GPT-5 API cost calculator
GPT-5 (OpenAI) is priced at $1.25 per million input tokens, $0.125 for cached input, and $10 per million output tokens — half that through the Batch API. Verified 2026-09-17 against OpenAI's pricing page.
What GPT-5 costs for common workloads
| Workload | Per request | Per day | Per month |
|---|---|---|---|
| Support chatbotShort turns with a reused system prompt — 3k in, 400 out, 60% cached. | $0.0057 | $28.63 | $859 |
| RAG over documentsRetrieved context dominates — 12k in, 500 out, 30% cached. | $0.016 | $23.92 | $718 |
| Coding agentGrowing context every turn — 20k in, 1.5k out, 80% cached. | $0.022 | $66.00 | $1,980 |
| Batch classificationTiny prompts at volume through the Batch API — 800 in, 20 out. | $0.0006 | $120 | $3,600 |
Its blast radius when an agent loops
The coding-agent workload above at 30 requests a minute — $39.60 an hour — priced at each point a team usually finds out:
Hourly alert
$39.60
Next morning
$950
After a weekend
$2,376
Monthly invoice
$28,512