# GPT-5.4 pricing, and what it really costs per month

> GPT-5.4 pricing is $2.50 per million input and $15.00 output, verified 2026-07-02. Output bills 6x input, with worked monthly math.

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

## Answer
GPT-5.4 pricing is $2.50 per million input tokens and $15.00 per million output tokens, on rates verified 2026-07-02. Output bills six times input, so answer length drives your bill harder than prompt length. Culpa, a local-first LLM cost, margin, and forecast ledger, prices every call from that rate and names the conversation that spent it.

## Why this happens
GPT-5.4 is the production default for most teams, which makes it the least re-examined line on the bill. Its price shape matters more than its headline rate. The six-to-one output spread means a verbose response format costs more than a long system prompt, and the cached rate at $0.25 per million is a 90% discount most teams never claim because the repeated block isn't at the front of the prompt.

## What this usually looks like
- Your bill climbs while call count holds, which points at response length rather than traffic.
- Cached tokens sit near zero even though an identical system prompt goes out on every call.
- Nobody has re-tested whether GPT-5.4 mini would handle the routing and classification work at a third of the rate.
- One feature with open-ended responses outspends several features with far higher call volume.

## Common mistakes
- Comparing GPT-5.4 to another model on the input rate alone. Why it hurts: Output bills six times input here, so the headline input price hides most of your real cost. Do instead: Compare on your own token mix. Multiply both rates by the input and output volume you actually send.
- Leaving the response format open-ended. Why it hurts: On a six-to-one spread an extra hundred output tokens costs what six hundred input tokens would. Do instead: Cap max tokens and ask for the shortest form that works, then measure whether quality actually moved.
- Treating GPT-5.4 as the default for every step. Why it hurts: Classification and routing rarely need it, and mini runs at $0.75 input against $2.50 here. Do instead: Route the mechanical steps to mini and keep GPT-5.4 for the work that needs the quality.

## Self-check
- Pull input and output token totals separately for the last 30 days. Combined totals hide the six-to-one spread.
- Multiply each by the rates above. A large gap against your invoice means calls you aren't counting.
- Check what share of input billed at the cached $0.25 rate. Near zero is a 90% discount left untouched.
- Price your single longest completion this month. On a six-to-one spread it's rarely a rounding error.
- List which features use GPT-5.4 for work a mini model could do, and price the difference.

## A month on GPT-5.4, with the math shown (illustrative)
One feature sending 1 million input tokens and 200,000 output tokens in a month. Round numbers, so you can scale them to your own volume.
  1,000,000 input x $2.50 per million = $2.50
  200,000 output x $15.00 per million = $3.00
  Month total = $2.50 + $3.00 = $5.50, of which output is 55% on a fifth of the tokens
  If 60% of input hits the cached $0.25 rate: 600,000 x $0.25/M = $0.15, replacing $1.50
  Cached month total = $4.15, a 25% cut for one change to prompt ordering
Output is 55% of the bill on a fifth of the tokens. Caching the repeated input takes 25% off the total, and neither number is visible from a rate card alone.

## Cost figures
Every figure carries its confidence and its source. No figure on this site is provider-reported.
- $2.50 / $15.00 per million — GPT-5.4 input and output rates [calculated] Source: Culpa price book row for openai/gpt-5.4, $0.0025 and $0.015 per 1k, effective 2026-07-02, verified against OpenAI API pricing. Shown here per million.
- 6x — output rate as a multiple of the input rate on GPT-5.4 [calculated] Source: $15.00 divided by $2.50, from the same price-book row.
- 90% — discount the cached input rate carries against standard input [calculated] Source: 1 - ($0.25 / $2.50), using the cached and input rates from the same row.

## FAQ
Q: How much does GPT-5.4 cost per million tokens?
A: $2.50 for input and $15.00 for output, on rates verified 2026-07-02 against OpenAI's pricing page. Cached input runs at $0.25 per million, a 90% discount that only applies if the repeated block sits at the front of your prompt.

Q: Why is my GPT-5.4 bill higher than this calculation?
A: A published rate is a rate, not an invoice. Retries, tool definitions and conversation history resent on every turn all add tokens the arithmetic above doesn't include. The gap between the two is your effective cost.

Q: Is GPT-5.4 mini worth switching to?
A: For classification, routing and extraction, usually. Mini runs at $0.75 input and $4.50 output against $2.50 and $15.00 here, so the saving is roughly threefold on the same token volume. Test quality on your own data before moving reasoning work.

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

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