GPT-5 Codex vs Grok 4.3
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose GPT-5 Codex if you need
- ✓Choose Grok 4.3 if you need a 1M-token context for document-level multimodal tasks.
- ✓Choose Grok 4.3 if you need lower cost at $2.5 per million tokens.
- ✓Choose Grok 4.3 if you need integrated real-time tool access alongside complex reasoning.
- ✓Choose Grok 4.3 if you need helpful, direct responses without coherence loss in long outputs.
Choose Grok 4.3 if you need
- ✓Choose GPT-5 Codex if you need the highest intelligence index (44.6) for complex tasks.
- ✓Choose GPT-5 Codex if you need faster output at 149.9 tokens per second.
- ✓Choose GPT-5 Codex if you need strong coding specialization with unified text and image reasoning.
- ✓Choose GPT-5 Codex if you need effective handling of large inputs under 400k tokens.
Verdict
GPT-5 Codex leads slightly on raw intelligence (44.6 vs 43.9) and output speed while offering unified text-image reasoning and coding strength. Grok 4.3 counters with a 2.5× larger context window at one-quarter the price and real-time tool access for document-scale tasks. The choice hinges on whether users prioritize peak metrics or cost-effective long-context multimodal work.
GPT-5 Codex vs Grok 4.3: side by side
| Spec | GPT-5 Codex | Grok 4.3 | Winner |
|---|---|---|---|
| Intelligence | 44.6 | 43.9 | GPT-5 Codex |
| Output speed | 150 t/s | 135 t/s | GPT-5 Codex |
| Output price | $10.00/1M | $2.50/1M | Grok 4.3 |
| Context | 400K | 1000K | Grok 4.3 |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | OpenAI | xAI | Tie |
Detailed analysis
Intelligence
Winner: GPT-5 CodexGPT-5 Codex scores 44.6 on the intelligence index compared with Grok 4.3's 43.9. This edge aligns with its listed strengths in unified text-image reasoning and coding specialization. Grok 4.3 remains competitive on multi-step reasoning but trails by a small margin.
Speed
Winner: GPT-5 CodexGPT-5 Codex delivers 149.9 tokens per second versus Grok 4.3's 134.99. The speed advantage supports its capability for large-scale tasks. Both models are proprietary and fast enough for most multimodal use cases.
Pricing & Context
Winner: Grok 4.3Grok 4.3 costs $2.5 per million tokens with a 1M-token context while GPT-5 Codex costs $10 with a 400k-token limit. The larger window directly benefits document-level tasks listed in Grok 4.3's strengths. GPT-5 Codex notes higher resource demands at maximum context.
Multimodal Capabilities
Winner: TieBoth models handle text and image tasks as proprietary multimodal systems. GPT-5 Codex emphasizes unified reasoning while Grok 4.3 notes vision capabilities that are less mature than specialized models. Neither provides parameter counts or open weights.
GPT-5 Codex
Pros
- +Handles extremely large inputs effectively
- +Strong coding specialization
- +Unified text and image reasoning
Cons
- –High resource demands with maximum context
- –Limited to text and static images
- –Potential coherence loss in very long outputs
Grok 4.3
Pros
- +Strong performance on complex multi-step reasoning
- +Large context window for document-level tasks
- +Helpful and direct response style
- +Integrated real-time tool access
Cons
- –Vision capabilities less mature than specialized models
- –Occasional over-refusal on edge-case queries
- –High computational cost for maximum context usage
Summary: GPT-5 Codex vs Grok 4.3
Select GPT-5 Codex when maximum intelligence, speed, and coding performance matter most. Choose Grok 4.3 when large context, lower price, and tool access are priorities. The models split advantages clearly across cost, scale, and peak metrics.
Frequently asked questions
GPT-5 Codex leads on intelligence and speed; Grok 4.3 leads on context size and price. Neither dominates every dimension.