AI model comparison
Compare recorded price, context, output limits, speed, latency, capabilities, and input/output support. Every missing value stays visible, and unsourced benchmarks are excluded.
This Gpt 5 Nano:Flex vs Grok 4 1 Fast Reasoning comparison is designed for teams choosing between two production model records, not for declaring a universal winner. Gpt 5 Nano:Flex by Openai via Requesty currently records 400K context, 128K maximum output, $0.03 input per 1M tokens, $0.20 output per 1M tokens. Grok 4 1 Fast Reasoning by Xai via Requesty records 2M context, 30K maximum output, $0.20 input per 1M tokens, $0.50 output per 1M tokens. The tables below separate documented capabilities, commercial limits, directory measurements, and source-linked benchmark evidence so you can see where the data is complete and where independent testing is still required.
Openai via Requesty
GPT-5 nano is OpenAI's fastest, cheapest version of GPT-5. It's great for summarization and classification tasks.
Accepts
Produces
Xai via Requesty
A frontier multimodal model optimized specifically for high-performance agentic tool calling.
Accepts
Produces
At a glance
This is a directional summary of the values recorded in this directory—not a universal quality verdict. Test the finalists on your own prompts before committing.
Where Gpt 5 Nano:Flex leads in recorded data
Where Grok 4 1 Fast Reasoning leads in recorded data
Context capacity
Higher listed limit
Gpt 5 Nano:Flex:400K
Grok 4 1 Fast Reasoning:2M
Grok 4 1 Fast Reasoning
Maximum output
Higher listed limit
Gpt 5 Nano:Flex:128K
Grok 4 1 Fast Reasoning:30K
Gpt 5 Nano:Flex
Input price
Lower recorded price
Gpt 5 Nano:Flex:$0.03
Grok 4 1 Fast Reasoning:$0.20
Gpt 5 Nano:Flex
Output price
Lower recorded price
Gpt 5 Nano:Flex:$0.20
Grok 4 1 Fast Reasoning:$0.50
Gpt 5 Nano:Flex
Output speed
Higher recorded throughput
Gpt 5 Nano:Flex:—
Grok 4 1 Fast Reasoning:—
No complete comparison
Time to first token
Lower recorded latency
Gpt 5 Nano:Flex:—
Grok 4 1 Fast Reasoning:—
No complete comparison
Intelligence Index
Higher directory index
Gpt 5 Nano:Flex:—
Grok 4 1 Fast Reasoning:—
No complete comparison
Evidence
A score appears only when both records include a verified source. It is not treated as a universal ranking.
Specifications
| Specification | Gpt 5 Nano:Flex | Grok 4 1 Fast Reasoning |
|---|---|---|
| Provider | Openai via Requesty | Xai via Requesty |
| Model family | — | — |
| Accepted inputs | text, image | text, image |
| Produced outputs | text | text |
| Context window | 400K | 2MRecorded lead |
| Max output | 128KRecorded lead | 30K |
| Intelligence Index | — | — |
| Input price / 1M | $0.03Recorded lead | $0.20 |
| Output price / 1M | $0.20Recorded lead | $0.50 |
| Output speed | — | — |
| Time to first token | — | — |
| Reasoning mode | Documented | Documented |
| Tool calling | Documented | Documented |
| Image input | Documented | Documented |
| Audio input | Not documented | Not documented |
| Structured output | Documented | Documented |
| License | Not documented | Not documented |
| Released | Not documented | Nov 19, 2025 |
Workload guidance
Gpt 5 Nano:Flex currently leads on larger maximum output, lower recorded input price, lower recorded output price. Grok 4 1 Fast Reasoning currently leads on larger context. Choose according to the constraints that matter to your workload, then run the same representative prompts against both models before making a production commitment. Neither the larger number nor the lower price is automatically the better choice: prompt quality, tool reliability, modality support, rate limits, data policy, and provider implementation can change the result. Use this page to build a shortlist, confirm current terms in the linked sources, and validate quality, latency, and cost with your own traffic.
Provenance
Prices and hosted performance can change. SyncDev records source references and clearly separates documented specifications from measured values; confirm commercial terms with the provider before deployment.
Gpt 5 Nano:Flex
Openai via Requesty · model record and recorded source
Grok 4 1 Fast Reasoning
Xai via Requesty · model record and recorded source
Choose any two approved model records and review them with the same evidence rules.