High-volume, cost-sensitive work
Choose Grok 4.20 Reasoning
Grok 4.20 Reasoning costs 7% less on a typical mix of three input tokens for every output token ($1.56 against $1.69 per million tokens).
GPT-5.4 Mini vs Grok 4.20 Reasoning: price, context and capabilities
Choose GPT-5.4 Mini for reused prompts and documents (RAG, agents). Choose Grok 4.20 Reasoning for high-volume, cost-sensitive work, writing and code generation and very long inputs.
In short
- Grok 4.20 Reasoning is 7% cheaper than GPT-5.4 Mini at the headline price ($1.56 / 1M tokens vs $1.69 / 1M tokens).
- Grok 4.20 Reasoning reads more per request: 1M tokens against 400k.
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Grok 4.20 Reasoning
Grok 4.20 Reasoning charges $2.50 per million output tokens, against $4.50 for GPT-5.4 Mini. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose GPT-5.4 Mini
GPT-5.4 Mini charges $0.08 per million cached input tokens, against $0.20 for Grok 4.20 Reasoning.
Very long inputs
Choose Grok 4.20 Reasoning
Grok 4.20 Reasoning reads up to 1M tokens per request, against 400k for GPT-5.4 Mini.
Monthly cost at three volumes
| Volume | GPT-5.4 Mini | Grok 4.20 Reasoning | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $1.88 | $1.88 | = |
| Production: 20M input, 5M output tokens | $37.50 | $37.50 | = |
| Scale: 500M input, 100M output tokens | $825.00 | $875.00 | GPT-5.4 Mini, $50.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| GPT-5.4 Mini | Grok 4.20 Reasoning | |
|---|---|---|
| Provider | OpenAI | xAI |
| Category | Language models | Language models |
| Status | Legacy | Generally available |
| Headline price | $1.69 / 1M tokens | $1.56 / 1M tokens |
| Input | $0.75 / 1M tokens | $1.25 / 1M tokens |
| Output | $4.50 / 1M tokens | $2.50 / 1M tokens |
| Cached input | $0.075 / 1M tokens | $0.20 / 1M tokens |
| Context window | 400k | 1M |
| Max output | 128k | No data |
| Released | Mar 17, 2026 | March 2026 |
| Knowledge cutoff | August 2025 | No data |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | gpt-5.4-mini | grok-4.20-0309-reasoning |
Benchmarks side by side
Leader in bold.
| Benchmark | GPT-5.4 Mini | Grok 4.20 Reasoning |
|---|---|---|
| Intelligence Index | 24.1 | No data |
| Terminal-Bench Hard | 52.3% | No data |
| SciCode | 52.1% | No data |
| GPQA Diamond | 87.5% | No data |
| Humanity's Last Exam | 28.1% | No data |
| IFBench (instruction following) | 73.3% | No data |
| τ²-Bench (agentic tool use) | 83.3% | No data |
| MMMU-Pro (visual reasoning) | 73.3% | No data |
| Long-context reasoning (AA-LCR) | 77% | No data |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose GPT-5.4 Mini or Grok 4.20 Reasoning?
Choose GPT-5.4 Mini for reused prompts and documents (RAG, agents). Choose Grok 4.20 Reasoning for high-volume, cost-sensitive work, writing and code generation and very long inputs.
Which is cheaper, GPT-5.4 Mini or Grok 4.20 Reasoning?
Grok 4.20 Reasoning is 7% cheaper than GPT-5.4 Mini at the headline price ($1.56 / 1M tokens vs $1.69 / 1M tokens).
Which has the larger context window, GPT-5.4 Mini or Grok 4.20 Reasoning?
Grok 4.20 Reasoning reads more per request: 1M tokens against 400k.
What is the difference between GPT-5.4 Mini and Grok 4.20 Reasoning?
GPT-5.4 Mini is made by OpenAI and Grok 4.20 Reasoning by xAI. Grok 4.20 Reasoning is 7% cheaper than GPT-5.4 Mini at the headline price ($1.56 / 1M tokens vs $1.69 / 1M tokens). Grok 4.20 Reasoning reads more per request: 1M tokens against 400k.
How much do GPT-5.4 Mini and Grok 4.20 Reasoning cost per month?
At 20 million input and 5 million output tokens a month, GPT-5.4 Mini costs $37.50 and Grok 4.20 Reasoning costs $37.50, at standard rates.