Comparison · Google and xAI
Gemini 3.8 Flash vs Grok 4.5
Listed API prices of Gemini 3.8 Flash 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), Gemini 3.8 Flash costs $0.131 and Grok 4.5 $0.336 at the prices listed in the United States on , so Gemini 3.8 Flash is 61.2 % less than Grok 4.5, counting visible output only, without cache discounts or hidden reasoning.
| Task | Gemini 3.8 Flash, per task | Grok 4.5, per task | Gemini 3.8 Flash, per month | Grok 4.5, per month | Gemini 3.8 Flash vs Grok 4.5, per task |
|---|---|---|---|---|---|
| L1Micro-task (classification or strict JSON extraction) | $0.0019per L1 task | $0.0042per L1 task | $27.38per month | $61.32per month | −55.4 % |
| L2Deep analysis over a 50,000-token document | $0.131per L2 task | $0.336per L2 task | $1,905.30per month | $4,905.60per month | −61.2 % |
| L3Agentic coding loop, 15 steps | $1.02per L3 task | $2.69per L3 task | $14,897.47per month | $39,201.00per month | −62.0 % |
Calculated Per month: 20 tasks an hour around the clock, 730 hours.
Prices USD per 1M tokens
| Price | Gemini 3.8 Flash | Grok 4.5 |
|---|---|---|
| Input, per 1M tokens | $0.750 | $2.00 |
| Output, per 1M tokens | $3.75 | $6.00 |
| Price from | Provider's price list · source page Published | OpenRouter · source page (data) Published |
| Read | · the United States | · the United States |
| Context window | 1,048,576 tokens | 500,000 tokens |
What can I use it for? six common tasks, our data checks
Quality on your task: not measured by Measured Lab yet.
| Task | Gemini 3.8 Flash | Grok 4.5 |
|---|---|---|
| Answer customer messages | Fits on price and context | — |
| Pull data from invoices and documents with strict JSON and page images | Fits on price and context | — |
| Summarize documents and meetings | Fits on price and context | — |
| Translate content | Fits on price and context | — |
| Chat assistant on your website | Fits on price and context | — |
| Write and review code with tool calls | Fits on price and context | — |
| Tasks it fits | 6 of 6 | — |
Checks of our data for six common tasks: a published price, a context window and answer length for the task and, where the task needs them, strict JSON output, page images and tool calls; prices, cost a month and terms for each model on its model card. Grok 4.5 is not in the model picker. Compare models for your own task in the model picker.
What breaks when you switch Published provider documentation
Moving from Google to xAI, 1 of the 5 features may not carry over, by each provider’s documentation:
- Streamed tool arguments — Google: yes; xAI: no. An interface that shows arguments as they are written sees nothing until the whole call is ready.
Moving from xAI to Google: every feature that xAI’s documentation lists as supported is also listed as supported by Google.
| Feature of the API | 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 | Not stated | 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.