A per-call price lies about agents. A loop re-sends its whole context every turn, so input scales with the square of the step count. See what a run really costs — and how much prefix caching claws back.
$0.5078/run × 10,000 = $5,078/mo with prefix caching. The same 20-step loop with no caching is $21,750/mo — because re-sending a growing context makes raw input scale with the square of the turn count (70% of it is that N² term). Caching is what keeps agent cost near-linear.
The LLM cost calculator prices one independent request. An agent is not one request — it is a loop of many, and each turn re-sends the entire conversation so far: the fixed prefix (system prompt + tool schemas) plus everything the loop has appended. Turn t therefore reads base + (t−1)·growth tokens, and summed across an N-step run the input is N·base + growth·N(N−1)/2. That second term is quadratic in the step count — double the turns and the raw input bill roughly quadruples. It is the cost that ambushes teams who budgeted from a per-call price, and the reasoning is laid out in why AI agent costs scale quadratically.
Prefix caching is the escape hatch. Because each turn's prefix is byte-identical to the previous turn's, it bills as a cache read at roughly a tenth of the input rate, and only the newly appended slice — about growth tokens — is fresh. That pulls the quadratic term back toward linear: fresh input across the run is only base + (N−1)·growth. The gap between the two numbers this page shows is the entire return on turning caching on for an agentic workload; the mechanics are in prompt caching for AI agents. Caching only helps while the prefix stays stable, which is also the argument against rewriting context mid-run — every edit upstream invalidates the cache below it.
The defaults are illustrative order-of-magnitude figures; every field is editable, including the list prices (a June 2026 snapshot). Sizing the window those turns consume instead? See the context-window budget calculator. Serving the model yourself? The VRAM calculator covers the hardware side.
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