# GPT-5.4 Pro pricing, and the missing cached rate

> GPT-5.4 Pro and GPT-5.5 Pro both bill $30 per million input and $180 output, with no cached rate. What that means for repeated prompts.

URL: https://getculpa.com/gpt-5-4-pro-pricing
Last reviewed: 2026-08-01
Rates effective: 2026-07-02

## Answer
GPT-5.4 Pro pricing is $30.00 per million input tokens and $180.00 per million output tokens, and GPT-5.5 Pro bills identically. Neither carries a cached rate, so a repeated system prompt pays full price every call. Culpa, a local-first LLM cost, margin, and forecast ledger, meters the repeated share of your input so that cost stops being invisible.

## Why this happens
Two things make the Pro tier behave differently from everything else on the roster. It's twelve times GPT-5.4 on input and twelve times on output, so the usual intuitions about rounding errors stop applying. And this price book records no cached input rate for either Pro model, which removes the one lever that normally rescues a long repeated prompt. On Pro, prompt length is paid in full, forever.

## What this usually looks like
- A handful of Pro calls outspend thousands of calls on your production model.
- Your Pro-tier feature sends the same long system prompt every call, with no discount available.
- Evaluation or final-pass work quietly runs on Pro because it was the best model when it was written.
- One Pro conversation appears in your top spenders despite a tiny call count.

## Common mistakes
- Carrying a long system prompt onto Pro calls. Why it hurts: With no cached rate, every repeated token bills at $30 per million on every single call. Do instead: Strip the Pro prompt to what the Pro step genuinely needs, and keep the long version on cheaper tiers.
- Letting Pro produce long-form output without a cap. Why it hurts: At $180 per million, a thousand extra output tokens costs eighteen cents on a single call. Do instead: Set a hard max-tokens ceiling on Pro calls and treat hitting it as a signal to reshape the task.
- Leaving Pro in a retry path. Why it hurts: A retried Pro call is the most expensive single event your system can produce. Do instead: Never escalate retries to Pro automatically. Make it an explicit, logged decision.

## Self-check
- Count your Pro calls this month and price them individually. The list is usually short and startling.
- Measure how many tokens of each Pro prompt are identical across calls. That block has no discount available.
- Check whether any retry or fallback path can reach a Pro model.
- Compare your total Pro spend to your total production-model spend at a fraction of the call count.
- Confirm each Pro call is doing work that genuinely needs it, rather than work inherited from an older design.

## Twelve times the rate, and no cache to soften it (illustrative)
A final-pass step on GPT-5.4 Pro running 2,000 times a month. Each call sends a 4,000-token prompt, of which 3,000 tokens are an identical system block, and returns 1,200 tokens.
  Input: 2,000 x 4,000 = 8M tokens x $30.00 per million = $240.00
  Output: 2,000 x 1,200 = 2.4M tokens x $180.00 per million = $432.00
  Month total = $672.00 across just 2,000 calls, so $0.336 per call
  The repeated 3,000-token block alone: 6M x $30.00 per million = $180.00, with no cached rate to reduce it
  The same 2,000 calls on GPT-5.4 = (8 x $2.50) + (2.4 x $15.00) = $20 + $36 = $56
$672 for 2,000 calls against $56 on GPT-5.4, and $180 of it's a repeated prompt block that no cache can discount. On this tier prompt length is a permanent cost.

## Cost figures
Every figure carries its confidence and its source. No figure on this site is provider-reported.
- $30.00 / $180.00 per million — GPT-5.4 Pro and GPT-5.5 Pro input and output rates, identical on both models [calculated] Source: Culpa price book rows for openai/gpt-5.4-pro and openai/gpt-5.5-pro, both $0.030 and $0.180 per 1k, effective 2026-07-02, verified against OpenAI API pricing.
- 12x — Pro tier cost as a multiple of GPT-5.4 on both input and output [calculated] Source: $30.00 / $2.50 and $180.00 / $15.00, from the price-book rows.

## FAQ
Q: Do GPT-5.4 Pro and GPT-5.5 Pro cost the same?
A: Yes. Both bill $30.00 per million input and $180.00 per million output in this price book, verified 2026-07-02. Since the rate is identical, the choice between them is a capability question rather than a cost one.

Q: Why does the Pro tier have no cached rate?
A: This price book records none for either Pro model. The practical consequence matters more than the reason: a repeated system prompt that would cost a tenth on a cached tier costs full price here, on every call.

Q: How do I keep Pro spend bounded?
A: Cap max tokens, strip the prompt to what the step needs, and make sure no retry or fallback path can reach Pro automatically. A single escalated Pro retry is the most expensive event most systems can generate.

## Sources
- OpenAI API pricing: https://developers.openai.com/api/docs/pricing

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