish long-context Fast bands; GPT-5.5 and GPT-5.4 still don't.

Not every model publishes it

This page once said the rule was absent from smaller models because their windows sit under the threshold. That was wrong: GPT-5.4 Mini, GPT-5.4 Nano and GPT-5.3 Codex all have windows larger than the threshold. Their pages simply don't state a rule, and the pricing page carries no long band for them — so this site models no cliff for them rather than assuming one. GPT-5.5 Pro has a published long Standard band but no rule sentence on its page; it gets the same caution.

Why this bites agentic work

A single prompt rarely nears the threshold. A long agentic session, re-sending accumulated files and prior turns every turn, crosses it as a side effect of ordinary operation — usually without anyone sending a deliberately "large" request.

The table above shows every priced model's rule and its Standard long-context band.