Grok 4 vs Phi-3.5 Medium
A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.
Updated
Grok 4 specs · Phi-3.5 Medium specs- PriceGrok 4
Grok 4 publishes pricing ($15.00 / 1M output tokens) while Phi-3.5 Medium does not.
- Context windowGrok 4
Grok 4 accepts 256K tokens vs 128K, 2.0× the room for long documents and codebases.
- BenchmarksTie
No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores.
- ModalitiesGrok 4
Grok 4 supports 2 modalities (text, vision) vs 1 for Phi-3.5 Medium.
- OpennessPhi-3.5 Medium
Phi-3.5 Medium ships open weights (MIT); Grok 4 is API-only.
On balance Grok 4 edges ahead, winning 3 of 5 categories against Phi-3.5 Medium's 1. Grok 4 publishes pricing ($15.00 / 1M output tokens) while Phi-3.5 Medium does not. Grok 4 accepts 256K tokens vs 128K, 2.0× the room for long documents and codebases.
No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores. They differ in modality coverage, Grok 4 handles text, vision while Phi-3.5 Medium handles text, which can be the deciding factor before you even look at benchmarks. Phi-3.5 Medium ships open weights (MIT); Grok 4 is API-only.
Grok 4 is the newer of the two, released 11 months after Phi-3.5 Medium, which usually means a more recent knowledge cutoff and updated safety post-training. Grok 4 is usually picked for reasoning and research agent workloads, while Phi-3.5 Medium sees more deployments in on device and edge deployment. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.
Side-by-side specs
| Spec | Grok 4 | Phi-3.5 Medium |
|---|---|---|
| Provider | xAI | Microsoft |
| Released | Jul 2025 | Aug 2024 |
| Modalities | text, vision | text |
| Context window | 256K tokens | 128K tokens |
| Max output | , | , |
| Input · 1M | $3.00 / 1M tokens | Pricing not published |
| Output · 1M | $15.00 / 1M tokens | Pricing not published |
| Knowledge cutoff | 2024-11 | , |
| Open weights | No | Yes (MIT) |
| API available | Yes | Yes |
Pricing at scale
What you'd actually pay at typical workloads. Numbers come from each model's published per-million-token rates.
- Light usage, 100k in / 50k out per day$31.50 vs ,
- Heavy usage, 1M in / 500k out per day$315 vs ,
- RAG workload, 5M in / 200k out per day$540 vs ,
Light usage, 100k in / 50k out per day: pricing not directly comparable (one or both models are missing public per-token rates). Heavy usage, 1M in / 500k out per day: pricing not directly comparable (one or both models are missing public per-token rates). RAG workload, 5M in / 200k out per day: pricing not directly comparable (one or both models are missing public per-token rates).
Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.
- Grok 4$1.05
- Phi-3.5 MediumPricing unavailable
Benchmarks compared
Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.
- MMLU,78.9
- GPQA87.5
Grok 4 fits when…
- Real-time X data access
- Strong on benchmarks at launch
- Less restrictive content policy than peers
- Long-context tasks, handles 256K tokens vs 128K for Phi-3.5 Medium.
- Multimodal needs covering vision.
Phi-3.5 Medium fits when…
- MIT license
- 128k context
- Strong reasoning at 14B
- Self-hosting and on-prem requirements, open weights (MIT).
Consider Grok 3
xAI's first frontier-tier release, established the company's Colossus-trained model line.
Frequently asked
Is Grok 4 or Phi-3.5 Medium cheaper?
Per-token pricing isn't published for at least one of these models, check each model's spec page for current rates.Which has the larger context window?
Grok 4 accepts 256K tokens vs 128K for Phi-3.5 Medium.Is Grok 4 or Phi-3.5 Medium better for coding?
Both Grok 4 and Phi-3.5 Medium are competitive on coding benchmarks. See each model's individual spec page for HumanEval and SWE-bench scores where published. For an opinionated pick, consult our Best LLM for Coding ranking.Are either of these models open source?
Phi-3.5 Medium ships open weights (MIT). Grok 4 is API-only.When were Grok 4 and Phi-3.5 Medium released?
Grok 4 was released by xAI on 2025-07-09. Phi-3.5 Medium was released by Microsoft on 2024-08-20.
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