Comparison · OpenAI and xAI
GPT-5.4 vs Grok 4.5
Listed API prices of GPT-5.4 and Grok 4.5 turned into the cost of the same three standard tasks and what each provider’s API documentation says about features that break on a switch. Output quality, speed and answer length are not compared.
Calculated impact cost per task and per month
For an L2 task (deep analysis over a 50,000-token document, 3 steps), GPT-5.4 costs $0.443 and Grok 4.5 $0.336 at the prices listed in the United States on , so GPT-5.4 is 31.7 % more than Grok 4.5, counting visible output only, without cache discounts or hidden reasoning.
| Task | GPT-5.4, per task | Grok 4.5, per task | GPT-5.4, per month | Grok 4.5, per month | GPT-5.4 vs Grok 4.5, per task |
|---|---|---|---|---|---|
| L1Micro-task (classification or strict JSON extraction) | $0.0067per L1 task | $0.0042per L1 task | $98.55per month | $61.32per month | +60.7 % |
| L2Deep analysis over a 50,000-token document | $0.443per L2 task | $0.336per L2 task | $6,460.50per month | $4,905.60per month | +31.7 % |
| L3Agentic coding loop, 15 steps | $3.42per L3 task | $2.69per L3 task | $49,986.75per month | $39,201.00per month | +27.5 % |
Calculated Per month: 20 tasks an hour around the clock, 730 hours.
Prices USD per 1M tokens
| Price | GPT-5.4 | Grok 4.5 |
|---|---|---|
| Input, per 1M tokens | $2.50 | $2.00 |
| Output, per 1M tokens | $15.00 | $6.00 |
| Price from | OpenRouter · source page (data) Published | OpenRouter · source page (data) Published |
| Read | · the United States | · the United States |
| Context window | 1,050,000 tokens | 500,000 tokens |
What breaks when you switch Published provider documentation
Moving from OpenAI to xAI, 2 of the 5 features may not carry over, by each provider’s documentation:
- Streamed tool arguments — OpenAI: yes; xAI: no. An interface that shows arguments as they are written sees nothing until the whole call is ready.
- Cache covers tool definitions — OpenAI: yes; xAI: not stated. Where the cache does not cover tool definitions, a long tool list is paid as fresh input on every request.
Moving from xAI to OpenAI: every feature that xAI’s documentation lists as supported is also listed as supported by OpenAI.
| Feature of the API | OpenAI | xAI |
|---|---|---|
| Strict JSON schemas | Yes | Yes |
| Parallel tool calls | Yes | Yes |
| Streamed tool arguments | Yes | No |
| Reasoning with tools | Yes | Yes |
| Cache covers tool definitions | Yes | Not stated |
What each provider’s own API documentation says, read ; “not stated” is not the same as “no”. Quotes and sources: what breaks when you switch AI APIs.